a certificate of conformity if you do any of the following:
    (1) Refuse to comply with any testing or reporting requirements in
this part.
    (2) Submit false or incomplete information. This includes doing
anything after submitting an application that causes submitted
information to be false or incomplete.
    (3) Cause any test data to become inaccurate.
    (4) Deny us from completing authorized activities (see 40 CFR
1068.20). This includes a failure to provide reasonable assistance.
    (5) Produce engines for importation into the United States at a
location where local law prohibits us from carrying out authorized
activities.

    (6) Fail to supply requested information or amend an application to
include all engines being produced.
    (7) Take any action that otherwise circumvents the intent of the
Act or this part.
    (d) We may void a certificate of conformity if you fail to keep
records, send reports, or give us information as required under this
part or the Act. Note that these are also violations of 40 CFR
1068.101(a)(2).
    (e) We may void a certificate of conformity if we find that you
intentionally submitted false or incomplete information. This includes
doing anything after submitting an application that causes submitted
information to be false or incomplete after submission.
    (f) If we deny an application or suspend, revoke, or void a
certificate, you may ask for a hearing (see Sec.  1036.820).

Subpart D--Testing Production Engines and Hybrid Powertrains

Sec.  1036.301  Measurements related to GEM inputs in a selective
enforcement audit.

    (a) Selective enforcement audits apply for engines as specified in
40 CFR part 1068, subpart E. This section describes how this applies
uniquely in certain circumstances.
    (b) Selective enforcement audit provisions apply with respect to
your fuel maps as follows:
    (1) A selective enforcement audit for an engine with respect to
fuel maps would consist of performing measurements with production
engines to determine fuel-consumption rates as declared for GEM
simulations, and running GEM for the vehicle configurations specified
in paragraph (b)(2) of this section based on those measured values. The
engine is considered passing for a given configuration if the new
modeled emission result for each applicable duty cycle is at or below
the modeled emission result corresponding to the declared GEM inputs.
The engine is considered failing if we determine that its fuel map
result is above the modeled emission result corresponding to the result
using the manufacturer-declared fuel maps, as specified in Sec.
1036.235(c)(5).
    (2) If the audit includes fuel-map testing in conjunction with
engine testing relative to exhaust emission standards, the fuel-map
simulations for the whole set of vehicles and duty cycles counts as a
single test result for purposes of evaluating whether the engine family
meets the pass-fail criteria under 40 CFR 1068.420.
    (c) If your certification includes powertrain testing as specified
in 40 CFR 1036.630, these selective enforcement audit provisions apply
with respect to powertrain test results as specified in 40 CFR part
1037, subpart D, and 40 CFR 1037.550. We may allow manufacturers to
instead perform the engine-based testing to simulate the powertrain
test as specified in 40 CFR 1037.551.
    (d) We may suspend or revoke certificates for any appropriate
configurations within one or more engine families based on the outcome
of a selective enforcement audit.

Subpart E--In-Use Testing

Sec.  1036.401  Testing requirements for in-use engines.

    (a) We may perform in-use testing of any engine family subject to
the standards of this part, consistent with the Clean Air Act and the
provisions of Sec.  1036.235.
    (b) This subpart describes a manufacturer-run field-testing program
that applies for engines subject to compression-ignition standards
under Sec.  1036.104. Note that the testing requirements of 40 CFR part
86, subpart T, continue to apply for engines subject to exhaust
emission standards under 40 CFR part 86.
    (c) In-use test procedures for engines subject to spark-ignition
standards apply as described in Sec.  1036.530. We won't require
routine manufacturer-run field testing for Spark-ignition HDE, but the
procedures of this subpart describe how to use field-testing procedures
to measure emissions from engines installed in vehicles. Use good
engineering judgment to apply the measurement procedures for fuels
other than gasoline.
    (d) We may void your certificate of conformity for an engine family
if you do not meet your obligations under this subpart. We may also
void individual tests and require you to retest those vehicles or take
other appropriate measures in instances where you have not performed
the testing in accordance with the requirements described in this
subpart.

Sec.  1036.405  Overview of the manufacturer-run field-testing program.

    (a) You must test in-use engines from the families we select. We
may select the following number of engine families for testing, except
as specified in paragraph (b) of this section:
    (1) We may select up to 25 percent of your engine families in any
calendar year, calculated by dividing the number of engine families you
certified in the model year corresponding to the calendar year by four
and rounding to the nearest whole number. We will consider only engine
families with annual nationwide production volumes above 1,500 units in
calculating the number of engine families subject to testing each
calendar year under the annual 25 percent engine family limit. If you
have only three or fewer families that each exceed an annual nationwide
production volume of 1,500 units, we may select one engine family per
calendar year for testing.
    (2) Over any four-year period, we will not select more than the
average number of engine families that you have certified over that
four-year period (the model year when the selection is made and the
preceding three model years), based on rounding the average value to
the nearest whole number.
    (3) We will not select engine families for testing under this
subpart from a given model year if your total nationwide production
volume was less than 100 engines.
    (b) If there is clear evidence of a nonconformity with regard to an
engine family, we may select that engine family without counting it as
a selected engine family under paragraph (a) of this section. For
example, there may be clear evidence of a nonconformity if you certify
an engine family using carryover data after reaching a fail decision
under this subpart in an earlier model year without modifying the
engine to remedy the problem.
    (c) We may select any individual engine family for testing,
regardless of its production volume except as described in paragraph
(a)(3) of this section, as long as we do not select more than the
number of engine families described in paragraph (a) of this section.
We may select an engine family from model year 2027 or any later model
year.
    (d) You must complete all the required testing and reporting under
this subpart (for all ten test engines, if applicable), within 18
months after we receive your proposed plan for recruiting, screening,
and selecting vehicles. We will typically select engine families for
testing and notify you in writing by June 30 of the applicable calendar
year. If you request it, we may allow additional time to send us this
information.
    (e) If you make a good-faith effort to access enough test vehicles
to complete the testing requirements under this subpart for an engine
family, but are unable to do so, you must ask us either to modify the
testing requirements for the selected engine family or to select a
different engine family.

