(4) Repeat the steps in paragraphs (c)(2) and (3) of this section for additional acceleration and deceleration rates in 1 mph/s increments up to and including one increment above the maximum acceleration rate expected during testing.  Average the five repeat runs to calculate a mean acceleration rate, , at each setting.
(5) Compare each mean acceleration rate, , to the corresponding nominal acceleration rate, aref, to determine values for acceleration error, aerror, using the following equation:

      Eq. 1066.265-3

Example:
 = 0.999 mph/s
aref = 1 mph/s

aerror =  - 0.100 %

(d) Verification of forces for controlling acceleration and deceleration.  Program the dynamometer with a calculated force value and determine actual acceleration and deceleration rates as the dynamometer traverses speeds between 10 and 40 mph at various nominal acceleration and deceleration rates. Verify the dynamometer's ability to achieve certain acceleration and deceleration rates with a given force as follows:
(1) Calculate the force setting, F, using the following equation:

      Eq. 1066.265-4
Where:
Ib = the dynamometer manufacturer's stated base inertia, in lbf·s[2]/ft.
a = nominal acceleration rate, in ft/s[2].

Example:
Ib = 2967 lbm = 92.217 lbf· s[2]/ft
a = 1 mph/s = 1.4667 ft/s[2]

F = 135.25 lbf

(2) Set the dynamometer to road-load mode and program it with a calculated force to accelerate the roll at a nominal rate of 1 mph/s from 10 mph to 40 mph.  Measure the elapsed time to reach the target speed, to the nearest 0.01 s.  Repeat this measurement for a total of five runs.  Determine the actual acceleration rate, aact, for each run using Eq. 1066.265-2.  Repeat this step to determine measured "negative acceleration" rates using a calculated force to decelerate the roll at a nominal rate of 1 mph/s from 40 mph to 10 mph.  Average the five repeat runs to calculate a mean acceleration rate, , at each setting.
(3) Repeat the steps in paragraph (d)(2) of this section for additional acceleration and deceleration rates as specified in paragraph (c)(4) of this section.
(4) Compare each mean acceleration rate, , to the corresponding nominal acceleration rate, aref, to determine values for acceleration error, aerror, using Eq. 1066.265-3
(e) Performance evaluation. The acceleration error from paragraphs (c)(5) and (d)(4) of this section may not exceed +-1.0 %.

§1066.270 Unloaded coastdown verification.
(a) Overview.  Use force measurements to verify the dynamometer's settings based on coastdown procedures.
(b) Scope and frequency.  Perform this verification upon initial installation, within 7 days of testing, and after major maintenance.
(c) Procedure.  This procedure verifies the dynamometer's settings derived from coastdown testing.  For dynamometers that have an automated process for this procedure, perform this evaluation by setting the initial speed, final speed, inertial coefficients, and road-load coefficients as required for each test, using good engineering judgment to ensure that these values properly represent in-use operation.  Use the following procedure if your dynamometer does not perform this verification with an automated process:
(1) Warm up the dynamometer as specified by the dynamometer manufacturer.
(2) With the dynamometer in coastdown mode, set the dynamometer inertia for the smallest vehicle weight that you expect to test and set A, B, and C road-load coefficients to values typical of those used during testing.  Program the dynamometer to coast down over the dynamometer operational speed range (typically from a speed of 80 mph through a minimum speed at or below 10 mph).  Perform at least one coastdown over this speed range, collecting data over each 10 mph interval.
(3) Repeat the steps in paragraph (c)(2) of this section with the dynamometer inertia and road-load coefficients set for the largest vehicle weight that you expect to test.
(4) Determine the average coastdown force, F, for each speed and inertia setting for each of the coastdowns performed using the following equation:

      Eq. 1066.270-1
Where:
F = the average force measured during the coastdown for each speed interval and inertia setting, expressed in lbf· s[2]/ft and rounded to four significant figures.
I = the dynamometer's inertia setting, in lbf· s[2]/ft.
vinit = the speed at the start of the coastdown, expressed in ft/s and rounded to four significant figures.
vfinal = the speed at the end of the coastdown interval, rounded to four significant figures.
t = coastdown time for each speed and inertia setting, accurate to at least 0.01 s.

Example:
I = 2000 lbm = 65.17 lbf · s[2]/ft
vinit = 25 mph = 36.66 ft/s
vfinal = 15 mph = 22.0 ft/s
t = 5.00 s

F = 191.1 lbf

(5) Calculate the target value of coastdown force, Fref, based on the applicable dynamometer parameters for each speed and inertia setting.
(6) Compare the mean value of the coastdown force measured for each speed and inertia setting, , to the corresponding Fref to determine values for coastdown force error, Ferror, using the following equation:

      Eq. 1066.270-2

Example:
Fref = 192 lbf
 = 191 lbf

Ferror = 0.5 %

(d) Performance evaluation. The coastdown force error determined in paragraph (c) of this section may not exceed the following:
(i) For vehicles at or below 20,000 pounds GVWR, calculate Ferrormax from the following formula:
Ferrormax (%) = (2.2 lbf/Fref)·100
      Eq. 1066.270-3

Example:
Fref = 192 lbf
Ferrormax (%) = (2.2/192)·100 = 1.14%
(ii) For vehicles above 20,000 pounds GVWR, the maximum allowable error, Ferrormax, for all speed and inertia settings is +-1.0 % or +-39.2 N, whichever is greater.
(e) If the dynamometer is not able to meet this requirement, diagnose and repair the dynamometer before continuing with emission testing.  Diagnosis should include performing the verifications in §1066.255 and §1066.260.

§1066.280 Daily dynamometer readiness verification.
(a) Overview.  This section describes how to verify that the dynamometer is ready for emission testing.
(b) Scope and frequency.  Perform this verification upon initial installation, within 1 day before testing, and after major maintenance.
(c) Procedure.  For dynamometers that have an automated process for this verification procedure, perform this evaluation by setting the initial speed and final speed and the inertial and road-load coefficients as required for the test, using good engineering judgment to ensure that these values properly represent in-use operation.  Use the following procedure if your dynamometer does not perform this verification with an automated process:
(1) With the dynamometer in coastdown mode, set the dynamometer inertia to the base inertia with the road-load coefficient A set to 20 lbf (or a force that results in a coastdown time of less than 10 minutes) and coefficients B and C set to 0.  Program the dynamometer to coast down for one 10 mph interval from 55 mph down to 45 mph.  If your dynamometer is not capable of performing one discrete coastdown, then coast down with preset 10 mph intervals that include a 55 mph to 45 mph interval.
(2) Perform the coastdown.
(3) Determine the coastdown force and coastdown force error using Eqs. 1066.270-1 and 1066.270-2.
(d) Performance evaluation. The coastdown force error determined in paragraph (c) of this section may not exceed the following:
(1)  For vehicles at or below 20,000 pounds GVWR, +-1.0 % or +-9.8 N (+-2.2 lbf), whichever is greater.
(2) For vehicles above 20,000 pounds GVWR, +-1.0 % or +-39.2 N (+-8.8 lbf), whichever is greater.
(e) If the verification results fail to meet the performance criteria in paragraph (d) of this section, perform the procedure up to two additional times.  If the dynamometer is consistently unable to meet the performance criteria, diagnose and repair the dynamometer before continuing with emission testing.  Diagnosis should include performing the verifications in §1066.255 and §1066.260.

§1066.290 Driver's aid.
Use good engineering judgment to provide a driver's aid that facilitates compliance with the requirements of §1066.430.  Verify the speed accuracy of the driver's aid as described in §1066.235.

Subpart D -- Coastdown
§1066.301 Overview of coastdown procedures.
(a) The coastdown procedures described in this subpart are used to determine the load coefficients (A, B, and C) for the simulated road-load equation in §1066.210(d)(3).
(b) The general procedure for performing coastdown tests and calculating load coefficients is described in SAE J1263 and SAE J2263 (incorporated by reference in §1066.1010).  This subpart specifies certain deviations from those procedures for certain applications.
(c) Use good engineering judgment for all aspects of coastdown testing.  For example, minimize the effects of grade by performing coastdown testing on reasonably level surfaces and determining coefficients based on average values from vehicle operation in opposite directions over the course.

§1066.305 Coastdown procedures for motor vehicles at or below 14,000 pounds GVWR.
For motor vehicles at or below 14,000 pounds GVWR, develop representative road-load coefficients to characterize each test vehicle.  Calculate road-load coefficients by performing coastdowns using the provisions of SAE J1263 and SAE J2263 (incorporated by reference in §1066.1010).  Perform coastdowns at a starting speed as specified in SAE J2263, or at the highest speed from the range of applicable duty cycles.  Use the same road-load coefficients for all duty cycles.  However, if your test conditions are substantially different from the conditions represented by your road-load coefficients, such as cold-temperature testing, you may use good engineering judgment to develop separate road-load coefficients.

§1066.310 Coastdown procedures for vehicles above 14,000 pounds GVWR.
This section describes coastdown procedures that are unique to vehicles above 14,000 pounds GVWR.  These procedures are valid for calculating road-load coefficients for chassis and post-transmission powerpack testing and for calculating drag area (CDA) for use in the GEM simulation tool under 40 CFR part 1037.
(a) Determine load coefficients by performing a minimum of 16 valid coastdown runs (8 in each direction).
(b) Follow the provisions of Sections 1 through 9 of SAE J1263, and SAE J2263 (incorporated by reference in §1066.1010), except as described in this paragraph (b).  The terms and variables identified in this paragraph (b) have the meaning given in SAE J1263 or J2263 unless specified otherwise.
(1) The test condition specifications of SAE J1263 apply except as follows for wind and road conditions:
(i) We recommend that you do not perform coastdown testing on days for which winds are forecast to exceed 6.0 mph.
(ii) The grade of the test track or road must not be excessive (considering factors such as road safety standards and effects on the coastdown results).  Road conditions should follow Section 7.4 of SAE J1263, except that road grade may exceed 0.5%.  If road grade is greater than 0.02% over the length of the test surface, then the road grade as a function of distance along the length of the test surface must be incorporated into the analysis.  To calculate the force due to grade use Section 11.5 of SAE J2263.
(2) Operate the vehicle at a top speed above 70 mph, or at its maximum achievable speed if it cannot reach 70 mph.  If a vehicle is equipped with a vehicle speed limiter that is set for a maximum speed below 70 mph, you must disable the vehicle speed limiter.  Start the test at or above 70 mph or at the vehicle's maximum achievable speed if it cannot reach 70 mph.  Collect data through a minimum speed at or below 15 mph.  Data analysis for valid coastdown runs must include a maximum speed as described in this paragraph (b)(2) and a minimum speed of 15 mph.
(3) Gather data regarding wind speed and direction, in coordination with time-of-day data, using at least one stationary electro-mechanical anemometer and suitable data loggers meeting the specifications of SAE J1263, as well as the following additional specifications for the anemometer placed adjacent to the test surface:
(i) Calibrate the equipment by running the zero-wind and zero-angle calibrations within 24 hours before conducting the coastdown procedures.  If the coastdown procedures are not complete 24 hours after calibrating the equipment, repeat the calibration for another 24 hours of data collection.
(ii) Record the location of the anemometer using a GPS measurement device adjacent to the test surface (approximately) at the midway distance along the test surface used for coastdowns.
(iii) Position the anemometer such that it will be at least 2.5 but not more than 3.0 vehicle widths from the test vehicle's centerline as the test vehicle passes the location of that anemometer.
(iv) Mount the anemometer at a height that is within 6 inches of half the test vehicle's maximum height.
(v) Place the anemometer at least 50 feet from the nearest tree and at least 25 feet from the nearest bush (or equivalent roadside features).
(vi) The height of the grass surrounding the stationary anemometer may not exceed 10% of the anemometer's mounted height, within a radius equal to the anemometer's mounted height.
(4) You may split runs as per Section 9.3.1 of SAE J2263, but we recommend whole runs.  If you split a run, analyze each portion separately, but count the split runs as one run with respect to the minimum number of runs required.
(5) You may perform consecutive runs in a single direction, followed by consecutive runs in the opposite direction, consistent with good engineering judgment.  Harmonize starting and stopping points to the extent practicable to allow runs to be paired.
(6) All valid coastdown run times in each direction must be within 2.0 standard deviations of the mean of the valid coastdown run times (from 70 mph down to 15 mph) in that direction.  Eliminate runs outside this range.  After eliminating these runs you must have at least eight valid runs in each direction.  You may use coastdown run times that do not meet these standard deviation requirements if we approve it in advance.  In your request, describe why the vehicle is not able to meet the specified standard deviation requirements and propose an alternative set of requirements.
(7) Analyze data for chassis and post-transmission powerpack testing or for use in the GEM simulation tool as follows:
(i) Follow the procedures specified in Section 10 of SAE J1263 or Section 11 of SAE J2263 to calculate coefficients for chassis and post-transmission powerpack testing.
(ii) Determine drag area, CDA, as follows instead of using the procedure specified in Section 10 of SAE J1263:
(A) Measure vehicle speed at fixed intervals over the coastdown run (generally at 10 Hz), including speeds at or above 15 mph and at or below 70 mph.  Establish the height or altitude corresponding to each interval as described in SAE J2263 if you need to incorporate the effects of road grade.
(B) Calculate the vehicle's effective mass, Me, in kg by adding 56.7 kg to the measured vehicle mass for each tire making road contact.  This accounts for the rotational inertia of the wheels and tires.
(C) Calculate the road-load force for each measurement interval, Fi, for values of i >= 1 using the following equation:

      Eq. 1066.310-1
Where:
Me = the vehicle's effective mass, expressed to at least the nearest 0.1 kg.
v = vehicle speed at the beginning and end of the measurement interval.
Δt = elapsed time over the measurement interval, in seconds.

(D) Plot the data from all the coastdown runs on a single plot of Fi vs. vi[2] to determine the slope correlation, D, based on the following equation:

      Eq. 1066.310-2
Where:
g = gravitational acceleration = 9.81 m/s[2].
Δh = change in height or altitude over the measurement interval, in m.  Assume Δh = 0 if you are not correcting for grade.
Δs = distance the vehicle travels down the road during the measurement interval, in m.
Am = the calculated value of the y-intercept based on the curve-fit.

(E) Calculate drag area, CDA, in m[2] using the following equation:

      Eq. 1066.310-3
Where:
ρ = air density at reference conditions = 1.17 kg/m[3].