    (f) We may select an engine family for repeat testing in a later
calendar year. Such a selection for repeat testing would count as an
additional engine family for that year under paragraph (a) of this
section.

Sec.  1036.410  Selecting and screening vehicles and engines for
testing.

    (a) Send us your proposed plan for recruiting, screening, and
selecting vehicles. Identify the types of vehicles, location, and any
other relevant criteria. We will approve your plan if it supports the
objective of measuring emissions to represent a broad range of
operating characteristics.
    (b) Select vehicles and engines for testing that meet the following
criteria:
    (1) The vehicles come from at least two independent sources.
    (2) Powertrain, drivetrain, emission controls, and other key
vehicle and engine systems have been properly maintained and used. See
Sec.  1036.125.
    (3) The engines have not been tampered with, rebuilt, or undergone
major repair that could be expected to affect emissions.
    (4) The engines have not been misfueled. Do not consider engines
misfueled if they have used fuel meeting the specifications of Sec.
1036.415(c).
    (5) The vehicles are likely to operate for at least three hours of
non-idle operation over a complete shift-day, as described in Sec.
1036.415(f).
    (6) The vehicles have not exceeded the applicable useful life, in
miles, hours, or years; you may otherwise not exclude engines from
testing based on their age or mileage.
    (7) The vehicle has appropriate space for safe and proper mounting
of the portable emission measurement system (PEMS) equipment.
    (c) You must notify us before disqualifying any vehicle based on
illuminated MIL or stored OBD trouble codes as described in Sec.
1036.415(b)(2), or for any other reasons not specified in paragraph (b)
of this section. For example, notify us if you disqualify any vehicle
because the engine does not represent the engine family or the
vehicle's usage is atypical for the particular application. You do not
need to notify us in advance if the owner declines to participate in
the test program.

Sec.  1036.415  Preparing and testing engines.

    (a) You must limit maintenance to what is in the owners manual for
engines with that amount of service and age. For anything we consider
an adjustable parameter (see Sec.  1036.115(f)), you may adjust that
parameter only if it is outside its adjustable range. You must then set
the adjustable parameter to your recommended setting or the mid-point
of its adjustable range, unless we approve your request to do
otherwise. You must get our approval before adjusting anything not
considered an adjustable parameter. You must keep records of all
maintenance and adjustments, as required by Sec.  1036.435. You must
send us these records, as described in Sec.  1036.430(a)(2)(ix), unless
we instruct you not to send them.
    (b) You may treat a vehicle with an illuminated MIL or stored
trouble code as follows:
    (1) If a candidate vehicle has an illuminated MIL or stored trouble
code, either test the vehicle as received or repair the vehicle before
testing. Once testing is initiated on the vehicle, you accept that the
vehicle has been properly maintained and used.
    (2) If a MIL illuminates or a trouble code appears on a test
vehicle during a field test, stop the test and repair the vehicle.
Determine test results as specified in Sec.  1036.530 using one of the
following options:
    (i) Restart the testing and use only the portion of the full test
results without the MIL illuminated or trouble code set.
    (ii) Initiate a new test and use only the post-repair test results.
    (3) If you determine that repairs are needed but they cannot be
completed in a timely manner, you may disqualify the vehicle and
replace it with another vehicle.
    (c) Use appropriate fuels for testing, as follows:
    (1) You may use any diesel fuel that meets the specifications for
S15 in ASTM D975 (incorporated by reference in Sec.  1036.810). You may
use any commercially available biodiesel fuel blend that meets the
specifications for ASTM D975 or ASTM D7467 (incorporated by reference
in Sec.  1036.810) that is either expressly allowed or not otherwise
indicated as an unacceptable fuel in the vehicle's owner or operator
manual or in the engine manufacturer's published fuel recommendations.
You may use any gasoline fuel that meets the specifications in ASTM
D4814 (incorporated by reference in Sec.  1036.810). For other fuel
types, you may use any commercially available fuel.
    (2) You may drain test vehicles' fuel tanks and refill them with
diesel fuel conforming to the specifications in paragraph (c)(1) of
this section.
    (3) Any fuel that is added to a test vehicle's fuel tanks must be
purchased at a local retail establishment near the site of vehicle
recruitment or screening, or along the test route. Alternatively, the
fuel may be drawn from a central fueling source, as long as the fuel
represents commercially available fuel in the area of testing.
    (4) No post-refinery fuel additives are allowed, except that
specific fuel additives may be used during field testing if you can
document that the test vehicle has a history of normally using the fuel
treatments and they are not prohibited in the owners manual or in your
published fuel-additive recommendations.
    (5) You may take fuel samples from test vehicles to ensure that
appropriate fuels were used during field testing. If a vehicle fails
the vehicle-pass criteria and you can show that an inappropriate fuel
was used during the failed test, that particular test may be voided.
You may drain vehicles' fuel tanks and refill them with diesel fuel
conforming to the specifications described in paragraph (c)(1) of this
section. You must report any fuel tests that are the basis of voiding a
test in your report under Sec.  1036.430.
    (d) You must test the selected engines using the test procedure
described in Sec.  1036.530 while they remain installed in the vehicle.
Testing consists of characterizing emission rates for moving average
300 second windows while driving, with those windows divided into bins
representing different types of engine operation over a shift-day.
Measure emissions as follows:
    (1) Perform all testing with PEMS and field-testing procedures
referenced in 40 CFR part 1065, subpart J. Measure emissions of
NOX, CO, and CO2. We may require you to also
measure emissions of HC and PM. You may determine HC emissions by any
method specified in 40 CFR 1065.660(b).
    (2) If the engine's crankcase discharges emissions into the ambient
atmosphere, as allowed by Sec.  1036.115(a), you must either route all
crankcase emissions into the exhaust for a combined measurement or add
the crankcase emission values specified in Sec.  1036.240(e) to
represent emission levels at full useful life instead of measuring
crankcase emissions in the field.
    (e) Operate the test vehicle under conditions reasonably expected
during normal operation. For the purposes of this subpart, normal
operation generally includes the vehicle's normal routes and loads
(including auxiliary loads such as air conditioning in the cab), normal
ambient conditions, and the normal driver.
    (f) Once an engine is set up for testing, test the engine for one
shift-day, except as allowed in Sec.  1036.420(d). To complete a shift-
day's worth of testing,