      Eq. 1066.310-4
 = average ambient absolute temperature during testing, in K.
 = average ambient pressuring during the test, in kPa.

(8) Determine the A, B, and C coefficients identified in §1066.210 as follows:
(i) For chassis and post-transmission powerpack testing, follow the procedures specified in Section 10 of SAE J1263 or Section 12 of SAE J2263.
(ii) For the GEM simulation tool, use the following values:
A = Am
B = 0
C = Dadj

§1066.320 Dynamometer road-load setting.
Determine dynamometer road-load settings for chassis testing by following SAE J2264 (incorporated by reference in §1066.1010).

Subpart E --  Preparing Vehicles and Running an Exhaust Emission Test
§1066.401 Overview.
(a) Use the procedures detailed in this subpart to measure vehicle emissions over a specified drive schedule.  Different procedures may apply for criteria pollutants and greenhouse gas emissions as described in subpart I of this part or the standard-setting part.  This subpart describes how to:
(1) Determine road-load power, test weight, and inertia class.
(2) Prepare the vehicle, equipment, and measurement instruments for an emission test.
(3) Perform pre-test procedures to verify proper operation of certain equipment and analyzers and to prepare them for testing.
(4) Record pre-test data.
(5) Sample emissions.
(6) Record post-test data.
(7) Perform post-test procedures to verify proper operation of certain equipment and analyzers.
(8) Weigh PM samples.
(b) The overall test generally consists of prescribed sequences of fueling, parking, and driving at specified test conditions.  An exhaust emission test generally consists of measuring emissions and other parameters while a vehicle follows the drive schedules specified in the standard-setting part.  There are two general types of test cycles:
(1) Transient cycles.  Transient test cycles are typically specified in the standard-setting part as a second-by-second sequence of vehicle speed commands. Operate a vehicle over a transient cycle such that the speed follows the target values.  Proportionally sample emissions and other parameters and use the calculations in 40 CFR part 1065, subpart G, or subpart G of this part to calculate emissions.  The standard-setting part may specify three types of transient testing based on the approach to starting the measurement, as follows:
(i) A cold-start transient cycle where you start to measure emissions just before starting an engine that has not been warmed up.
(ii) A hot-start transient cycle where you start to measure emissions just before starting a warmed-up engine.
(iii) A hot running transient cycle where you start to measure emissions after an engine is started, warmed up, and running.
(2) Cruise cycles.  Cruise test cycles are typically specified in the standard-setting part as a discrete operating point that has a single speed command.
(i) Start a cruise cycle as a hot running test, where you start to measure emissions after the engine is started and warmed up and the vehicle is running at the target test speed.
(ii) Sample emissions and other parameters for the cruise cycle in the same manner as a transient cycle, with the exception that the reference speed value is constant.  Record instantaneous and mean speed values over the cycle.

§1066.407 Vehicle preparation and preconditioning.
Prepare the vehicle for testing (including measurement of evaporative and refueling emissions, as required) as described in the standard-setting part.

§1066.410 Dynamometer test procedure.
(a) Dynamometer testing may consist of multiple drive cycles with both cold-start and hot-start portions, including prescribed soak times before each test interval.  The standard-setting part identifies the driving schedules and the associated sample intervals, soak periods, engine startup and shutdown procedures, and operation of accessories, as applicable.  Not every test interval includes all these elements.
(b) Place the vehicle onto the dynamometer without starting the engine (for cold-start test cycles) or drive the vehicle onto dynamometer (for hot-start and hot-running cycles only) and position a fan that directs cooling air to the vehicle during dynamometer operation as described in this paragraph (b).  This generally requires squarely positioning the fan in front of the vehicle and directing the airflow to the vehicle's radiator.  Use good engineering judgment to design and configure fans to cool the test vehicle in a way that properly simulates in-use operation, consistent with the specifications of §1066.105.  Except for the following special cases, use a road-speed modulated fan meeting the requirements of §1066.105(c)(2) or (d) that is placed within 90 cm of the front of the vehicle and ensure that the engine compartment cover is closed:
(1) For SC03 and AC17 testing, use a road-speed modulated fan meeting the requirements of §1066.105(c)(3).  Position the discharge nozzle such that its lowest point is not more than 16 cm above the floor of the test cell.
(2) For FTP, LA-92, US06, or HFET testing of vehicles at or below 14,000 pounds GVWR, you may use a fixed-speed fan meeting the requirements of §1066.105(c)(4) or (c)(5) as specified in the following table, with the engine compartment cover open:
Table 1 of §1066.410 - Fixed-speed fan capacity and position specifications.
Test cycle
Maximum fan capacity
Approximate distance from the front of the vehicle
FTP
Up to 2.50 m[3]/s
0 to 30 cm
US06
2.50 m[3]/s to 7.10 m[3]/s
0 to 60 cm
LA-92
Up to 2.50 m[3]/s
0 to 30 cm
HFET
Up to 2.50 m[3]/s
0 to 30 cm

(c) Record the vehicle's speed trace based on the time and speed data from the dynamometer.  Record speed to at least the nearest 0.01 mph and time to at least the nearest 0.01 s.
(d) You may perform practice runs for operating the vehicle and the dynamometer controls to meet the driving tolerances specified in §1066.430 or adjust the emission sampling equipment.  Verify that the accelerator pedal allows for enough control to closely follow the prescribed driving schedule.  We recommend that you verify your ability to meet the minimum dilution factor requirements of §1066.110(b)(2)(iii)(B) during these practice runs.
(e) Inflate tires on drive wheels according to the vehicle manufacturer's specifications.  The tire pressure for drive wheels must be the same for dynamometer operation and for dynamometer coastdown procedures used for determining road-load coefficients.  Report these tire pressure values with the test results.
(f) Tie down or load the test vehicle as needed to provide a normal force at the tire and dynamometer roll interface to prevent wheel slip.  For vehicles above 14,000 pounds GVWR, report this force with the test results.
(g) For vehicles which provide four-wheel drive or all-wheel drive operation, utilize the vehicle's normal (default) mode of operation.  (For purposes of this paragraph (g), the term four-wheel drive includes other multiple drive axle configurations.)  This may involve testing four-wheel drive or all-wheel drive on a dynamometer with a separate dynamometer roll for each drive axle.  Alternatively, two drive axles may use a single roll, as described in §1066.210(d)(1). You may also test the vehicle on a single roll by deactivating the second set of drive wheels, but only if this mode of operation does not decrease emissions or energy consumption relative to normal in-use operation.  We may test such vehicles in four-wheel or all-wheel mode on one or more rolls to confirm that the alternate dynamometer procedures did not decrease emissions.
(h) Determine test weight as follows:
(1) For vehicles at or below 14,000 pounds GVWR, determine ETW as described in §1066.810.  Set dynamometer vehicle inertia, I, based on dynamometer type, as follows:
(i) For two-wheel drive dynamometers, set I = ETW.
(ii) For four-wheel drive dynamometers, set I = 0.985∙ETW.
(2) For vehicles above 14,000 pounds GVWR, determine the vehicle's effective mass as described in 1066.310.  This is the test weight.
(i) Warm up the dynamometer as recommended by the dynamometer manufacturer.
(j) Following the test, determine the actual driving distance by counting the number of dynamometer roll or shaft revolutions, or by integrating speed over the course of testing from a high-resolution encoder system.

§1066.420 Vehicle operation.
This section describes how to test a conventionally configured vehicle (vehicles with transmission shifters, foot pedal accelerators, etc).  You may ask us to modify these procedures for vehicles that do not have these control features.
(a) Start the vehicle as follows:
(1) At the beginning of the test cycle, start the vehicle according to the procedure described in the owners manual.  In the case of hybrid vehicles, this would generally involve activating vehicle systems such that the engine will start when the vehicle's control algorithms determine that the engine should provide power instead of or in addition to power from the rechargeable energy storage system (RESS).  Unless we specify otherwise, engine starting throughout this part generally refers to this step of activating the system on hybrid vehicles, whether or not that causes the engine to start running.
(2) Place the transmission in gear as described by the test cycle in the standard-setting part.  During idle operation, apply the brakes if necessary to keep the drive wheels from turning.
(b) If the vehicle does not start after your recommended maximum cranking time, wait and restart cranking according to your recommended practice.  If you do not recommend such a cranking procedure, stop cranking after 10 seconds, wait for 10 seconds, then start cranking again for up to 10 seconds.  You may repeat this for up to three start attempts.  If the vehicle does not start after three attempts, you must determine and record the reason for failure to start.  Shut off sampling systems and either turn the CVS off or disconnect the exhaust tube from the tailpipe during the diagnostic period to prevent flow through the exhaust system.  Reschedule the vehicle for testing.  This may require performing vehicle preparation and preconditioning if the testing needs to be rerun from a cold start.  If failure to start occurs during a hot-start test, you may reschedule the hot-start test without repeating the cold-start test, as long as you bring the vehicle to a hot-start condition before starting the hot-start test.
(c) Repeat the recommended starting procedure if the engine has a false start (i.e., an incomplete start).
(d) Take the following steps if the engine stalls:
(1) If the engine stalls during an idle period, restart the engine immediately and continue the test. If you cannot restart the engine soon enough to allow the vehicle to follow the next acceleration, stop the driving schedule indicator and reactivate it when the vehicle restarts.
(2) Void the test if the vehicle stalls during vehicle operation.  If this happens, remove the vehicle from the dynamometer, take corrective action, and reschedule the vehicle for testing.  Record the reason for the malfunction (if determined) and any corrective action.  See the standard-setting part for instructions about reporting these malfunctions.
(e) Operate vehicles during testing as follows:
(1) Where we do not give specific instructions, operate the vehicle according to the recommendations in the owners manual, unless those recommendations are unrepresentative of what may reasonably be expected for in-use operation.
(2) If vehicles have features that preclude dynamometer testing, you may modify these features as necessary to allow testing, consistent with good engineering judgment, as long as it does not affect your ability to show that your vehicles comply with standards.  Send us written notification describing these changes along with supporting rationale.
(3) Operate vehicles during idle as follows:
(i) For vehicles with automatic transmission, operate at idle with the transmission in "Drive" with the wheels braked, except that you may shift to "Neutral" for the first idle period and for any idle period longer than one minute.  If you put the vehicle in "Neutral" during an idle, you must shift the vehicle into "Drive" with the wheels braked at least 5 seconds before the end of the idle period.  Note that this does not preclude vehicle designs involving engine operation with stop-start functions where the engine stops when the brake is applied below a certain threshold speed and restarts upon release of the brake.
(ii) For vehicles with manual transmission, operate at idle with the transmission in gear with the clutch disengaged, except that you may shift to "Neutral" with the clutch engaged for the first idle period and for any idle period longer than one minute.  If you put the vehicle in "Neutral" during idle, you must shift to first gear with the clutch disengaged at least 5 seconds before the end of the idle period.  Note that this does not preclude vehicle designs involving engine operation with stop-start functions where the engine stops when the clutch is disengaged below a certain threshold speed and restarts upon reengagement of the clutch.
(4) Operate the vehicle with the appropriate accelerator pedal movement necessary to achieve the speed versus time relationship prescribed by the driving schedule.  Avoid smoothing speed variations and excessive accelerator pedal perturbations.
(5) Operate the vehicle smoothly, following representative shift speeds and procedures. For manual transmissions, the operator shall release the accelerator pedal during each shift and accomplish the shift with minimum time.  If the vehicle cannot accelerate at the specified rate, operate it at maximum available power until the vehicle speed reaches the value prescribed for that time in the driving schedule.
(6) Decelerate as follows:
(i) For vehicles with automatic transmission, use the brakes or accelerator pedal as necessary, without manually changing gears, to maintain the desired speed.
(ii) For vehicles with manual transmission, shift gears in a way that represents reasonable shift patterns for in-use operation, considering vehicle speed, engine speed, and any other relevant variables.  Disengage the clutch when the speed drops below 15 mph, when engine roughness is evident, or when good engineering judgment indicates the engine is likely to stall.  Manufacturers may recommend shift guidance in the owners manual that differs from the shift schedule during testing as long as both shift schedules are included in the application for certification.  In this case, we may use the shift schedule based on the shift pattern described in the owners manual.

§1066.425 Test preparation.
(a) Follow the procedures for PM sample preconditioning and tare weighing as described in 40 CFR 1065.590 if you need to measure PM emissions.
(b) For vehicles above 14,000 pounds GVWR with compression-ignition engines, verify the amount of nonmethane hydrocarbon contamination as described in 40 CFR 1065.520(g).
(c) Unless the standard-setting part specifies different tolerances, verify at some point before the test that ambient conditions are within the tolerances specified in this paragraph (c).  For purposes of this paragraph (c), "before the test" means any time from a point just prior to engine starting (excluding engine restarts) to the point at which emission sampling begins.
(1) Ambient temperature must be (20 to 30) °C.  See §1066.430(i) for circumstances under which ambient temperatures must remain within this range during the test.
(2) Dilution air conditions must meet the specifications in §1066.110(b)(2).  We recommend verifying dilution air conditions just before starting each test interval.
(d) Control test cell ambient air humidity as follows:
(1) For vehicles at or below 14,000 pounds GVWR, follow the humidity requirements in Table 1 of this section, unless the standard-setting part specifies otherwise.  When complying with humidity requirements in the table, where no tolerance is specified, use good engineering judgment to maintain the humidity level near the specified value within the limitations of your test facility.
(2) For vehicles above 14,000 pounds GVWR, you may test vehicles at any humidity.
Table 1 of §1066.425 - Test cell humidity requirements.
Test cycle
Humidity requirement    (grains H2O per pound dry air)
Tolerance (grains H2O per pound dry air)
AC17
69
+- 5 average,
+- 10 instantaneous
FTP[1] and LA-92
50

HFET
50

SC03
100
+- 5
US06
50

[1]FTP humidity requirement does not apply for cold (-7°C), intermediate (10 °C), and hot (35 °C) temperature testing.

(e) You may perform a final calibration of proportional-flow control systems, which may include performing practice runs.
(f) You may perform the following procedure to precondition sampling systems:
(1) Operate the vehicle over the test cycle.
(2) Operate any dilution systems at their expected flow rates.  Prevent aqueous condensation in the dilution systems as described in 40 CFR 1065.140(c)(6), taking into account allowances given in §1066.110(b)(2)(iv).
(3) Operate any PM sampling systems at their expected flow rates.
(4) Sample PM using any sample media.  You may change sample media during preconditioning.  You must discard preconditioning samples without weighing them.
(5) You may purge any gaseous sampling systems during preconditioning.
(6) You may conduct calibrations or verifications on any idle equipment or analyzers during preconditioning.
(g) Take the following steps before emission sampling begins:
(1) For batch sampling, connect clean storage media, such as evacuated bags or tare-weighed filters.
(2) Start all measurement instruments according to the instrument manufacturer's instructions and using good engineering judgment.
(3) Start dilution systems, sample pumps, and the data-collection system.
(4) Pre-heat or pre-cool heat exchangers in the sampling system to within their operating temperature tolerances for a test.
(5) Allow heated or cooled components such as sample lines, filters, chillers, and pumps to stabilize at their operating temperatures.
(6) Adjust the sample flow rates to desired levels using bypass flow, if desired.
(7) Zero or re-zero any electronic integrating devices before the start of any test interval.
(8) Select gas analyzer ranges.  You may not switch the gain of an analyzer's analog operational amplifier(s) during a test.  However, you may switch (automatically or manually) gas analyzer ranges during a test if such switching changes only the range over which the digital resolution of the instrument is applied.
(9) Zero and span all continuous gas analyzers using gases that meet the specifications of 40 CFR 1065.750.  For FID analyzers, you may account for the carbon number of your span gas either during the calibration process or when calculating your final emission value.  For example, if you use a C3H8 span gas of concentration 200 ppm (mol/mol), you may span the FID to respond with a value of 600 ppm (mol/mol) of carbon or 200 ppm of propane.  However, if your FID response is equivalent to propane, include a factor of three to make the final calculated hydrocarbon mass consistent with a molar mass of 13.875389.  When utilizing an NMC-FID, span the FID analyzer consistent with the determination of their respective response factors, RF, and penetration fractions, PF, according to 40 CFR 1065.365.
(10) We recommend that you verify gas analyzer responses after zeroing and spanning by sampling a calibration gas that has a concentration near one-half of the span gas concentration.  Based on the results, use good engineering judgment to decide whether or not to re-zero, re-span, or re-calibrate a gas analyzer before starting a test.
(11) If you correct for dilution air background concentrations of associated engine exhaust constituents, start sampling and recording background concentrations at the same time you start sampling exhaust gases.
(12) Turn on cooling fans immediately before starting the test.
(h) Proceed with the test sequence described in §1066.430.

§1066.430 Performing emission tests.
(a) See the standard-setting part for drive schedules.  These are defined by a smooth fit of a specified speed vs. time sequence.
(b) The driver must attempt to follow the target schedule as closely as possible, consistent with the specifications in paragraph (b) of this section.  Instantaneous speeds must stay within the following tolerances:
(1) The upper limit is 2.0 mph higher than the highest point on the trace within 1.0 s of the given point in time.
(2) The lower limit is 2.0 mph lower than the lowest point on the trace within 1.0 s of the given time.
(3) The same limits apply for vehicle operation without exhaust measurements, such as vehicle preconditioning and warm-up, except that the upper and lower limits for speed values are +-4.0 mph.  In addition, up to three occurrences of speed variations greater than the tolerance are acceptable for vehicle operation without exhaust measurements, as long as they occur for less than 15 seconds on any occasion and are clearly documented as to the time and speed at that point of the driving schedule.
(4) Void the test if you do not maintain speed values as specified in this paragraph (b), except as allowed by this paragraph (b)(4).  Speed variations (such as may occur during gear changes or braking spikes) may occur as follows, provided that such variations are clearly documented, including the time and speed values and the reason for the deviation:
(i) Speed variations greater than the specified limits are acceptable for up to 2.0 seconds on any occasion.
(ii) For vehicles that are not able to maintain acceleration as specified in §1066.420(e)(5), do not count the insufficient acceleration as being outside the specified limits.
(5) We may approve an alternate test cycle and cycle-validation criteria for vehicles that do not have enough power to follow the specified driving trace.  The alternate driving specifications must be based on making best efforts to maintain acceleration and speed to follow the specified test cycle.  We must approve these alternate driving specifications before you perform this testing.
(c) Figure 1 and Figure 2 of this section show the range of acceptable speed tolerances for typical points during testing.  Figure 1 of this section is typical of portions of the speed curve that are increasing or decreasing throughout the 2-second time interval.  Figure 2 of this section is typical of portions of the speed curve that include a maximum or minimum value.
         Figure 1 of §1066.430 -- Example of the allowable ranges for the driver's trace.
         Figure 2 of §1066.430 -- Example of the allowable ranges for the driver's trace.

(d) Start testing as follows:
(1) If a vehicle is already running and warmed up, and starting is not part of the test cycle, operate the vehicle as follows:
(i) For transient test cycles, control vehicle speeds to follow a drive schedule consisting of a series of idles, accelerations, cruises, and decelerations.
(ii) For cruise test cycles, control the vehicle operation to match the speed of the first interval of the test cycle.  Follow the instructions in the standard-setting part to determine how long to stabilize the vehicle during each interval, how long to sample emissions at each interval, and how to transition between intervals.
(2) If engine starting is part of the test cycle, start recording continuous data, any electronic integrating devices, and batch sampling before starting the engine.  Initiate the driver's trace when the engine starts.
(e) Perform the following at the end of each test interval, except as specified in subpart I of this part:
(i) Shut down the vehicle if it is part of the test cycle or if testing is complete.
(ii) Continue to operate all sampling and dilution systems to allow the response times to elapse.  Then stop all sampling and recording, including background sampling.  Finally, stop any integrating devices and indicate the end of the duty cycle in the recorded data.
(f) If testing involves engine shutdown followed by another test interval, start a timer for the vehicle soak when the engine shuts down.  Turn off cooling fans, close the vehicle hood (if applicable), and turn off the CVS or disconnect the exhaust tube from the tailpipe(s) of the vehicle unless otherwise instructed in the standard-setting part.  If testing is complete, disconnect the exhaust tube from the vehicle tailpipe(s) and drive the vehicle from dynamometer.
(g) Take the following steps after emission sampling is complete:
(1) For any proportional batch sample, such as a bag sample or PM sample, verify that proportional sampling was maintained according to 40 CFR 1065.545.  Void any samples that did not maintain proportional sampling according to those specifications.
(2) Place any used PM samples into covered or sealed containers and return them to the PM-stabilization environment.  Follow the PM sample post-conditioning and total weighing procedures in 40 CFR 1065.595.
(3) As soon as practical after the interval or test cycle is complete, or optionally during the soak period if practical, perform the following:
(i) Begin drift check for all continuous gas analyzers as described in paragraph (g)(6) of this section and zero and span all batch gas analyzers as soon as practical prior to any batch sample analysis.  You may perform this batch analyzer zero and span prior to the end of the test cycle or interval.
(ii) Analyze any conventional gaseous batch samples (HC, CH4, CO, NOx, and CO2) no later than 30 minutes after an interval or test cycle is complete, or during the soak period if practical.  Analyze background samples no later than 60 minutes after the test cycle is complete.
(iii) Analyze nonconventional gaseous batch samples (including background), such as NMHCE, N2O, or NMOG sampling with ethanol, as soon as practicable using good engineering judgment.
(4) Range validation.  If an analyzer operated above 100 % of its range at any time during the test, perform the following steps:
(i) For batch sampling, re-analyze the sample using the lowest analyzer range that results in a maximum instrument response below 100 %.  Report the result from the lowest range from which the analyzer operates below 100 % of its range.
(ii) For continuous sampling, repeat the entire test using the next higher analyzer range.  If the analyzer again operates above 100 % of its range, repeat the test using the next higher range.  Continue to repeat the test until the analyzer consistently operates at less than 100 % of its range. Keep records of any tests where the analyzer exceeds its range.  We may consider these results to be failures, consistent with good engineering judgment.
(5) After quantifying exhaust gases, verify drift as follows:
(i) For batch and continuous gas analyzers, record the mean analyzer value after stabilizing a zero gas to the analyzer.  Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response.
(ii) Record the mean analyzer value after stabilizing the span gas to the analyzer.  Stabilization may include time to purge the analyzer of any sample gas, plus any additional time to account for analyzer response.
(iii) Use these data to validate that analyzer drift does not exceed 2.0 % of the analyzer full scale.
(h) [Reserved]
(i) Measure and record ambient pressure.  Measure and record ambient temperature continuously to verify that it remains within the temperature range specified in §1066.425(c)(1) throughout the test.  Also measure humidity if required, such as for correcting NOx emissions, or meeting the requirements of §1066.425(d).
 (j) For vehicles at or below 14,000 pounds GVWR, determine overall driver accuracy as follows:
 (1) Compare the following drive cycle metrics, based on measured vehicle speeds, to a reference value based on the target cycle that would have been generated by driving exactly to the target trace as described in SAE J2951 (incorporated by reference in §1066.1010).
 (i) Determine the Energy Economy Rating as described in Section 5.4 of SAE J2951.
 (ii) Determine the Absolute Speed Change Rating as described in Section 6.1.2 of SAE J2951.
 (iii) Calculate the Inertia Work Rating, IR, using the both the sums of the incremental driven and the target inertia work as described in Eq. 1066.430-1.

			Eq. 1066.430-1
Where:
 = the driven inertial force over an interval i, as described by Equation 18 of SAE J2951.
= the target inertial force over an interval j, as described by Equation 19 of SAE J2951.
= the incremental driven distance over an interval i, as described by Equation 12 of SAE J2951.
= the incremental target distance over an interval j, as described by Equation 13 of SAE J2951.
 (2) The standard-setting part may require you to provide to us 10 Hz data to characterize both target and actual values for cycle energy.  Calculate target values based on the vehicles speeds from the specified test cycle.

 Subpart F -- Hybrids and Electric Vehicles
§1066.501 Overview.
For HEV, PHEV, and pure electric vehicle (EV), use the following procedures:
(a) Correct the results for Net Energy Change of the RESS as follows:
(1) For vehicles at or below 14,000 pounds GVWR, follow SAE J1711 (incorporated by reference in §1066.1010) except as noted in this paragraph (a).  Use +-1 % of reading or +-0.3 % of full scale, whichever is greater, in place of the current measurement accuracy in Section 4.2a of SAE J1711.
(2) For vehicles above 14,000 pounds GVWR, follow SAE J2711 (incorporated by reference in §1066.1010) for requirements related to charge-sustaining operation.
(3) For pure EVs, irrespective of GVWR, follow SAE J1634 (incorporated by reference in §1066.1010).
(b) This paragraph (b) applies for vehicles that include an engine-powered generator or other auxiliary power unit that provides motive power.  For example, this would include a vehicle that has a small gasoline engine that generates electricity to charge batteries.  Unless we approve otherwise, measure emissions for all test cycles when such an engine is operating.  For each test cycle for which emissions are not measured, you must validate that such engines are not operating at any time during the test cycle.

Subpart G -- Calculations
§1066.601 Overview.
(a) This subpart describes calculations used to determine emission rates.  See the standard setting part and the other provisions of this part to determine which equations apply for your testing.  This subpart describes how to -
(1) Use the signals recorded before, during, and after an emission test to calculate distance-specific emissions of each regulated pollutant.
(2) Perform calculations for calibrations and performance checks.
(3) Determine statistical values.
(b) You may use data from multiple systems to calculate test results for a single emission test, consistent with good engineering judgment.  You may also make multiple measurements from a single batch sample, such as multiple weighing of a PM filter or multiple readings from a bag sample.  Although you may use an average of multiple measurements from a single test, you may not use test results from multiple emission tests to report emissions.  We allow weighted means where appropriate, such as for sampling onto a PM filter over the FTP.  You may discard statistical outliers, but you must report all results.

§1066.610 Mass-based and molar-based exhaust emission calculations.
(a) Calculate your total mass of emissions over a test cycle as specified in paragraph (c) of this section or in 40 CFR part 1065, subpart G, as applicable.
(b) For composite emission calculations over multiple test intervals and corresponding weighting factors, see the standard-setting part.
(c) To calculate total mass emissions, multiply a concentration by its respective flow and density as specified in Eq. 1066.610-1.  Before calculating mass emissions as specified in paragraph (d) and (e) of this section, perform the following sequence of preliminary calculations to correct recorded concentration measurements:
(1) For vehicles above 14,000 pounds GVWR, correct all THC and CH4 concentrations for initial contamination as described in 40 CFR 1065.660(a), including continuous readings, sample bag readings, and dilution air background readings.  This correction is optional for vehicles at or below 14,000 pounds GVWR.
(2) Correct all concentrations measured on a "dry" basis to a "wet" basis, including dilution air background concentrations.
(3) Calculate all NMHC and CH4 concentrations, including dilution air background concentrations, as described in 40 CFR 1065.660.
(4) For vehicles at or below 14,000 pounds GVWR, calculate HC concentrations, including dilution air background concentrations, as described in this section and §1066.665 for NMOG.  For emission testing of vehicles above 14,000 pounds GVWR, with fuels that contain 25% or more oxygenated compounds by volume, calculate HC concentrations, including dilution air background concentrations, as described in 40 CFR part 1065, subpart I, for THCE and NMHCE.
(5) Correct all NOx emission values for test cell ambient air humidity as described in §1066.630.
(6) Correct all gaseous concentrations for dilution air background as described in §1066.620.
(7) Correct all PM filter masses for sample media buoyancy as described in 40 CFR 1065.690.
(d) Calculate the emission mass of each gaseous pollutant using the following equation:

			Eq. 1066.610-1
Where:
m[emission] = emission mass over the test interval.
Vmix = total dilute exhaust volume over the test interval at standard reference conditions, corrected for any volume removed for emission sampling and the addition of secondary dilution air (if applicable).
ρ[emission] = density of the appropriate chemical species as given in §1066.1005(f).
x[emission] = measured emission concentration in the sample, after dry-to-wet and background corrections.
c = 10[-2] for emission concentrations % and 10[-6] for emission concentrations in ppm.