start sampling at the beginning of a shift and continue sampling for
the whole shift, subject to the calibration requirements of the PEMS. A
shift-day is the period of a normal workday for an individual employee.
Evaluate the emission data as described in Sec.  1036.420 and include
the data in the reporting and record keeping requirements specified in
Sec. Sec.  1036.430 and 1036.435.
    (g) For stop-start and automatic engine shutdown systems meeting
the specifications of 40 CFR 1037.660, override idle-reduction features
if they are adjustable under 40 CFR 1037.520(j)(4). If those systems
are tamper-resistant under 40 CFR 1037.520(j)(4), set the 1-Hz emission
rate to zero for all regulated pollutants when the idle-reduction
feature is active. Do not exclude these data points under Sec.
1036.530(c)(3)(ii).

Sec.  1036.420  Pass criteria for individual engines.

    Perform the following steps to determine whether an engine meets
the binned emission standards in Sec.  1036.104(a)(3):
    (a) Determine the emission standard for each regulated pollutant
for each bin by adding the following accuracy margins for PEMS to the
off-cycle standards in Sec.  1036.104(a)(3):

                Table 1 to Paragraph (a) of Sec.   1036.420--Accuracy Margins for In-Use Testing
----------------------------------------------------------------------------------------------------------------
                                       NOX                HC                PM                     CO
----------------------------------------------------------------------------------------------------------------
Bin 1.........................  0.4 g/hr.........
Bin 2.........................  5 mg/hp[middot]hr  10 mg/            6 mg/             0.025 g/hp[middot]hr.
                                                    hp[middot]hr.     hp[middot]hr.
----------------------------------------------------------------------------------------------------------------

    (b) Calculate the mass emission rate for each pollutant as
specified in Sec.  1036.530.
    (c) For engines subject to compression-ignition standards,
determine the number of windows in each bin. A bin is valid under this
section only if it has at least 2,400 windows for bin 1 and 10,000
windows for bin 2.
    (d) Continue testing additional shift-days as necessary to achieve
the minimum window requirements for each bin. You may idle the engine
at the end of the shift day to increase the number of windows in bin 1.
If the vehicle has tamper-resistant idle-reduction technology that
prevents idling, populate bin 1 with additional windows by setting the
1-Hz emission rate for all regulated pollutants to zero as described in
Sec.  1036.415(g) to achieve exactly 2,400 bin 1 windows.
    (e) An engine passes if the result for each bin is at or below the
standard determined in paragraph (a) of this section. An engine fails
if the result for any bin for any pollutant is above the standard
determined in paragraph (a) of this section.

Sec.  1036.425  Pass criteria for engine families.

    For testing with PEMS under Sec.  1036.415(d)(1), determine the
number of engines you must test from each selected engine family and
the family pass criteria as follows:
    (a) Start by measuring emissions from five engines using the
procedures described in this subpart E and Sec.  1036.530. If all five
engines comply fully with the off-cycle bin standards, the engine
family passes, and you may stop testing.
    (b) If only one of the engines tested under paragraph (a) of this
section does not comply fully with the off-cycle bin standards, test
one more engine. If this additional engine complies fully with the off-
cycle bin standards, the engine family passes, and you may stop
testing.
    (c) If two or more engines tested under paragraphs (a) and (b) of
this section do not comply fully with the off-cycle bin standards, test
additional engines until you have tested a total of ten engines.
Calculate the arithmetic mean of the bin emissions from the ten engine
tests as specified in Sec.  1036.530(g) for each pollutant. If the mean
values are at or below the off-cycle bin standards, the engine family
passes. If the mean value for any pollutant is above an off-cycle bin
standard, the engine family fails.
    (d) You may accept a fail result for the engine family and
discontinue testing at any point in the sequence of testing the
specified number of engines.

Sec.  1036.430  Reporting requirements.

    (a) Report content. Prepare test reports as follows:
    (1) Include the following for each engine family:
    (i) Describe how you recruited vehicles. Describe how you used any
criteria or thresholds to narrow your search or to screen individual
vehicles.
    (ii) Include a summary of the vehicles you have disqualified and
the reasons you disqualified them, whether you base the
disqualification on the criteria in Sec.  1036.410(b), owner
nonparticipation, or anything else. If you disqualified a vehicle due
to misfueling, include the results of any fuel sample tests. If you
reject a vehicle due to tampering, describe how you determined that
tampering occurred.
    (iii) Identify how many engines you have tested from the applicable
engine family and how many engines still need to be tested. Identify
how many tested engines have passed or failed under Sec.  1036.420.
    (iv) After the final test, report the results and state the outcome
of testing for the engine family based on the criteria in Sec.
1036.425.
    (v) Describe any incomplete or invalid tests that were conducted
under this subpart.
    (2) Include the following information for the test vehicle:
    (i) The EPA engine-family designation, and the engine's model
number, total displacement, and power rating.
    (ii) The date EPA selected the engine family for testing.
    (iii) The vehicle's make and model and the year it was built.
    (iv) The vehicle identification number and engine serial number.
    (v) The vehicle's type or application (such as delivery, line haul,
or dump truck). Also, identify the type of trailer, if applicable.
    (vi) The vehicle's maintenance and use history.
    (vii) The known status history of the vehicle's OBD system and any
actions taken to address OBD trouble codes or MIL illumination over the
vehicle's lifetime.
    (viii) Any OBD codes or MIL illumination that occur after you
accept the vehicle for field testing under this subpart.
    (ix) Any steps you take to maintain, adjust, modify, or repair the
vehicle or its engine to prepare for or continue testing, including
actions to address OBD trouble codes or MIL illumination. Include any
steps you took to drain and refill the vehicle's fuel tank(s) to
correct misfueling, and the results of any fuel test conducted to
identify misfueling.
    (3) Include the following data and measurements for each test
vehicle:
    (i) The date and time of testing, and the test number.

    (ii) Number of shift-days of testing (see Sec.  1036.415(f)).
    (iii) Route and location of testing. You may base this description
on the output from a global-positioning system (GPS).
    (iv) The steps you took to ensure that vehicle operation during
testing was consistent with normal operation and use, as described in
Sec.  1036.415(e).
    (v) Fuel test results, if fuel was tested under Sec.  1036.410 or
Sec.  1036.415.
    (vi) The vehicle's mileage at the start of testing. Include the
engine's total lifetime hours of operation, if available.
    (vii) The number of windows in each bin (see Sec.  1036.420(c)).
    (viii) The bin emission value per vehicle for each pollutant.
Describe the method you used to determine HC as specified in 40 CFR
1065.660(b).
    (ix) Recorded 1 Hz test data for at least the following parameters,
noting that gaps in the 1 Hz data file over the shift-day are only
allowed during analyzer zero and span verifications and during engine
shutdown when the engine is keyed off:
    (A) Ambient temperature.
    (B) Ambient pressure.
    (C) Ambient humidity.
    (D) Altitude.
    (E) Emissions of HC, CO, CO2, and NOX. Report
results for PM if it was measured in a manner that provides 1 Hz test
data.
    (F) Differential backpressure of any PEMS attachments to vehicle
exhaust.
    (G) Exhaust flow.
    (H) Exhaust aftertreatment temperatures.
    (I) Engine speed.
    (J) Engine brake torque.
    (K) Engine coolant temperature
    (L) Intake manifold temperature.
    (M) Intake manifold pressure.
    (N) Throttle position.
    (O) Any parameter sensed or controlled, available over the
Controller Area Network (CAN) network, to modulate the emission control
system or fuel-injection timing.
    (4) Include the following summary information after you complete
testing with each engine:
    (i) State whether the engine meets the off-cycle standards for each
bin for each pollutant as described in Sec.  1036.420(e).
    (ii) Describe if any testing or evaluations were conducted to
determine why a vehicle failed the off-cycle emission standards
described in Sec.  1036.420.
    (iii) Describe the purpose of any diagnostic procedures you
conduct.
    (iv) Describe any instances in which the OBD system illuminated the
MIL or set trouble codes. Also describe any actions taken to address
the trouble codes or MIL.
    (v) Describe any instances of misfueling, the approved actions
taken to address the problem, and the results of any associated fuel
sample testing.
    (vi) Describe the number and length of any data gaps in the 1 Hz
data file, the reason for the gap(s), and the parameters affected.
    (b) Submission. Send electronic reports to the Designated
Compliance Officer using an approved information format. If you want to
use a different format, send us a written request with justification.
    (1) You may send us reports as you complete testing for an engine
instead of waiting until you complete testing for all engines.
    (2) We may ask you to send us less information in your reports than
we specify in this section.
    (3) We may require you to send us more information to evaluate
whether your engine family meets the requirements of this part.
    (4) Once you send us information under this section, you need not
send that information again in later reports.
    (c) Additional notifications. Notify the Designated Compliance
Officer describing progress toward completing the required testing and
reporting under this subpart, as follows:
    (1) Notify us once you complete testing for an engine.
    (2) Notify us if your review of the test data for an engine family
indicates that two of the first five tested engines have failed to
comply with the vehicle-pass criteria in Sec.  1036.420(e).
    (3) Notify us if your review of the test data for an engine family
indicates that the engine family does not comply with the family-pass
criteria in Sec.  1036.425(c).
    (4) Describe any voluntary vehicle/engine emission evaluation
testing you intend to conduct with PEMS on the same engine families
that are being tested under this subpart, from the time that engine
family was selected for field testing under Sec.  1036.405 until the
final results of all testing for that engine family are reported to us
under this section.