Example:
Vmix = 170.878 m[3] (from paragraph (f) of this section)
ρNOx = 1913 g/m[3]
xNOx = 0.9721 ppm
c = 10[-6]

(e) The calculation of PM is dependent on how many PM filters are used (for example as described in §1066.822(b)), as follows:
(1) Except as specified in paragraphs (e)(2) and (3) of this section, calculate mPM using the following equation:

				Eq. 1066.610-2
Where:
mPM = mass of particulate matter emissions over the test interval, as described in §1066.820(b)(1), (2), and (3).
Vmix = total dilute exhaust volume over the test interval at standard reference conditions , corrected for any volume removed for emissions sampling and the addition of secondary dilution air (if applicable).
Vsdastd = total volume of secondary dilution air flow sampled through the filter over the test phase at standard temperature and pressure.
mPMfil = mass of particulate matter emissions on the filter over the test interval.
mPMbkgnd = mass of particulate matter on the background filter.

Example:
Vmix = 170.878 m[3] (from paragraph (f) of this section)
VPMstd = 0.925 m[3] (from paragraph (f) of this section)
Vsdastd = 0.527 m[3] (from paragraph (f) of this section)
mPMfil = 0.0000045 g
mPMbkgnd = 0.0000014 g

(2) If you sample PM onto a single filter as described in §1066.820(b)(4), calculate mPM using the following equation:

			Eq. 1066.610-3
Where:
mPM = mass of particulate matter emissions over the entire FTP as sampled according to §1066.820(b)(4).
Vmix = total dilute exhaust volume over the test interval at standard reference conditions, corrected for any volume removed for emissions sampling and the addition of secondary dilution air (if applicable).
V[interval]-PMstd = total volume of dilute exhaust sampled through the filter over the test interval (ct = cold transient, s = stabilized, ht = hot transient) at standard reference conditions.
V[interval]-sdastd = total volume of secondary dilution air sampled through the filter over the test interval (ct = cold transient, s = stabilized, ht = hot transient) at standard reference conditions.
mPMfil = mass of particulate matter emissions on the filter over the test interval.
mPMbkgnd = mass of particulate matter on the background filter.

Example:
Vmix = 633.691 m[3]
Vct-PMstd = 0.925 m[3]
Vct-sdastd = 0.527 m[3]
Vs-PMstd = 1.967 m[3]
Vs-sdastd = 1.121 m[3]
Vht-PMstd = 1.122 m[3]
Vht-sdastd = 0.639 m[3]
mPMfil = 0.0000106 g
mPMbkgnd = 0.0000014 g

mPM = 0.00222 g

(3) If you sample PM onto a single filter as described in §1066.820(b)(5), calculate mPM using the following equation:

				Eq. 1066.610-4
Where:
mPM = mass of particulate matter emissions over the entire FTP as sampled according to §1066.820(b)(5).
Vmix = total dilute exhaust volume over the test interval at standard reference conditions, corrected for any volume removed for emissions sampling and the addition of secondary dilution air (if applicable).
V[interval]-PMstd = total volume of dilute exhaust sampled through the filter over the test interval (ct = cold transient, cs = cold stabilized, ht = hot transient, hs = hot stabilized) at standard reference conditions.
V[interval]-sdastd = total volume of secondary dilution air sampled through the filter over the test interval (ct = cold transient, cs = cold stabilized, ht = hot transient, hs = hot stabilized) at standard reference conditions.
mPMfil = mass of particulate matter emissions on the filter over the test interval.
mPMbkgnd = mass of particulate matter on the background filter.

Example:
Vmix = 972.121 m[3]
Vct-PMstd = 0.925 m[3]
Vct-sdastd = 0.529 m[3]
Vcs-PMstd = 1.968 m[3]
Vcs-sdastd = 1.123 m[3]
Vht-PMstd = 1.122 m[3]
Vht-sdastd = 0.641 m[3]
Vhs-PMstd = 1.967 m[3]
Vhs-sdastd = 1.121 m[3]
mPMfil = 0.0000229 g
mPMbkgnd = 0.0000014 g

mPM = 0.00155 g

(f) This paragraph (f) describes how to correct flow and flow rates to standard reference conditions and provides an example for determining Vmix based on CVS total flow and the removal of sample flow from the dilute exhaust gas.
(1) Correct flow and flow rates to standard reference conditions as needed using the following equation:

				Eq. 1066.610-5
Where:
V[flow]std = total volume of flow at the flow meter at standard reference conditions.
V[flow]act = total volume of flow at the flow meter at test conditions.
pin = absolute static pressure at the flow meter inlet, measured directly or calculated as the sum of atmospheric pressure plus a differential pressure referenced to atmospheric pressure.
Tstd = standard temperature.
pstd = standard pressure.
Tin = average temperature of the dilute exhaust sample at the flow meter inlet.

Example:
VPMact = 1.071 m[3]
pin = 101.7 kPa
Tstd = 293.15 K
pstd = 101.325 kPa
Tin = 340.5 K

(2) The following example provides a determination of Vmix based on CVS total flow and the removal of sample flow from one dilute exhaust gas analyzer and one PM sampling system that is utilizing secondary dilution.  Note that your Vmix determination may vary from Eq. 1066.610-6 based on the number of flows that are removed from your dilute exhaust gas and whether your PM sampling system is using secondary dilution.  For this example, Vmix is governed by the following equation:

				Eq. 1066.610-6
Where:
VCVSstd = total dilute exhaust volume over the test interval at the flow meter at standard reference conditions.
Vgasstd = total volume of sample flow through the gaseous emission bench over the test interval at standard reference conditions.
VPMstd = total volume of dilute exhaust sampled through the filter over the test interval at standard reference conditions.
Vsdastd = total volume of secondary dilution air flow sampled through the filter over the test interval at standard reference conditions.

Example:
Using Eq. 1066.610-5
VCVSstd = 170.451 m[3], where VCVSact = 170.721 m[3], pin = 101.7 kPa, and Tin = 294.7 K
Using Eq. 1066.610-5
Vgasstd = 0.028 m[3], where Vgasact = 0.033 m[3], pin = 101.7 kPa, and Tin = 340.5 K
Using Eq. 1066.610-5
VPMstd = 0.925 m[3], where VPMact = 1.071 m[3], pin = 101.7 kPa, and Tin = 340.5 K
Using Eq. 1066.610-5
Vsdastd = 0.527 m[3], where Vsdaact = 0.531 m[3], pin = 101.7 kPa, and Tin = 296.3 K
Vmix = 170.451 + 0.028 + 0.925  -  0.527 = 170.878 m[3]
(g) Total sample volume over a test interval.  Calculate total flow, V[flow], for a CVS or exhaust gas sampler as follows:
(1) Varying versus constant flow rates. The calculation methods depend on differentiating varying and constant flow, as follows:
(i) We consider the following to be examples of varying flows that require a continuous multiplication of concentration times volumetric flow rate: raw exhaust, exhaust diluted with a constant flow rate of dilution air, and CVS dilution with a CVS flow meter that does not have an upstream heat exchanger or electronic flow control.
(ii) We consider the following to be examples of constant exhaust flows: CVS diluted exhaust with a CVS flow meter that has an upstream heat exchanger, an electronic flow control, or both.
(2) Continuous sampling.  For continuous sampling, you must frequently record a continuously updated flow signal.  This recording requirement applies for both varying and constant flow rates.
(i) Varying flow rate.  If you continuously sample from a varying exhaust flow rate, calculate V[flow] using the following equation:

		Eq. 1066.610-7

Where:
∆t = 1/frecord  	Eq. 1066.610-8

Example:
N = 505
= 0.276 m[3]/s
= 0.294 m[3]/s
frecord = 1 Hz
Using Eq. 1066.610-8,
t = 1/1 = 1 s

VCVS = 170.721 m[3]
(ii) Constant flow rate.  If you continuously sample from a constant exhaust flow rate, use the same calculation described in paragraph (g)(2)(i) of this section or calculate the mean flow recorded over the test interval and treat the mean as a batch sample, as described in paragraph (g)(3)(ii) of this section.
(3) Batch sampling. For batch sampling, calculate total flow by integrating a varying flow rate or by determining the mean of a constant flow rate, as follows:
(i) Varying flow rate.  If you proportionally collect a batch sample from a varying exhaust flow rate, integrate the flow rate over the test interval to determine the total flow from which you extracted the proportional sample, as described in paragraph (g)(2)(i) of this section.
(ii) Constant flow rate.  If you batch sample from a constant exhaust flow rate, extract a sample at a proportional or constant flow rate and calculate V[flow] from the flow from which you extract the sample by multiplying the mean flow rate by the time of the test interval using the following equation:

Eq. 1066.610-9
Example:
= 0.338 m[3]/s
t = 505 s

VCVS = 170.69 m[3]

§1066.620 Dilution air background correction.
(a) Correct the emissions in a gaseous sample for background using the following equation:

				Eq. 1066.620-1
Where:
x[emission]dexh = measured emission concentration in dilute exhaust (after dry-to-wet correction for dry measurements).
x[emission]bkgnd = measured emission concentration in the dilution air (after dry-to-wet correction for dry measurements).
DF = dilution factor determined in paragraph (b) of this section.

Example:
xNOxdexh = 1.08305 ppm
xNOxbkgnd = 0.12456 ppm
DF = 9.14506

(b) Determine the dilution factor, DF, over the test interval using the following equation:

                              Eq. 1066.620-2
Where:
xCO2 = amount of CO2 measured in the sample over the test interval.
xNMHC = amount of C1-equivalent NMHC measured in the sample over the test interval.
xCH4 = amount of CH4 measured in the sample over the test interval.
xCO = amount of CO measured in the sample over the test interval.
 = atomic hydrogen-to-carbon ratio of the test. You may measure  or use default values from Table 1 of 40 CFR 1065.655.
 = atomic oxygen-to-carbon ratio of the test fuel.  You may measure  or use default values from Table 1 of 40 CFR 1065.655.

Example:
xCO2 = 1.456 % = 0.01456
xNMHC = 0.84 ppm = 0.00000084
xCH4 = 0.26 ppm = 0.00000026
xCO = 80.4 ppm = 0.0000804
 = 1.92
 = 0.03

(c) Determine the dilution factor, DF, over the test interval for partial-flow dilution sample systems that measure PM using the following equation:

		Eq. 1066.620-3
Where:
VPMstd = total dilute exhaust volume sampled through the filter over the test interval at standard reference conditions.
Vexhstd = total exhaust volume sampled from the vehicle at standard reference conditions.

Example:
VPMstd = 170.9 m[3]
Vexhstd = 15.9 m[3]

(d) Determine the time-weighted dilution factor, DFw, over the duty cycle using the following equation:

		Eq. 1066.620-4
Where:
N = number of test intervals.
i = test interval number
t = duration of the test interval.
DF = dilution factor over the test interval.

Example:
N = 3
DF1 = 14.40
t1 = 505 s
DF2 = 24.48
t2 = 867 s
DF3 = 17.28
t3 = 505 s

§1066.630 NOx intake-air humidity correction.
See the standard-setting part to determine if you may correct NOx emissions for the effects of intake-air humidity.  Correct NOx emissions for intake-air humidity as described in this section.  See §1066.610(c)(1) for the proper sequence for applying the NOx intake-air humidity correction.
(a) For vehicles at or below 14,000 pounds GVWR, apply a correction for any reciprocating engines for the following test cycles:
(1) Calculate a humidity correction using a time-weighted mean value for ambient humidity over the test interval.  Calculate absolute ambient humidity in grams H2O vapor per kilogram of dry air using the following equation:

                  	Eq. 1066.630-1
Where:
MH2O = molar mass of H2O, in g/mol.
pd = saturated vapor pressure at the ambient dry bulb temperature, in kPa.
RH%  = relative humidity of ambient air, in %.
Mair = molar mass of air, in g/mol.
patmos = atmospheric pressure, in kPa.

Example:
MH2O = 18.01528 g/mol
pd = 2.93 kPa
RH % = 37.5 %
Mair = 28.96559 g/mol
patmos = 96.71 kPa

(2) Use the following equation to correct measured concentrations to a reference condition of 10.71 grams H2O vapor per kilogram of dry air for the FTP, US06, LA-92, SC03, and HFET test cycles:

                  	Eq. 1066.630-2
Where:
xNOxdexh = measured dilute NOx emissions.
Hs = humidity scale.  Set = 1 for FTP, US06, LA-92, and HFET test cycles.  Set = 0.8825 for the SC03 test cycle.
H = absolute humidity, from paragraph (a)(1) of this section.

Example:
H = 7.14741 g H2O vapor/kg dry air
xNOxdexh = 1.21 ppm

(b) For vehicles above 14,000 pounds GVWR, apply correction factors as described in 40 CFR 1065.670.

§1066.640 Removed water correction.
Correct for removed water if water removal occurs upstream of a concentration measurement and downstream of a flow meter used to determine mass emissions over a test interval.  Perform this correction based on the amount of water at the concentration measurement and on the amount of water at the flow meter.

§1066.650 Flow meter calibration calculations.
This section describes how to calibrate various flow meters based on mass flow rates.  Calibrate your flow meter according to 40 CFR 1065.640 instead if you calculate emissions based on molar flow rates.
(a) PDP calibration calculations. Perform the following steps to calibrate a PDP flow meter:
(1) Calculate PDP volume pumped per revolution, Vrev, for each restrictor position from the mean values determined in §1066.140:

                  Eq. 1066.650-1
Where:
= mean flow rate of the reference flow meter.
 = mean temperature at the PDP inlet.
pstd = standard pressure = 101.325 kPa.
= mean PDP speed.
 = mean static absolute pressure at the PDP inlet.
Tstd = standard temperature = 293.15 K.

Example:
 = 0.1651 m[3]/s
= 299.5 K
pstd = 101.325 kPa
= 1205.1 r/min = 20.085 r/s
= 98.290 kPa
Tstd = 293.15 K

Vrev = 0.00866 m[3]/r

(2) Calculate a PDP slip correction factor, Ks for each restrictor position from the mean values determined in §1066.140:

                  Eq. 1066.650-2
Where:
= mean PDP speed.
 = mean static absolute pressure at the PDP outlet.
 = mean static absolute pressure at the PDP inlet.