Sec.  1036.435  Recordkeeping requirements.

    Keep the following paper or electronic records of your field
testing for five years after you complete all the testing required for
an engine family:
    (a) Keep a copy of the reports described in Sec.  1036.430.
    (b) Keep any additional records, including forms you create,
related to any of the following:
    (1) The recruitment, screening, and selection process described in
Sec.  1036.410, including the vehicle owner's name, address, phone
number, and email address.
    (2) Pre-test maintenance and adjustments to the engine performed
under Sec.  1036.415.
    (3) Test results for all void, incomplete, and voluntary testing
described in Sec.  1036.430.
    (4) Evaluations to determine why an engine failed any of the bin
standards described in Sec.  1036.420.
    (c) Keep a copy of the relevant calibration results required by 40
CFR part 1065.

Sec.  1036.440  Warranty obligations related to in-use testing.

    Testing under this subpart that finds an engine exceeding emission
standards under this subpart is not by itself sufficient to show a
breach of warranty under 42 U.S.C. 7541(a)(1). A breach of warranty
would also require that engines fail to meet one or both of the
conditions specified in Sec.  1036.120(a).

Subpart F--Test Procedures

Sec.  1036.501  General testing provisions.

    (a) Use the equipment and procedures specified in this subpart and
40 CFR part 1065 to determine whether engines meet the emission
standards in Sec. Sec.  1036.104 and 1036.108.
    (b) Use the fuels specified in 40 CFR part 1065 to perform valid
tests, as follows:
    (1) For service accumulation, use the test fuel or any commercially
available fuel that is representative of the fuel that in-use engines
will use.
    (2) For diesel-fueled engines, use the ultra-low-sulfur diesel fuel
specified in 40 CFR part 1065.703 and 40 CFR 1065.710(b)(3) for
emission testing.
    (3) For gasoline-fueled engines, use the appropriate E10 fuel
specified in 40 CFR part 1065.
    (c) For engines that use aftertreatment technology with infrequent
regeneration events, apply infrequent regeneration adjustment factors
for each duty cycle as described in Sec.  1036.580.
    (d) If your engine is intended for installation in a vehicle
equipped with stop-start technology meeting the specifications of 40
CFR 1037.660 to qualify as tamper-resistant under 40 CFR
1037.520(j)(4), you may shut the engine down during idle portions of
the duty cycle to represent in-use operation. We recommend installing a
production engine starter motor and letting the engine's ECM manipulate
the starter motor to control the engine stop and start events. Use good
engineering judgment to address the effects of dynamometer inertia on
restarting the engine by, for example, using a larger starter motor or
declutching the engine from the dynamometer during restart.

    (e) You may use special or alternate procedures to the extent we
allow them under 40 CFR 1065.10.
    (f) This subpart is addressed to you as a manufacturer, but it
applies equally to anyone who does testing for you, and to us when we
perform testing to determine if your engines meet emission standards.

Sec.  1036.505  Engine data and information to support vehicle
certification.

    You must give vehicle manufacturers information as follows so they
can certify their vehicles to greenhouse gas emission standards under
40 CFR part 1037:
    (a) Identify engine make, model, fuel type, combustion type, engine
family name, calibration identification, and engine displacement. Also
identify whether the engines meet CO2 standards for
tractors, vocational vehicles, or both.
    (b) This paragraph (b) describes four different methods to generate
engine fuel maps. For engines without hybrid components and for mild
hybrid engines where you do not include hybrid components in the test,
generate fuel maps using either paragraph (b)(1) or (2) of this
section. For other hybrid engines, generate fuel maps using paragraph
(b)(3) of this section. For hybrid and nonhybrid powertrains and for
vehicles where the transmission is not automatic, automated manual,
manual, or dual-clutch, generate fuel maps using paragraph (b)(4) of
this section.
    (1) Determine steady-state engine fuel maps as described in Sec.
1036.535(b). Determine fuel consumption at idle as described in Sec.
1036.535 (c). Determine cycle-average engine fuel maps as described in
Sec.  1036.540, excluding cycle-average fuel maps for highway cruise
cycles.
    (2) Determine steady-state fuel maps as described in either Sec.
1036.535(b) or (d). Determine fuel consumption at idle as described in
Sec.  1036.535(c). Determine cycle-average engine fuel maps as
described in Sec.  1036.540, including cycle-average engine fuel maps
for highway cruise cycles. We may do confirmatory testing by creating
cycle-average fuel maps from steady-state fuel maps created in
paragraph (b)(1) of this section for highway cruise cycles. In Sec.
1036.540 we define the vehicle configurations for testing; we may add
more vehicle configurations to better represent your engine's operation
for the range of vehicles in which your engines will be installed (see
40 CFR 1065.10(c)(1)).
    (3) Determine fuel consumption at idle as described in Sec.
1036.535(c) and (d) and determine cycle-average engine fuel maps as
described in 40 CFR 1037.550, including cycle-average engine fuel maps
for highway cruise cycles. Set up the test to apply accessory load for
all operation by primary intended service class as described in the
following table:

     Table 1 to Paragraph (b)(3) of Sec.   1036.505--Accessory Load
------------------------------------------------------------------------
                                                              Power
                                                          representing
            Primary intended service class               accessory load
                                                              (kW)
------------------------------------------------------------------------
Light HDV.............................................               1.5
Medium HDV............................................               2.5
Heavy HDV.............................................               3.5
------------------------------------------------------------------------