Example:
= 1205.1 r/min = 20.085 r/s
= 100.103 kPa
= 98.290 kPa

Ks = 0.006700 s/r
(3) Perform a least-squares regression of Vrev, versus PDP Ks, by calculating slope, a1, and intercept, a0, as described in 40 CFR 1065.602.
(4) Repeat the procedure in paragraphs (a)(1) through (3) of this section for every speed that you run your PDP.
(5) The following example illustrates a range of typical values for different PDP speeds:
Table 1 of §1066.650 -
Example of PDP calibration data

(r/s)
a1        (m[3]/s)
a0        (m[3]/r)
12.6
0.841
0.056
16.5
0.831
-0.013
20.9
0.809
0.028
23.4
0.788
-0.061

(6) For each speed at which you operate the PDP, use the appropriate regression equation from this paragraph (a) to calculate flow rate during emission testing as described in §1066.652.
(b) SSV calibration.  The equations governing SSV flow assume one-dimensional isentropic inviscid flow of an ideal gas, except that the equations can account for compressible flow.  Paragraph (b)(2)(iv) of this section describes other assumptions that may apply.  If good engineering judgment dictates that you account for gas compressibility, you may either use an appropriate equation of state to determine values of Z as a function of measured pressure and temperature, or you may develop your own calibration equations based on good engineering judgment.  Note that the equation for the flow coefficient, Cf, is based on the ideal gas assumption that the isentropic exponent, , is equal to the ratio of specific heats, Cp/Cv.  If good engineering judgment dictates using a real gas isentropic exponent, you may either use an appropriate equation of state to determine values of  as a function of measured pressure and temperature, or you may develop your own calibration equations based on good engineering judgment.
 (1) Calculate volumetric flow rate, , as follows:

                  Eq. 1066.650-3
Where:
Cd = discharge coefficient, as determined in paragraph (b)(2)(i) of this section.
Cf = flow coefficient, as determined in paragraph (b)(2)(ii) of this section.
At = cross-sectional area at the venturi throat.
R = molar gas constant.
pin = static absolute pressure at the venturi inlet.
Tstd = standard temperature.
pstd = standard pressure.
Z = compressibility factor.
Mmix = molar mass of gas mixture.
Tin = absolute temperature at the venturi inlet.

(2) Perform the following steps to calibrate an SSV flow meter:
(i) Using the data collected in §1066.140, calculate Cd for each flow rate using the following equation:

            Eq. 1066.650-4
Where:
= measured volumetric flow rate from the reference flow meter.
(ii) Use the following equation to calculate Cf  for each flow rate:

            Eq. 1066.650-5
Where:
 = isentropic exponent.  For an ideal gas, this is the ratio of specific heats of the gas mixture, Cp/Cv.
r = pressure ratio, as determined in paragraph (b)(2)(iii) of this section.
 = ratio of venturi throat diameter to inlet diameter.
(iii) Calculate r using the following equation:

            Eq. 1066.650-6
Where:
p = differential static pressure, calculated as venturi inlet pressure minus venturi throat pressure.

(iv) You may apply any of the following simplifying assumptions or develop other values as appropriate for your test configuration, consistent with good engineering judgment:
(A) For raw exhaust, diluted exhaust, and dilution air, you may assume that the gas mixture is incompressible and therefore behaves as an ideal gas (Z=1).
(B) For raw exhaust, you may assume =1.385.
(C) For diluted exhaust and dilution air, you may assume =1.399.
(D) For diluted exhaust and dilution air, you may assume Mmix is a function only of the amount of water in the dilution air or calibration air, xH2O, as follows:

            Eq. 1066.650-7
Where:
Mair = 28.964 g/mol
xH2O = amount of H2O in the dilution air, determined as described in 40 CFR 1065.645.
MH20 = 18.015 g/mol

Example:
xH2O = 0.0169 mol/mol

Mmix = 28.7789 g/mol
(E) For diluted exhaust and dilution air, you may assume a constant molar mass of the mixture, Mmix, for all calibration and all testing if you control the amount of water in calibration air and in dilution air, as shown in the following table:

                           Table 2 of §1066.650 -
                 Examples of dilution air and calibration air
              dewpoints at which you may assume a constant Mmix.
If calibration Tdew (C) is...
assume the following constant Mmix (g/mol)...
for the following ranges of Tdew (C) during emission tests[a]
< 0
28.96559
< 18
0
28.89263
< 21
5
28.86148
< 22
10
28.81911
< 24
15
28.76224
 < 26
20
28.68685
-8 to 28
25
28.58806
12 to 31
30
28.46005
23 to 34
[a]The specified ranges are valid for all calibration and emission testing over the atmospheric pressure range (80.000 to 103.325) kPa.

(v) The following example illustrates the use of the governing equations to calculate Cd of an SSV flow meter at one reference flow meter value:

Example:
= 2.395 m[3]/s
Z = 1
Mmix = 28.7789 g/mol = 0.0287789 kg/mol
R = 8.314472 J/(mol∙K) = 8.314472 (m[2]∙kg)/(s[2]∙mol∙K)
Tin = 298.15 K
At = 0.01824 m[2]
pin = 99.132 kPa = 99132 Pa = 99132 kg/(m∙s[2])
 = 1.399
  = 0.8
p = 2.312 kPa

Cf = 0.274

Cd = 1.695
(vi) Calculate the Reynolds number, Re[#], for each reference volumetric flow rate, , using the throat diameter of the venturi, dt, and the uncorrected air density, .  Because the dynamic viscosity, , is needed to compute Re[#], you may use your own fluid viscosity model to determine for your calibration gas (usually air), using good engineering judgment.  Alternatively, you may use the Sutherland three-coefficient viscosity model to approximate , as shown in the following sample calculation for Re[#]:

      Eq. 1066.650-8
Where, using the Sutherland three-coefficient viscosity model:

            Eq. 1066.650-9
Where:
0 = Sutherland reference viscosity.
T0 = Sutherland reference temperature.
S = Sutherland constant.

                           Table 3 of §1065.640 -
            Sutherland three-coefficient viscosity model parameters
Gas[a]

0
T0
S
Temp range within +-2 % error[b]
Pressure limit[b]

kg /(m∙s)
K
K
K
kPa
Air
1.716∙10[-5]
273
111
170 to 1900
<= 1800
CO2
1.370∙10[-5]
273
222
190 to 1700
<= 3600
H2O
1.12∙10[-5]
350
1064
360 to 1500
<= 10000
O2
1.919∙10[-5]
273
139
190 to 2000
<= 2500
N2
1.663∙10[-5]
273
107
100 to 1500
<= 1600
[a]Use tabulated parameters only for the pure gases, as listed.  Do not combine parameters in calculations to calculate viscosities of gas mixtures.
[b]The model results are valid only for ambient conditions in the specified ranges.

Example:
0 = 1.716∙10[-5] kg/(m∙s)
T0 = 273 K
S = 111 K

 = 1.838∙10[-5] kg/(m∙s)
Tin = 298.15 K
dt = 152.4 mm = 0.1524 m
 = 1.1508 kg/m[3]

Re[#] = 1.2531∙10[6]
(vii) Calculate ρ using the following equation:

      Eq. 1066.650-10

Example:

ρ = 1.1508 kg/m[3]
(viii) Create an equation for Cd as a function of Re[#], using paired values of the two quantitites.  The equation may involve any mathematical expression, including a polynomial or a power series.  The following equation is an example of a commonly used mathematical expression for relating Cd and Re[#]:

      Eq. 1066.650-11
(ix) Perform a least-squares regression analysis to determine the best-fit coefficients for the equation and calculate the equation's regression statistics, SEE and r[2], according to §1065.602.
(x) If the equation meets the criteria of SEE <= (0.5 % · ) and r[2] >= 0.995, you may use the equation to determine Cd for emission tests, as described in §1065.642.
(xi)  If the equation does not meet the specified statistical criteria, you may use good engineering judgment to omit calibration data points; however, you must use at least seven calibration data points to demonstrate that you meet the criteria.  For example, this may involve narrowing the range of flow rates for a better curve fit.
(xii) Take corrective action if the equation does not meet the specified statistical criteria even after omitting calibration data points.  For example, select another mathematical expression for the Cd versus Re[#] equation, check for leaks, or repeat the calibration process.  If you must repeat the calibration process, we recommend applying tighter tolerances to measurements and allowing more time for flows to stabilize.
(xiii) Once you have an equation that meets the specified statistical criteria, you may use the equation only for the corresponding range of flow rates.
(c) CFV calibration.  Some CFV flow meters consist of a single venturi and some consist of multiple venturis, where different combinations of venturis are used to meter different flow rates.  For CFV flow meters that consist of multiple venturis, either calibrate each venturi independently to determine a separate calibration coefficient, Kv, for each venturi, or calibrate each combination of venturis as one venturi by determining Kv for the system.
(1) To determine Kv for a single venturi or a combination of venturis, perform the following steps:
(i) Calculate an individual Kv for each calibration set point for each restrictor position using the following equation:

                  Eq. 1066.650-12
Where:
 = mean flow rate from the reference flow meter, at standard reference conditions.
 = mean temperature at the venturi inlet.
 = mean static absolute pressure at the venturi inlet.

(ii) Calculate the mean and standard deviation of all the Kv values (see 40 CFR 1065.602).  Verify choked flow by plotting Kv as a function of .Kv will have a relatively constant value for choked flow; as vacuum pressure increases, the venturi will become unchoked and Kv will decrease.  Paragraphs (c)(1)(iii) through (viii) of this section describe how to verify your range of choked flow.
(iii) If the standard deviation of all the Kv values is less than or equal to 0.3 % of the mean Kv, use the mean Kv in Eq. 1066.652-7, and use the CFV only up to the highest venturi pressure ratio, r, measured during calibration using the following equation:

                  Eq. 1066.650-13
Where:
pCFV = differential static pressure; venturi inlet minus venturi outlet.

(iv) If the standard deviation of all the Kv values exceeds 0.3 % of the mean Kv, omit the Kv value corresponding to the data point collected at the highest rmeasured during calibration.
(v) If the number of remaining data points is less than seven, take corrective action by checking your calibration data or repeating the calibration process.  If you repeat the calibration process, we recommend checking for leaks, applying tighter tolerances to measurements and allowing more time for flows to stabilize.
(vi) If the number of remaining Kv values is seven or greater, recalculate the mean and standard deviation of the remaining Kv values.
(vii) If the standard deviation of the remaining Kv values is less than or equal to 0.3 % of the mean of the remaining Kv, use that mean Kv in Eq 1066.652-7, and use the CFV values only up to the highest rassociated with the remaining Kv.
(viii) If the standard deviation of the remaining Kv still exceeds 0.3 % of the mean of the remaining Kv values, repeat the steps in paragraph (c)(1)(iv) through (vii) of this section.
(2) During exhaust emission tests, monitor sonic flow in the CFV by monitoring the CFV pressure ratio.  Based on the calibration data selected to meet the criteria for paragraphs (c)(1)(iv) and (vii) of this section, in which Kv is constant, select the data values associated with the calibration point with the lowest absolute venturi inlet pressure to determine the r limit.  Calculate r during the exhaust emission test using Eq. 1066.650-8 to demonstrate that the value of r during all emission tests is less than or equal to the r limit derived from the CFV calibration data.

§1066.652 PDP, SSV, and CFV flow rate calculations.
This section describes the equations for calculating flow rates from various flow meters.  After you calibrate a flow meter according to §1066.650, use the calculations described in this section to calculate flow during an emission test.  Calculate flow according to 40 CFR 1065.642 instead if you calculate emissions based on molar flow rates.
(a) PDP volumetric flow rate.  Based upon the speed at which you operate the PDP for a test interval, select the corresponding slope, a1, and intercept, a0, as calculated in §1066.650(a), to calculate volumetric flow rate,  as follows:

                  Eq. 1066.652-1
Where:
fnPDP = pump speed.
Vrev = PDP volume pumped per revolution.
Tstd = standard temperature = 293.15 K.
pin = static absolute pressure at the PDP inlet.
Tin = pump inlet absolute temperature.
pstd = standard pressure= 101.325 kPa.
= static absolute pressure at the PDP outlet.

                  Eq. 1066.652-2

Example:
a1 = 50.43 m[3]/min = 0.8405 m[3]/s
fnPDP = 755.0 r/min = 12.58 r/s
pout = 99.950 kPa
pin = 98.575 kPa
a0 = 0.056 m[3]/r
Tin = 323.5 K

Vrev = 0.063 m[3]/r

= 0.7079 m[3]/s
(b) SSV volumetric flow rate.  Calculate SSV volumetric flow rate during an emission test, , as follows:

            Eq. 1066.652-3
Where:
Cd = discharge coefficient, as determined based on the Cd versus Re[#] equation in §1066.650(b)(2)(viii).
Cf = flow coefficient, as determined in §1066.650 (b)(2)(ii).
At = venturi throat cross-sectional area.
R = molar gas constant.
pin = static absolute pressure at the venturi inlet.
Tstd = standard temperature.
pstd = standard pressure.
Z = compressibility factor.
Mmix = molar mass of gas mixture.
Tin = absolute temperature at the venturi inlet.

Example:
Cd = 0.890
Cf = 0.274
At = 0.01824 m[2]
R = 8.314472 J/(mol∙K) = 8.314472 (m[2]∙kg)/(s[2]∙mol∙K)
pin = 98.496 kPa
Tstd = 293.15 K
pstd = 101.325 kPa
Z = 1
Mmix = 28.7789 g/mol = 0.0287789 kg/mol
Tin = 296.85 K

 = 1.252 m[3]/s
 (c) CFV volumetric flow rate.  Some CFV flow meters consist of a single venturi and some consist of multiple venturis, where different combinations of venturis are used to meter different flow rates.  If you use multiple venturis and you calibrated each venturi independently to determine a separate calibration coefficient, Kv, for each venturi, calculate the individual volumetric flow rates through each venturi and sum all their flow rates to determine.  If you use multiple venturis and you calibrated each combination of venturis, calculate using the Kv that was determined for that combination of venturis.
(1) To calculate volumetric flow rate through one venturi or a combination of venturis, use the mean Kv you determined according to §1066.650(c) and calculate the appropriate volumetric flow rate, , during an emission test as follows:

                  Eq. 1066.652-7
Where:
 = air flow rate of flow meter, in m[3]/s.
Kv = flow meter calibration coefficient, in m[3]∙K[1/2]/(kPa∙s).
Tin = temperature at the venturi inlet, in K.
pin = absolute static pressure at the venturi inlet, in kPa.