    (4) Generate powertrain fuel maps as described in 40 CFR 1037.550
instead of fuel mapping under Sec.  1036.535 or Sec.  1036.540. Note
that the option in 40 CFR 1037.550(b)(2) is allowed only for hybrid
engine testing. Disable stop-start systems and automatic engine
shutdown systems when conducting powertrain fuel map testing using 40
CFR 1037.550.
    (c) Provide the following information if you generate engine fuel
maps using either paragraph (b)(1), (2), or (3) of this section:
    (1) Full-load torque curve for installed engines and the full-load
torque curve of the engine (parent engine) with the highest fueling
rate that shares the same engine hardware, including the turbocharger,
as described in 40 CFR 1065.510. You may use 40 CFR 1065.510(b)(5)(i)
for Spark-ignition HDE. Measure the torque curve for hybrid engines
that have an RESS as described in 40 CFR 1065.510(g)(2) with the hybrid
system active. Test hybrid engines with no RESS as described in 40 CFR
1065.510(b)(5)(ii).
    (2) Motoring torque curve as described in 40 CFR 1065.510(c)(2) and
(5) for nonhybrid and hybrid engines, respectively. For engines with a
low-speed governor, remove data points where the low-speed governor is
active. If you don't know when the low-speed governor is active, we
recommend removing all points below 40 r/min above the warm low-idle
speed.
    (3) Declared engine idle speed. For vehicles with manual
transmissions, this is the engine speed with the transmission in
neutral. For all other vehicles, this is the engine's idle speed when
the transmission is in drive.
    (4) The engine idle speed during the transient cycle-average fuel
map.
    (5) The engine idle torque during the transient cycle-average fuel
map.
    (d) If you generate powertrain fuel maps using paragraph (b)(4) of
this section, determine the system continuous rated power according to
Sec.  1036.520.

Sec.  1036.510  Supplemental Emission Test.

    (a) Measure emissions using the steady-state SET duty cycle as
described in this section. Note that the SET duty cycle is operated as
a ramped-modal cycle rather than discrete steady-state test points.
    (b) Perform SET testing with one of the following procedures:
    (1) For testing nonhybrid engines, the SET duty cycle is based on
normalized speed and torque values relative to certain maximum values.
Denormalize speed as described in 40 CFR 1065.512. Denormalize torque
as described in 40 CFR 1065.610(d). Note that idle points are to be run
at conditions simulating neutral or park on the transmission.
    (2) Test hybrid engines and hybrid powertrains as described in 40
CFR 1037.550, except as specified in this paragraph (b)(2). Do not
compensate the duty cycle for the distance driven as described in 40
CFR 1037.550(g)(4). For hybrid engines, select the transmission from
Table 1 of Sec.  1036.540, substituting ``engine'' for ``vehicle'' and
``highway cruise cycle'' for ``SET''. Disregard duty cycles in 40 CFR
1037.550(j). For cycles that begin with idle, leave the transmission in
neutral or park for the full initial idle segment. Place the
transmission into drive no earlier than 5 seconds before the first
nonzero vehicle speed setpoint. For SET testing only, place the
transmission into park or neutral when the cycle reaches the final idle
segment. Use the following vehicle parameters instead of those in 40
CFR 1037.550 to define the vehicle model in 40 CFR 1037.550(a)(3):
    (i) Determine the vehicle test mass, M, as follows:
    [GRAPHIC] [TIFF OMITTED] TR24JA23.016

Where:

Pcontrated = the continuous rated power of the hybrid
system determined in sect; 1036.520.

Example:

Pcontrated = 350.1 kW
M = 15.1[middot]350.1\1.31\
M = 32499 kg

    (ii) Determine the vehicle frontal area, Afront, as
follows:
    (A) For M <= 18050 kg:

[GRAPHIC] [TIFF OMITTED] TR24JA23.017

Example:

M = 16499 kg
Afront =
-1.69[middot]10-\8\[middot]16499\2\+6.33[middot]10
-\4\[middot]16499+1.67
Afront = 7.51 m\2\

    (B) For M > 18050 kg, Afront = 7.59 m\2\
    (iii) Determine the vehicle drag area, CdA, as follows:
    [GRAPHIC] [TIFF OMITTED] TR24JA23.018

Where:

g = gravitational constant = 9.80665 m/s\2\.
[rho] = air density at reference conditions. Use [rho] = 1.1845 kg/
m\3\.

Example:
[GRAPHIC] [TIFF OMITTED] TR24JA23.019

    CdA = 3.08 m\2\

    (iv) Determine the coefficient of rolling resistance,
Crr, as follows:
[GRAPHIC] [TIFF OMITTED] TR24JA23.020

Example:
[GRAPHIC] [TIFF OMITTED] TR24JA23.021

Crr = 5.7 N/kN = 0.0057 N/N

    (v) Determine the vehicle curb mass, Mcurb, as follows:
    [GRAPHIC] [TIFF OMITTED] TR24JA23.022

Example:

Mcurb = -0.000007376537[middot]32499\2\ +
0.6038432[middot]32499
Mcurb = 11833 kg

    (vi) Determine the linear equivalent mass of rotational moment of
inertias, Mrotating, as follows:
[GRAPHIC] [TIFF OMITTED] TR24JA23.023

Example:

Mrotating = 0.07[middot]11833
Mrotating = 828.3 kg

    (vii) Select a drive axle ratio, ka, that represents the
worst-case combination of final gear ratio, drive axle ratio, and tire
size for CO2 expected for vehicles in which the hybrid
powertrain or hybrid engine will be installed. This is typically the
highest axle ratio.
    (viii) Select a tire radius, r, that represents the worst-case pair
of tire size and drive axle ratio for CO2 expected for
vehicles in which the hybrid powertrain or hybrid engine will be
installed. This is typically the smallest tire radius.
    (ix) If you are certifying a hybrid engine, use a default
transmission efficiency of 0.95 and create the vehicle model along with
its default transmission shift strategy as described in 40 CFR
1037.550(a)(3)(ii). Use the transmission parameters defined in Table 1
of Sec.  1036.540 to determine transmission type and gear ratio. For
Light HDV and Medium HDV, use the Light HDV and Medium HDV parameters
for FTP, LLC, and SET duty cycles. For Tractors and Heavy HDVs, use the
Tractor and Heavy HDV transient cycle parameters for the FTP and LLC
duty cycles and the Tractor and Heavy HDV highway cruise cycle
parameters for the SET duty cycle.
    (c) Measure emissions using the SET duty cycle shown in Table 1 of
this section to determine whether engines meet the steady-state
compression-ignition standards specified in subpart B of this part.
Table 1 of this section specifies test settings, as follows:
    (1) The duty cycle for testing nonhybrid engines involves a
schedule of normalized engine speed and torque values. Note that
nonhybrid powertrains are generally tested as engines, so this section
does not describe separate procedures for that configuration.
    (2) The duty cycle for testing hybrid engines and hybrid
powertrains involves a schedule of vehicle speeds and road grade as
follows:
    (i) Determine road grade at each point based on the continuous
rated power of the hybrid powertrain system, Pcontrated, in
kW determined in Sec.  1036.520, the vehicle speed (A, B, or C) in mi/
hr for a given SET mode, vref[speed], and the specified
road-grade coefficients using the following equation:

[GRAPHIC] [TIFF OMITTED] TR24JA23.024

Example for SET mode 3a in Table 1 of this section:

Pcontrated = 345.2 kW
vrefB = 59.3 mi/hr
Road grade = 8.296 [middot] 10-\9\ [middot] 345.2\3\ +
(-4.752 [middot] 10-\7\) [middot] 345.2\2\
[middot] 59.3 + 1.291 [middot] 10-\5\ [middot] 345.2\2\ +
2.88 [middot] 10-\4\ [middot] 59.3\2\ + 4.524 [middot]
10-\4\ [middot] 345.2 [middot] 59.3 + (-1.802
[middot] 10-\2\) [middot] 345.2 + (-1.83 [middot]
10-\1\) [middot] 59.3 + 8.81
Road grade = 0.53%

    (ii) Use the vehicle C speed determined in Sec.  1036.520.
Determine vehicle A and B speeds as follows:
    (A) Determine vehicle A speed using the following equation:
    [GRAPHIC] [TIFF OMITTED] TR24JA23.025

Example:

vrefC = 68.42 mi/hr
[GRAPHIC] [TIFF OMITTED] TR24JA23.026

vrefA = 50.2 mi/hr

    (B) Determine vehicle B speed using the following equation:
    [GRAPHIC] [TIFF OMITTED] TR24JA23.027

Example:
[GRAPHIC] [TIFF OMITTED] TR24JA23.028

vrefB = 59.3 mi/hr

    (3) Table 1 follows:
BILLING CODE 6560-50-P

[GRAPHIC] [TIFF OMITTED] TR24JA23.029

BILLING CODE 6560-50-C
    (d) Determine criteria pollutant emissions for plug-in hybrid
engines and powertrains as follows:
    (1) Precondition the engine or powertrain in charge-sustaining
mode. Perform testing as described in this section for hybrid engines
and hybrid powertrains in charge-sustaining mode.
    (2) Carry out a charge-depleting test as described in paragraph
(d)(1) of this section, except as follows:
    (i) Fully charge the RESS after preconditioning.
    (ii) Operate the hybrid engine or powertrain continuously over
repeated SET duty cycles until you reach the end-of-test criterion
defined in 40 CFR 1066.501(a)(3).
    (iii) Calculate emission results for each SET duty cycle. Figure 1
of this section provides an example of a charge-depleting test sequence
where there are two test intervals that contain engine operation.
    (3) Report the highest emission result for each criteria pollutant
from all tests in paragraphs (d)(1) and (2) of this section, even if
those individual results come from different test intervals.
    (4) Figure 1 follows:

Figure 1 to Paragraph (d)(4) of Sec.  1036.510--SET Charge-Depleting
Criteria Pollutant Test Sequence
[GRAPHIC] [TIFF OMITTED] TR24JA23.030

    (e) Determine greenhouse gas pollutant emissions for plug-in hybrid
engines and powertrains using the emissions results for all the SET
test intervals for both charge-depleting and charge-sustaining
operation from paragraph (d)(2) of this section. Calculate the utility
factor-weighted composite mass of emissions from the charge-depleting
and charge-sustaining test results, eUF[emission]comp, using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.031

Where:
i = an indexing variable that represents one test interval.
N = total number of charge-depleting test intervals.
e[emission][int]CDi = total mass of emissions in the
charge-depleting portion of the test for each test interval, i,
starting from i = 1, including the test interval(s) from the
transition phase.
UFDCDi = utility factor fraction at distance
DCDi from Eq. 1036.510-11, as determined by
interpolating the approved utility factor curve for each test
interval, i, starting from i = 1. Let UFDCD0 = 0.
j = an indexing variable that represents one test interval.
M = total number of charge-sustaining test intervals.
e[emission][int]CSj = total mass of emissions
in the charge-sustaining portion of the test for each test interval,
j, starting from j = 1.
UFRCD = utility factor fraction at the full charge-
depleting distance, RCD, as determined by interpolating
the approved utility factor curve. RCD is the cumulative
distance driven over N charge-depleting test intervals.
[GRAPHIC] [TIFF OMITTED] TR24JA23.032