Example:
Kv = 0.074954 m[3]∙K[1/2]/(kPa∙s)
pin = 99.654 kPa
Tin = 353.15 K

 = 0.39748 m[3]/s

§1066.665 NMOG determination.
For vehicles subject to an NMOG standard, determine NMOG as described in paragraph (a) of this section.  Except as specified in the standard-setting part, you may alternatively calculate NMOG results based on measured NMHC emissions as described in paragraphs (c) through (f) of this section.
(a) Determine NMOG by independently measuring alcohols and carbonyls as described in 40 CFR 1065.805 and 1065.845.  Use good engineering judgment to determine which alcohols and carbonyls you need to measure.  This would typically require you to measure all alcohols and carbonyls that you expect to contribute 1% or more of total NMOG emissions.  Calculate NMOG with the following equation, using density values specified in §1066.1005(f):

            Eq. 1066.665-1
Where:
mNMOG = the sum of the mass of NMOG in the exhaust.
mNMHC = the mass of NMHC and all oxygenated hydrocarbons (OHCs) in the exhaust, as determined using Eq. 1066.610-1.  Calculate NMHC mass based on ρNMHC.
ρNMHC = the effective C1-equivalent density of NMHC as specified in §1066.1005(f):.
mOHCi = the mass of oxygenated species i in the exhaust calculated using Eq. 1066.610-1.
ρOCHi = the C1-equivalent density of oxygenated species i.
RFOHCi[THC-FID] = The response factor of a THC-FID to oxygenated species i relative to propane on a C1-equivalent basis as determined in 40 CFR 1065.665.
(b) The following example shows how to determine NMOG emissions as described in paragraph (a) of this section for (OHC) compounds including ethanol (C2H5OH), methanol (CH3OH), acetaldehyde (C2H4O), and formaldehyde (C2HO) as C1-equivalent concentrations:
mNMHC = 0.0125 g
mCH3OH = 0.0002 g
mC2H5OH = 0.0009 g
mHCHO = 0.0001 g
mC2H4O = 0.00005 g
RFCH3OH[THC-FID] = 0.63
RFC2H5OH[THC-FID] = 0.75
RFHCHO[THC-FID] = 0.00
RFC2H4O[THC-FID] = 0.50
ρNMHC-liq = 576.816 g/m[3]
ρCH3OH = 1332.02 g/m[3]
ρC2H5OH = 957.559 g/m[3]
ρHCHO = 1248.21 g/m[3]
ρC2H4O = 915.658 g/m[3]

mNMOG = 0.013273
(c) For ethanol-gasoline blends less than 25 % ethanol by volume, you may calculate NMOG emissions from measured NMHC emissions as follows:
(1) For hot-start and hot running test cycles or intervals other than the FTP, you may determine NMOG based on the test cycle NMHC emission rate using the following equation:

            Eq. 1066.665-2
Where:
eNMOGhot = mass emission rate of NMOG over the hot running test cycle.
eNMHChot = mass emission rate of NMHC over the hot running test cycle, calculated using ρNMHC-liq.

Example:
eNMHChot = 0.025 g/mi

(2) You may determine weighted composite NMOG for FTP testing based on the weighted composite NMHC emission rate and the volume percent of ethanol in the fuel using the following equation:

            Eq. 1066.665-3
Where:
eNMOGcomp = weighted composite mass emission rate of NMOG.
eNMHCcomp = weighted composite mass emission rate of NMHC, calculated using ρNMHC-liq.
VPEtOH = volume percentage of ethanol in the test fuel.  Use good engineering judgment to determine this value either as specified in 40 CFR 1065.710 or based on blending volumes, taking into account any denaturant.

Example:
eNMHCcomp = 0.025 g/mi
VPEtOH = 15.1 %

(3) You may determine NMOG for the complete FTP cold-start test interval for use in fuel economy and CREE calculations based on the NMHC emission rate for the test interval and the volume percent of ethanol in the fuel using the following equation:

            Eq. 1066.665-4
Where:
eNMOG-FTPct = mass emission rate of NMOG over the FTP cold start test interval.
eNMHC-FTPct = mass emission rate of NMHC over the FTP cold-start test interval, calculated using ρNMHC-liq.
VPEtOH = volume percentage of ethanol in the test fuel.

Example:
eNMHC-FTPct = 0.052 g/mi
VPEtOH = 15.1 %

(4) You may determine NMOG for the FTP stabilized test interval for either the cold-start or hot-start test for use in fuel economy and CREE calculations based on the NMHC emission rate for the test interval and the volume percent of ethanol in the fuel using the following equation

            Eq. 1066.665-5
Where:
eNMOG-FTPcs-hs = mass emission rate of NMOG over the FTP stabilized test interval.
eNMHC-FTPcs-hs = mass emission rate of NMHC over the FTP stabilized test interval, calculated using ρNMHC-liq.
VPEtOH = volume percentage of ethanol in the test fuel.
(5) You may determine NMOG for the complete FTP hot-start test interval for use in fuel economy and CREE calculations based on the NMHC emission rate for the test interval and the volume percent of ethanol in the fuel using the following equation:

            Eq. 1066.665-6
Where:
eNMOG-FTPht = mass emission rate of NMOG over the FTP hot-start test interval.
eNMHC-FTPht = mass emission rate of NMHC over the FTP hot-start test interval, calculated using ρNMHC-liq.
VPEtOH = volume percentage of ethanol in the test fuel.
(d) You may take the following additional steps when determining fuel economy and CREE under 40 CFR part 600:
(1) Calculate NMOG by interval using Eq. 1066.665-3 for individual bag measurements from the FTP.
(2) Calculate NMOG for two-bag FTPs using Eq. 1066.665-3 for hybrid-electric vehicles as described in 40 CFR 600.114.
(e) We consider NMOG emission values for diesel-fueled vehicles, CNG-fueled vehicles, and LPG-fueled vehicles to be equivalent to NMHC emission values for all test cycles.
(f) For all fuels not covered by paragraphs (c) and (e) of this section, manufacturers may propose a methodology to calculate NMOG results from measured NMHC emissions.  We will approve adjustments based on comparative testing that demonstrates how to properly represent NMOG based on measured NMHC emissions.

§1066.695 Data requirements.
Record the following information for each test:
(a) Test number.
(b) A brief description of the test vehicle (or other system/device tested).
(c) Date and time of day for each part of the test sequence.
(d) Test results.  Also include a validation of driver accuracy as described in §1066.430(j).
(e) Driver and equipment operators.
(f) Vehicle information as applicable, including identification number, model year, applicable emission standards, vehicle model, vehicle class, carline, test group, durability group, engine family, evaporative/refueling emission family, basic engine description (including displacement, number of cylinders, turbocharger/supercharger used, and catalyst type), fuel system (type of fuel injection and fuel tank capacity and location), engine code, gross vehicle weight rating, equivalent test weight, inertia weight class, actual curb weight at zero miles, actual road load at 50 mph, transmission class and configuration, axle ratio, odometer reading, idle rpm, and drive wheel tire pressure.
(g) Dynamometer identification, inertia weight setting, indicated power absorption setting, and records to verify compliance with the driving distance and cycle-validation criteria as calculated from measured roll or shaft revolutions.
(h) Analyzer bench identification, analyzer ranges, recordings of analyzer output during zero, span, and sample readings.
(i) Associate the following information with the test record: test number, date, vehicle identification, vehicle and equipment operators, and identification of the measurements recorded.
(j) Test cell barometric pressure and humidity.  You may use a central laboratory barometer if the barometric pressure in each test cell is shown to be within +-0.1 % of the barometric pressure at the central barometer location.
(k) Records to verify compliance with the ambient temperature requirements throughout the test procedure and records of fuel temperatures during the running loss test.
(l) [Reserved]
(m) For CVS systems record, dilution factor for each interval of the exhaust test and the following additional information:
(1) CFV and SSV Vmix for each interval of the exhaust test.
(2) PDP. Test measurements required to calculate Vmix for each interval of the exhaust test.
(n) The humidity of the dilution air if you remove H2O from an emission sample before measurement.
(o) Temperature of the dilute exhaust mixture and secondary dilution air (in the case of a double-dilution system) at the inlet to the respective gas meter or flow instrumentation used for particulate sampling.
(p) The maximum gas temperature over the course of the test within 20 cm upstream or downstream of the sample media (e.g., filter).
(q) If applicable, the temperature of the heated FID, the gas in the heated sample line, and the heated filter.
(r) Gas meter or flow measurement instrumentation readings at the start and end of each test interval.
(s) The stabilized pre-test weight and post-test weight of each particulate sample media (e.g., filter).
(t) Continuous temperature and humidity of the ambient air in which the particulate sample media (e.g., filter) are stabilized.
(u) For vehicles fueled by natural gas, the test fuel composition, including all carbon-containing compounds (except CO); e.g. CO2, of the natural gas-fuel used during the test.  Record C1 and C2 compounds individually.  You may record C3 through C5 hydrocarbons together, and you may record C6 and heavier hydrocarbon compounds together.
(v) Additional required records for liquefied petroleum gas-fueled vehicles.  For vehicles fueled by liquefied petroleum gas, the test fuel composition, including all carbon-containing compounds (except CO); e.g. CO2.  Each hydrocarbon compound present, through C4 compounds, shall be individually reported.  C5 and heavier hydrocarbons may be reported as a group.  Record C1 and C4 compounds individually.  You may record C5 and heavier hydrocarbon compounds together.

Subpart H -- Cold-Temperature Test Procedures
§1066.701 Applicability and general provisions.
(a)  The procedures of this part 1066 may be used for testing at any ambient temperature.  Section 1066.710 describes the provisions that apply for testing testing motor vehicles at a nominal temperature of  20 °C (68 °F); these procedures apply for motor vechicles as described in 40 CFR part 86, subpart S, and 40 CFR part 600.  For other vehicles, see the standard-setting part to determine if your vehicle is required to meet emission standards outside the normal (20 to 30) °C (68 to 86 °F) temperature range.
(b) Do not apply the humidity correction factor in §1066.630(a) for cold-temperature testing.

§1066.710 Cold-testing procedures for measuring CO and NMHC emissions and determining fuel economy.
This section describes procedures for measuring carbon monoxide (CO) and nonmethane hydrocarbon (NMHC) emissions and determining fuel economy on a cold day using the FTP driving schedule (see §1066.801).
(a) Follow the exhaust emission measurement procedures specified in §§1066.410 through 1066.430 and §1066.820(d), subject to the following exceptions and additional provisions:
   (1) Measure and control ambient conditions as specified in paragraph (b) of this section.
   (2) Precondition and stabilize the vehicle as specified in paragraphs (c) and (d) of this section.  Ensure that there is no precipitation or dew on the vehicle before the emission test.
   (3) For dynamometers that have independently heated bearings, start the emission test within 20 minutes after the end of dynamometer warm up; for other dynamometers, start the emission test within 10 minutes after the end of dynamometer warm up.
   (5) Analyze samples for NMHC, CO, and CO2.  You do not need to analyze samples for other pollutants.
(b) Maintain ambient conditions as follows instead of following the specifications in subpart E of this part:
   (1) Ambient temperature for emission tests.  Measure and record ambient temperature in the test cell at least once every 60 seconds during the sampling period. The average temperature during the sampling period must be (−7.0 +-1.7) °C.  Instantaneous temperature values may be above −4.0 °C or below −9.0 °C, but not for more than 3 minutes at a time.
   (2) Ambient temperature for preconditioning.  Ambient temperatures must be between (−14.0 and −1.0) °C throughout the preconditioning period.  The average ambient temperature during preconditioning must be (−7.0 +-2.8) °C.  You may precondition vehicles at temperatures above −7.0 °C or with a temperature tolerance greater than that described in this section (or both) if you determine that this will not cause NMHC, CO, or CO2 emissions to decrease; if you modify the temperature specifications for vehicle preconditioning, adjust the procedures described in this section appropriately for your testing.  Use good engineering judgment to demonstrate that you meet the specified temperature tolerances specified in this paragraph (b)(2).
   (3) Ambient humidity.  Maintain humidity low enough to prevent condensation on the dynamometer rolls during testing.
(c) Take the following steps to prepare and precondition vehicles for testing under this section:
   (1) Prepare the vehicle as described in §1066.814(a).
   (2) Fill the fuel tank to approximately 40 % of the manufacturer's nominal fuel tank capacity with the appropriate test fuel for low-temperature testing specified 40 CFR part 1065, subpart H.  If the leftover fuel in the fuel tank before the refueling event does not meet these specifications, drain the fuel tank before refueling.  The temperature of the dispensed test fuel must be at or below 15.5 °C.
   (3) You may start the preconditioning drive once the fuel in the fuel tank reaches (−7.0 °C +-5.6) °C. Precondition the vehicle as follows:
      (i) Push or drive the vehicle onto the dynamometer.
      (ii) Operate the vehicle over one UDDS.  You may perform additional vehicle preconditioning with repeated driving over the UDDS, subject to our advance approval.
      (iii) Turn off the test vehicle and any cooling fans within 5 minutes after completing the preconditioning drive.  Ambient temperature must be between (−12.0 to −1.0) °C in the 5 minutes following the preconditioning drive.
      (iv) Do not manually purge or load the evaporative canister.
(d) Soak the vehicle for (12 to 36) hours to stabilize it at test temperatures before starting the emission test as described in this paragraph (d).  If you move a stabilized vehicle through a warm area when transporting it to the dynamometer for testing, you must restabilize the vehicle by holding it at an ambient temperature within the range specified in paragraph (b)(1) of this section for at least six times as long as the vehicle was exposed to warmer temperatures.  Use one of the following methods to reach a stabilized condition:
   (1) Cold storage.  Measure and record ambient temperature in the test cell at least once every 60 seconds during the soak period; use these measured values to calculate an hourly average temperature.  Each hourly average temperature must be (−7.0 °C +-2.8) °C. Instantaneous ambient temperatures during the soak period may be above −1.0 °C or below −12.0, but not for more than 3 minutes at a time.
   (2) Forced-cooling or warming.  Position fans to blow temperature-controlled air onto the vehicle to stabilize the vehicle at the specified temperatures for emission testing.  Position fans to target the vehicle's drive train, engine block, and radiator rather than the oil pan.  You may not place fans under the vehicle.  You may consider the vehicle to be stabilized at the test temperature when the bulk oil temperature reaches (−7 +-1.7) °C; measure oil temperature at one or more points away from the side or bottom surfaces of the oil pan.  Each oil temperature measurement must be within the specified range before stabilization is complete.  Once the vehicle reaches this stabilized condition, hold the vehicle within the stabilized temperature range for at least one hour before starting the emission test.  During this time, keep the ambient temperature within the range specified in paragraph (b)(1) of this section.

Subpart I -- Exhaust Emission Test Procedures for Motor Vehicles
§1066.801 Applicability and general provisions.
This subpart I specifies how to apply the test procedures of this part for motor vehicles at or below 14,000 pounds GVWR, including light-duty vehicles, light-duty trucks, and heavy-duty vehicles at or below 14,000 pounds GVWR that are subject to chassis testing for exhaust emissions.   For these vehicles, references in this part 1066 to the standard-setting part include this subpart I.
(a) Use the procedures detailed in this subpart to measure vehicle emissions over a specified drive schedule in conjunction with subpart E of this part.  Where the procedures of subpart E of this part differ from this subpart I, the provisions in this subpart I take precedence.
(b) Collect samples of every pollutant for which an emission standard applies, unless specified otherwise.
(c) This subpart covers the following test procedures:
(1) The Federal Test Procedure (FTP), which includes the general driving cycle.  This procedure is also used for measuring evaporative emissions.  This may be called the conventional test since it was adopted with the earliest emission standards.
(i) The FTP consists of one Urban Dynamometer Driving Schedule (UDDS) as specified in paragraph (a) of Appendix I of 40 CFR part 86, followed by a 10-minute soak with the engine off and repeat driving through the first 505 seconds of the UDDS.  Note that the UDDS represents about 7.5 miles of driving in an urban area.  Engine startup (with all accessories turned off), operation over the initial UDDS, and engine shutdown make a complete cold-start test.  The hot-start test consists of the first 505 seconds of the UDDS following the 10-minute soak and a hot-running portion of the UDDS after the first 505 seconds.  The first 505 seconds of the UDDS is considered the transient portion; the remainder of the UDDS is considered the stabilized (or hot-stabilized) portion.  The hot-stabilized portion for the hot-start test is generally measured during the cold-start test; however, in certain cases, the hot-start test may involve a second full UDDS following the 10-minute soak, rather than repeating only the first 505 seconds.  See §§1066.820 and 1066.822.
(ii) Evaporative emission testing includes a preconditioning drive with the UDDS and a full FTP cycle, including exhaust measurement, followed by evaporative emission measurements.  In the three-day diurnal test sequence, the exhaust test is followed by a running loss test consisting of a UDDS, then two New York City Cycles as specified in paragraph (f) of Appendix I of 40 CFR part 86, followed by another UDDS; see 40 CFR 86.134-96.  Note that the New York City Cycle represents about 1.7 miles of driving in a city center.  The running loss test is followed by a high-temperature hot soak test as described in 40 CFR 86.138-96 and a three-day diurnal emission test as described in 40 CFR 86.133-96.  In the two-day diurnal test sequence, the exhaust test is followed by a low-temperature hot soak test as described in 40 CFR 86.138-96(k) and a two-day diurnal emission test as described in 40 CFR 86.133-96(p).
(iii) Refueling emission tests for vehicles that rely on integrated control of diurnal and refueling emissions includes vehicle operation over the full FTP test cycle corresponding to the three-day diurnal test sequence to precondition and purge the evaporative canister.  For non-integrated systems, there is a preconditioning drive over the UDDS and a refueling event, followed by repeated UDDS driving purge the evaporative canister.  The refueling emission test procedures are described in 40 CFR 86.150 through 86.157.
(2) The Supplemental Federal Test Procedure (SFTP) measures the emission effects from aggressive driving and operation with the vehicle's air conditioner.   The SFTP is based on a composite of three different test elements.  In addition to the FTP, vehicles generally operate over the US06 and SC03 driving schedules as specified in paragraphs (g) and (h) of Appendix I of 40 CFR part 86, respectively.  In the case of heavy-duty vehicles above 10,000 pounds GVWR and at or below 14,000 pounds GVWR, SFTP testing involves additional driving over the LA-92 driving schedule specified in paragraph (c) of 40 CFR part 86, Appendix I, instead of the US06 driving schedule.  Note that the US06 driving schedule represents about 8.0 miles of relatively aggressive driving; the SC03 driving schedule represents about 3.6 miles of urban driving with the air conditioner operating; and the LA-92 driving schedule represents about 9.8 miles of relatively aggressive driving for commercial trucks.  See §§1066.820 and 1066.822.
(3) The Highway Fuel Economy Test (HFET).  The HFET is specified in Appendix I of 40 CFR part 600.  Note that the HFET represents about 10.2 miles of rural and freeway driving with an average speed of 48.6 mph and a maximum speed of 60.0 mph.  See §1066.839.
(4) Cold-temperature testing.  Cold-temperature standards apply for CO and NMHC emissions when vehicles operate over the FTP at a nominal temperature of -7 °C.  See 40 CFR part 86, subpart C.
(5) Emission measurement to determine air conditioning credits for greenhouse gas standards.  In this optional procedure, manufacturers operate vehicles over repeat runs of the AC17 test sequence to allow for calculating credits as part of demonstrating compliance with CO2 emission standards. The AC17 test sequence consists of a UDDS preconditioning drive, followed by emission measurements over the SC03 and HFET driving schedules.  See §1066.835.
(d)  The following provisions apply for all testing:
(1) Ambient temperatures encountered by the test vehicle must be (20 to 30) °C, unless otherwise specified.  Where ambient temperature specifications apply before or between test measurements, the vehicle may be exposed to temperatures outside of the specified range for up to 10 minutes to account for vehicle transport or other actions to prepare for testing.  The temperatures monitored during testing must be representative of those experienced by the test vehicle.  For example, do not measure ambient temperatures near a heat source.
(2) Do not operate or store the vehicle at an incline if good engineering judgment indicates that it would affect emissions.
(3) If a test is void after collecting emission data from previous test segments, the test may be repeated to collect only those data points needed to complete emission measurements.  You may combine emission measurements from different test runs to demonstrate compliance with emission standards.
(4) Prepare vehicles for testing as described in §1066.814.
(e) The following figure illustrates the FTP test sequence for measuring exhaust and evaporative emissions:
Figure 1 of §1066.801 - FTP test sequence.

§1066.810 Road load power, test weight, and inertia weight class determination.
(a)  Simulate a vehicle's test weight on the dynamometer using the appropriate equivalent test weight shown in Table 1 of this section.  Equivalent test weights are established according to each vehicle's test weight basis, as described in paragraph (b) of this section.  Table 1 also specifies the inertia weight class corresponding to each equivalent test weight; the inertia weight class allows for grouping vehicles with a range of equivalent test weights.  Table 1 follows:

Table 1 of §1066.810 - Equivalent test weights (pounds)
Test weight
basis
Equivalent test weight
Inertia weight class
Up to 1062
1000
1000
1063 to 1187
1125
1000
1188 to 1312
1250
1250
1313 to 1437
1375
1250
1438 to 1562
1500
1500
1563 to 1687
1625
1500
1688 to 1812
1750
1750
1813 to 1937
1875
1750
1938 to 2062
2000
2000
2063 to 2187
2125
2000
2188 to 2312
2250
2250
2313 to 2437
2375
2250
2438 to 2562
2500
2500
2563 to 2687
2625
2500
2688 to 2812
2750
2750
2813 to 2937
2875
2750
2938 to 3062
3000
3000
3063 to 3187
3125
3000
3188 to 3312
3250
3000
3313 to 3437
3375
3500
3438 to 3562
3500
3500
3563 to 3687
3625
3500
3688 to 3812
3750
3500
3813 to 3937
3875
4000
3938 to 4125
4000
4000
4126 to 4375
4250
4000
4376 to 4625
4500
4500
4626 to 4875
4750
4500
4876 to 5125
5000
5000
5126 to 5375
5250
5000
5376 to 5750
5500
5500
5751 to 6250
6000
6000
6251 to 6750
6500
6500
6751 to 7250
7000
7000
7251 to 7750
7500
7500
7751 to 8250
8000
8000
8251 to 8750
8500
8500
8751 to 9250
9000
9000
9251 to 9750
9500
9500
9751 to 10250
10000
10000
10251 to 10750
10500
10500
10751 to 11250
11000
11000
11251 to 11750
11500
11500
11751 to 12250
12000
12000
12251 to 12750
12500
12500
12751 to 13250
13000
13000
13251 to 13750
13500
13500
13751 to 14000
14000
14000

(b) The test weight basis for non-MDPV heavy-duty vehicles is "adjusted loaded vehicle weight".  For all other vehicles, the test weight basis for establishing equivalent test weight is "loaded vehicle weight".  These load terms are defined in 40 CFR 86.1803.
(c) For FTP and SFTP testing, determine road load forces for each test vehicle at speeds between 10 and 70 miles per hour.  The road load force must represent vehicle operation on a smooth, level road with no wind or calm winds, no precipitation, an ambient temperature of approximately 20 °C, and atmospheric pressure of 98.21 kPa.  You may extrapolate road load force for speeds below 10 mph.

§1066.814 Vehicle preparation.
(a) Include additional fittings and adapters, as required, to accommodate a fuel drain at the lowest point possible in the tank(s) as installed on the vehicle.
(b) For preconditioning that involves loading an evaporative emission canister with butane, provide valving or other means as necessary to allow purging and loading of the canister.
(c) For vehicles to be tested for running loss emissions (40 CFR 86.134), prepare the fuel tank for measuring temperature and pressure as specified in 40 CFR 86.107 - 98(e) and (f) and 40 CFR 86.134.  Vapor temperature measurement is optional during the running loss test.
(d) For vehicles to be tested for running loss emissions, prepare the exhaust system by sealing or plugging all detectable sources of exhaust gas leaks.  Inspect or test the exhaust system to ensure that there are no leaks that would cause exhaust hydrocarbon emissions to be detected as running losses.
(e) The following provisions apply for preconditioning steps to reduce nonfuel emissions to normal vehicle background levels for vehicles subject to Tier 3 evaporative emission standards under 40 CFR 86.1813:
(1) You must notify us in advance if you plan to perform such preconditioning.  This notice must include a detailed description of the intended procedures and any measurements or thresholds for determining when stabilization is complete.  You need not repeat this notification for additional vehicle testing in the same or later model years as long as your preconditioning practice conforms to these procedures.
(2) You may precondition a vehicle as described in paragraph (e)(1) of this section only within 12 months after the vehicle's original date of manufacture, except that you may remove the spare tire for any testing.

§1066.820 Exhaust emission test procedures for FTP testing.
(a) General.  The FTP exhaust emission test sequence consists of a cold-start test and a hot-start test as described in §1066.801.
(b) PM sampling options.  Collect PM using any of the procedures specified in paragraphs (b)(1) through (5) of this section and use the corresponding equation in §1066.822 to calculate FTP composite emissions.  Testing must meet the requirements related to filter face velocity as described in 40 CFR 1065.170(c)(1)(vi), except as specified in paragraphs (b)(4) and (5) of this section.   For procedures involving flow weighting, set the filter face velocity to a weighting target of 1.0 to meet the requirements of 40 CFR 1065.170(c)(1)(vi).  Allow filter face velocity to decrease as a percentage of the weighting factor if the weighting factor is less than 1.0.  Use the appropriate equations in §1066.620 to show that you meet the dilution factor requirements of §1066.110(b)(2)(iii)(B).
(1) You may collect a separate PM sample for transient and stabilized portions of the cold-start UDDS and the hot-start UDDS.  This may either be done by sampling with 3 bags or 4 bags.  You may omit the stabilized portion of the hot-start test (bag 4) and use the stabilized portion of the cold-start test (bag 2) in its place.
(2) You may collect PM on one filter over the cold-start UDDS and on a separate filter over the hot-start UDDS.
(3) You may collect PM on one filter over the cold-start UDDS (bag 1 and bag 2) and on a separate filter over the 867 seconds of the stabilized portion of the cold-start UDDS and the first 505 seconds of the hot-start UDDS (bag 2 and bag 3).  Note that this option involves duplicate measurements during the stabilized portion of the cold-start UDDS.
(4) You may collect PM on a single filter over the cold-start UDDS and the first 505 seconds of the hot-start UDDS.  If you use this method, adjust your sampling system flow rate to weight the filter face velocity over the three intervals of the FTP based on weighting targets of 0.43 for bag 1, 1.0 for bag 2, and 0.57 for bag 3.
(5) You may collect PM on a single filter over the cold-start UDDS and the full hot-start UDDS.  If you use this method, adjust your sampling system flow rate to weight the filter face velocity based on weighting targets of 0.75 for the cold-start UDDS and 1.0 for the hot-start UDDS.
(c) Gaseous sampling options.  Collect gaseous samples using any of the following procedures:
(1) You may collect a single sample for a full UDDS (cold-start or hot-start).
(2) You may sample emissions separately for transient and stabilized portions of any UDDS.
(3) You may omit the stabilized portion of the hot-start test (bag 4) and use the stabilized portion of the cold-start test (bag 2) in its place.
(4) You may apply the provisions of paragraph (b) of this section for any gaseous batch measurement, consistent with good engineering judgment.
(d) Test sequence.  Follow the exhaust emission measurement procedures specified in §§1066.410 through 1066.430, subject to the following exceptions and additional provisions:
(1) Take the following steps for the cold-start test:
(i) Precondition the vehicle as described in 40 CFR 86.132.  Initiate the cold-start test following the 12 to 36 hour soak period.
(ii) Start sampling and recording simultaneously with starting the vehicle.  Fifteen seconds after the engine starts, place the transmission in gear.  Twenty seconds after the engine starts, begin the initial vehicle acceleration of the driving schedule.
(iii) At the end of the deceleration scheduled to occur 505 seconds into the cold-start UDDS, simultaneously switch all the sample flows from the cold-start transient interval to the stabilized interval, stopping all cold-start transient interval sampling and recording, including background sampling.  Reset integrating devices for the stabilized interval and indicate the end of the cold-start interval in the recorded data.  Operate the vehicle over the remainder of the UDDS.  Turn the engine off 2 seconds after the end of the last deceleration in the stabilized interval (1,369 seconds after the start of the driving schedule).
(iv) Five seconds after the engine stops running, stop all stabilized interval sampling and recording, including background sampling.  Stop any integrating devices for the stabilized interval and indicate the end of the stabilized interval in the recorded data.  Note that the 5 second delay is intended to account for sampling system transport.
(2) Take the following steps for the hot-start test:
(i) Initiate the hot-start test (9 to 11) minutes after the end of the sample period for the cold-start UDDS.
(ii) Repeat the steps in paragraph (d)(1)(ii) of this section.  Operate the vehicle over the first 505 seconds of the UDDS.  At the end of the deceleration scheduled to occur 505 seconds into the hot-start UDDS, turn off the engine and simultaneously stop all hot-start sampling and recording, including background sampling, and any integrating devices.
(iii) For tests that do not include bag 4 operation, turn the engine off.  To include bag 4 measurement, operate the vehicles over the remainder of the UDDS and conclude the testing as described in paragraphs (d)(1)(iii) and (iv) of this section.
(3) This completes the procedure for measuring FTP exhaust emissions.  See 40 CFR part 86, subpart B, and §1066.801 for continuing to evaporative or refueling tests.

§1066.822 Composite calculations for FTP exhaust emissions.
(a) Determine the mass of exhaust emissions of each pollutant for each FTP test interval as described in §1066.610.
(b) Calculate the final composite gaseous test results as a mass-weighted value, e[emission]-FTPcomp, in grams per mile using the following equation:

                  	Eq. 1066.822-1

Where:
mc = the combined mass emissions determined from the cold-start UDDS test interval (generally known as bag 1 and bag 2), in grams.
Dct = the measured driving distance from the transient portion of the cold-start test (bag 1), in miles.
Dcs = the measured driving distance from the stabilized portion of the cold-start test (bag 2), in miles.
mh = the combined mass emissions determined from the hot-start UDDS test interval in grams.  This is the hot-stabilized portion from either the first or second UDDS (bag 2, unless you measure bag 4), in addition to the hot transient portion (bag 3).
Dht = the measured driving distance from the transient portion of the hot-start test (bag 3), in miles.
Dhs = the measured driving distance from the stabilized portion of the hot-start test (bag 4), in miles.  Set Dhs = Dcs for testing where the hot-stabilized portion of the UDDS is not run.
(c) Calculate the final composite PM test results as a mass-weighted value, ePM-FTPcomp, in grams per mile as follows:
(1) Use the following equation for PM measured as described in §1066.820(b)(1), (2), or (3):

                  	Eq. 1066.822-2
Where:
mPM-cUDDS = the combined PM mass emissions determined from the cold-start UDDS test interval (bag 1 and bag 2), in grams, as calculated using Eq. 1066.610-2.
mPM-hUDDS = the combined PM mass emissions determined from the hot-start UDDS test interval (bag 3 and bag 4), in grams, as calculated using Eq. 1066.610-2.  This is the hot-stabilized portion from either the first or second UDDS (bag 2, unless you measure bag 4), in addition to the hot transient portion (bag 3).
(2) Use the following equation for PM measured as described in §1066.820(b)(4):

                  	Eq. 1066.822-3
Where:
mPM = the combined PM mass emissions determined from the cold-start UDDS test interval and the first 505 seconds of the hot-start UDDS test interval (bag 1, bag 2, and bag 3), in grams, as calculated using Eq. 1066.610-3.
(3) Use the following equation for PM measured as described in §1066.820(b)(5):

                  	Eq. 1066.822-4
Where:
mPM = the combined PM mass emissions determined from the cold-start UDDS test interval and the hot-start UDDS test interval (bag 1, bag 2, bag 3, and bag 4), in grams, as calculated using Eq. 1066.610-4.

§1066.830 Supplemental Federal Test Procedures; overview.
Sections 1066.831 and 1066.832 describe the detailed procedures for the Supplemental Federal Test Procedure (SFTP). This testing applies for all vehicles subject to the SFTP standards in 40 CFR part 86, subpart S. The SFTP test procedure consists of FTP testing and two additional test elements -- a sequence of vehicle operation with more aggressive driving and a sequence of vehicle operation that accounts for the impact of the vehicle's air conditioner.
(a) The SFTP standard applies as a composite representing the three test elements.  The emission results from the aggressive driving test element (§1066.831), the air conditioning test element (§1066.832), and the FTP test element (§1066. 820) are analyzed according to the calculation methodology and compared to the applicable SFTP emission standards as described in 40 CFR part 86, subpart S.
(b) The test elements of the SFTP may be run in any sequence that includes the specified preconditioning steps.

§1066.831 Exhaust emission test procedures for aggressive driving.
(a) This section describes how to test using the US06 or LA-92 driving schedule.  The US06 driving schedule can be divided into two test intervals -- the US06 City cycle comprises the combined portions of the cycle from 1 to 130 seconds and from 495 to 596 seconds, and the US06 Highway cycle comprises the portion of the cycle between 130 and 495 seconds.  See §1066.801 for further information on the driving schedules.
(b) Take the following steps to precondition vehicles for testing under this section:
(1) Drain and refill the vehicle's fuel tank(s) in any of the following cases:
(i) For aggressive-driving tests that do not follow FTP or HFET testing.
(ii) For a test element that starts more than 72 hours after the most recent FTP or HFET measurement (with or without evaporative emission measurements).
(iii) For testing in which the test vehicle has not remained in an area where ambient temperatures were within the range specified for testing since the previous FTP or HFET.
(2) Keep ambient temperatures within the ranges specified for test measurements throughout the preconditioning sequence.
(3) Warm up the vehicle to a stabilized condition as follows:
(i) Push or drive the vehicle onto the dynamometer.
(ii) Operate the vehicle one time over one of the driving schedules specified in this paragraph (b)(3)(iii).  You may ask us to use a particular preconditioning driving schedule if that is related to fuel effects on adaptive memory systems.  For our testing, we will generally operate the vehicle over the same preconditioning cycle that will be used for testing in this section.  You may exercise your sampling equipment, but you may not determine emissions results during preconditioning.  Choose from the following driving schedules:
(A)  The first 505 seconds of the UDDS (bag 1)
(B) The last 866 seconds of the UDDS (bag 2).
(C) The HFET driving schedule.
(D) US06 driving schedule or, for heavy-duty vehicles above 10,000 pounds GVWR, just the highway portion of the US06 driving schedule.
(E) The SC03 driving schedule.
(F) The LA-92 driving schedule.
(4) Allow the vehicle to idle for (1 to 2) minutes.  This leads directly into the test measurements described in paragraph (c) of this section.
(c) For testing involving the full US06 driving schedule, you may collect emissions from separate city and highway test intervals (see 40 CFR part 600), or you may collect emissions over the full US06 driving schedule as a single test interval.  Take the following steps for to measure emissions over separate city and highway test intervals:
(1) At 130 seconds, simultaneously stop all US06 City, and start all US06 Highway sampling, recording, and integrating (including background sampling).  At 136 seconds (before the acceleration), record the measured dynamometer roll revolutions.
(2) At 495 seconds, simultaneously stop all US06 Highway, and start all US06 City sampling, recording, and integrating (including background sampling). At 500 seconds (before the acceleration), record the measured dynamometer roll revolutions.
(3) Except as specified in paragraph (c)(4) of this section, treat the emissions from the first and second portions of the US06 City test interval as a single sample.
(4) If you collect gaseous emissions over separate city and highway test intervals, you may still collect PM over the full US06 driving schedule as a single test interval.  If you do this, calculate a composite dilution factor based on city and highway emissions using Eq. 1066.620-4 to show that you meet the dilution factor requirements of §1066.110(b)(2)(iii)(B).
(d) For diesel-fueled vehicles, measure THC emissions on a continuous basis as described in 40 CFR part 1065.  For separate measurement of the city and highway test intervals as described in paragraph (c) of this section, perform separate calculations for each portion of the test cycle.
(f) Follow the exhaust emission measurement procedures specified in §§1066.410 through 1066.430, subject to the following exceptions and additional provisions:
(1) Following the preconditioning specified in §1066.830, place the vehicle in gear and simultaneously start sampling and recording.  Begin the first acceleration 5 seconds after placing the vehicle in gear.
(2) Operate the vehicle over the full US06 driving schedule, except as follows:
(i) For heavy-duty vehicles above 10,000 pounds GVWR, operate the vehicle over the LA-92 driving schedule.
(ii) Heavy-duty vehicles at or below 10,000 pounds GVWR may be certified using only the highway portion of the US06 driving schedule.  See 40 CFR 86.1816.
(3) Turn the engine off 2 seconds before the end of the driving schedule.  Five seconds after the engine stops running, stop all sampling and recording, including background sampling.  Stop any integrating devices and indicate the end of the test cycle in the recorded data.
(4) Correct calculated NOx emissions as described in §1066.630(a)(1).

§1066.832 Exhaust emission test procedure for SC03 emissions.
This section describes how to test using the SC03  driving schedule (see §1066.801).   This procedure is designed to determine gaseous exhaust emissions while simulating an urban trip on a hot summer day.  The provisions of 40 CFR part 86 and 40 CFR part 600 waive SC03 testing for some vehicles; in those cases, calculate SFTP composite emissions by adjusting the weighting calculation as specified in 40 CFR part 86, subpart S.
(a) Keep the vehicle in an environment meeting the conditions described in paragraph (e) of this section throughout the preconditioning sequence.
(b) Warm up the vehicle to a stabilized condition as follows:
(1) Push or drive the test vehicle onto the dynamometer.
(2) Operate the test vehicle one time over the first 505 seconds of the UDDS (bag 1), the last 867 seconds of the UDDS (bag 2), or the SC03 driving schedule.  If the air conditioning test sequence starts more than 2 hours after a different exhaust emission test, you may instead operate the vehicle one time over the full UDDS.
(3) Following the preconditioning drive, turn off the test vehicle and the vehicle cooling fan(s) and allow the vehicle to soak for (9 to 11) minutes.
(c) Follow the exhaust emission measurement procedures specified in §§1066.410 through 1066.430, subject to the following exceptions and additional provisions:
(1) Close the vehicle's windows before testing.
(2) The test cell and equipment must meet the specifications in paragraph (d) of this section.  Measure and control ambient conditions as specified in paragraph (e) of this section.
(3) Set the vehicle's air conditioning controls by selecting A/C mode and "maximum", setting airflow to "recirculate" (if so equipped), selecting the highest fan setting, and turning the A/C temperature to full cool (or 72 °F for automatic systems).  Turn the control to the "on" position before testing so the air conditioning system is active whenever the engine is running.
(4) Place the vehicle in gear 15 seconds after engine starting.  Follow the SC03 driving schedule.
(5) Turn the engine off 2 seconds before the end of the driving schedule.  Five seconds after the engine stops running, stop all sampling and recording, including background sampling.  Stop any integrating devices any indicate the end of the test cycle in the recorded data.  Note that the 5 second delay is intended to account for sampling system transport.
(6) Correct calculated NOx emissions as described in §1066.630(a)(2).
(d) The following requirement apply for the test cell and cooling fan configuration:
(1) Minimum test cell size. The test cell must be at least 20 feet wide, 40 feet long, and 10 feet high, unless we approve the use of a smaller test cell.  We will approve this only if you demonstrate that the smaller test cell is capable of meeting all the requirements of this section.
(2) Vehicle frontal air flow.  Verify that the fan configuration meets the requirements of §1066.105(c)(3) before each test.
(e) Maintain ambient conditions as follows:
(1) Ambient temperature. Measure and record ambient temperature in the test cell at least once every 30 seconds during the sampling period.  Control ambient temperature during emission sampling to 35.0 +-3.0 °C throughout the test and  (33.6 to 36.4) °C on average.
(2) Ambient humidity. Measure and record ambient humidity in the test cell at least once every 30 seconds during the sampling period.  Control ambient humidity during emission sampling as described in §1066.425(d).
(3) Conditions before and after testing.  Use good engineering judgment to demonstrate that you meet the specified instantaneous temperature and humidity tolerances in paragraphs (e)(1) and (2) of this section at all times before and between emission measurements.
(4) Solar heat load. Simulate solar heating as follows:
(i) You may use a metal halide lamp, a sodium lamp, or a quartz halogen lamp with dichroic mirrors as a radiant energy emitter.  We may also approve the use of a different type of radiant energy emitter if you demonstrate that it meets the requirements of this section.
(ii) We recommend achieving radiant heating with spectral distribution characteristics as described in the following table:
Table 1 of §1066.832 - Recommended Spectral Distribution
Band width (nm)
Percent of total spectrum

Lower limit (%)
Upper limit (%)
<320[a]
 --
0
320 - 400
0
7
400 - 780
45
55
>780
35
53
[a]Note that you may need to filter the UV region between 280 and 320 nm.

(iii) Determine radiant energy intensity experienced by the vehicle as the average value between two measurements along the vehicle's centerline, one at the base of the windshield and the other at the bottom of the rear window (or equivalent location for vehicles without a rear window).  This value must be 850 +-45 W/m[2].  Instruments for measuring radiant energy intensity must meet the following minimum specifications:
(A) Sensitivity of 9 microvolts per W/m[2].
(B) Response time of 5 seconds.  For purposes of this requirement, "response time" means the time for the instrument to reach 95 percent of its equilibrium response after a step change in radiant intensity.
(C) Linearity of +- 0.5 %.
(D) Cosine response error of no more than +- 1 % for 0 - 70 degree zenith angles.  The cosine response error is the percentage difference between the intensity measured at a given angle and the intensity predicted from the zero-degree intensity and the cosine of the incident angle.
(iv) Check the uniformity of radiant energy intensity at least every 500 hours of emitter usage or every 6 months, whichever is sooner, and after any major modifications affecting the solar simulation.  Determine uniformity by measuring radiant energy intensity as described in paragraph (e)(4)(iii) of this section at each point of a 0.5 m grid over the vehicle's full footprint, including the edges of the footprint, at an elevation 1 m above the floor.  Measured values of radiant energy intensity must be between (722 and 978) W/m[2] at all points.

§1066.835 AC17 air conditioning efficiency test procedure.
(a) Overview.  This section describes a voluntary procedure for measuring the net impact of air conditioner operation on CO2 emissions.  See 40 CFR 86.1868 for provisions describing how to use these procedures to calculate credits and otherwise comply with emission standards.
(b) Test cell.  Operate the vehicle in a test cell meeting the specifications described in §86.832(d).  You may add airflow up to at a maximum of 4 miles per hour during engine idling and when the engine is off if that is needed to meet ambient temperature or humidity requirements.
(c) Ambient conditions.  Measure and control ambient conditions as specified in §86.832(e), except that you must control ambient temperature during emission sampling to 25.0 +-3.0 °C throughout the test and (23.6 to 26.4) °C on average.  Note that solar heating is disabled for certain test intervals as described in this section.