Where:

k = an indexing variable that represents one recorded velocity
value.
Q = total number of measurements over the test interval.
v = vehicle velocity at each time step, k, starting from k = 1. For
tests completed under this section, v is the vehicle velocity from
the vehicle model in 40 CFR 1037.550. Note that this should

include charge-depleting test intervals that start when the engine
is not yet operating.
[Delta]t = 1/frecord
frecord = the record rate.

Example using the charge-depletion test in Figure 1 of Sec.  1036.510
for the SET for CO2 emission determination:

Q = 24000
v1 = 0 mi/hr
v2 = 0.8 mi/hr
v3 = 1.1 mi/hr
frecord = 10 Hz
[Delta]t = 1/10 Hz = 0.1 s
[GRAPHIC] [TIFF OMITTED] TR24JA23.033

DCD1 = 30.1 mi
DCD2 = 30.0 mi
DCD3 = 30.1 mi
DCD4 = 30.2 mi
DCD5 = 30.1 mi
N = 5
UFDCD1 = 0.11
UFDCD2 = 0.23
UFDCD3 = 0.34
UFDCD4 = 0.45
UFDCD5 = 0.53
eCO2SETCD1 = 0 g/hp[middot]hr
eCO2SETCD2 = 0 g/hp[middot]hr
eCO2SETCD3 = 0 g/hp[middot]hr
eCO2SETCD4 = 0 g/hp[middot]hr
eCO2SETCD5 = 174.4 g/hp[middot]hr
M = 1
eCO2SETCS = 428.1 g/hp[middot]hr
UFRCD = 0.53
[GRAPHIC] [TIFF OMITTED] TR24JA23.034

eUFCO2comp = 215.2 g/hp[middot]hr
    (f) Calculate and evaluate cycle statistics as specified in 40 CFR
1065.514 for nonhybrid engines and 40 CFR 1037.550 for hybrid engines
and hybrid powertrains.
    (g) Calculate cycle work for powertrain testing using system power,
Psys. Determine Psys, using Sec.  1036.520(f).

Sec.  1036.512  Federal Test Procedure.

    (a) Measure emissions using the transient Federal Test Procedure
(FTP) as described in this section to determine whether engines meet
the emission standards in subpart B of this part. Operate the engine or
hybrid powertrain over one of the following transient duty cycles:
    (1) For engines subject to spark-ignition standards, use the
transient test interval described in paragraph (b) of appendix B of
this part.
    (2) For engines subject to compression-ignition standards, use the
transient test interval described in paragraph (c) of appendix B of
this part.
    (b) The following procedures apply differently for testing engines
and hybrid powertrains:
    (1) The transient test intervals for nonhybrid engine testing are
based on normalized speed and torque values. Denormalize speed as
described in 40 CFR 1065.512. Denormalize torque as described in 40 CFR
1065.610(d).
    (2) Test hybrid engines and hybrid powertrains as described in
Sec.  1036.510(b)(2), with the following exceptions:
    (i) Replace Pcontrated with Prated, which is
the peak rated power determined in Sec.  1036.520.
    (ii) Keep the transmission in drive for all idle segments after the
initial idle segment.
    (iii) For hybrid engines, select the transmission from Table 1 of
Sec.  1036.540, substituting ``engine'' for ``vehicle''.
    (iv) For hybrid engines, you may request to change the engine-
commanded torque at idle to better represent curb idle transmission
torque (CITT).
    (v) For plug-in hybrid engines and powertrains, test over the FTP
in both charge-sustaining and charge-depleting operation for both
criteria and greenhouse gas pollutant determination.
    (c) The FTP duty cycle consists of an initial run through the test
interval from a cold start as described in 40 CFR part 1065, subpart F,
followed by a (20 1) minute hot soak with no engine
operation, and then a final hot start run through the same transient
test interval. Engine starting is part of both the cold-start and hot-
start test intervals. Calculate the total emission mass of each
constituent, m, and the total work, W, over each test interval as
described in 40 CFR 1065.650. Calculate total work over each test
interval for powertrain testing using system power, Psys.
Determine Psys using Sec.  1036.520(f). For powertrains with
automatic transmissions, account for and include the work produced by
the engine from the CITT load. Calculate the official transient
emission result from the cold-start and hot-start test intervals using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.035

    (d) Determine criteria pollutant emissions for plug-in hybrid
engines and powertrains as follows:
    (1) Precondition the engine or powertrain in charge-sustaining
mode. Perform testing as described in this section for hybrid engines
and hybrid powertrains in charge-sustaining mode.
    (2) Carry out a charge-depleting test as described in paragraph
(d)(1) of this section, except as follows:
    (i) Fully charge the battery after preconditioning.
    (ii) Operate the hybrid engine or powertrain over one FTP duty
cycle followed by alternating repeats of a 20-minute soak and a hot
start test interval

until you reach the end-of-test criteria defined in 40 CFR 1066.501.
    (iii) Calculate emission results for each successive pair of test
intervals. Calculate the emission result by treating the first of the
two test intervals as a cold-start test. Figure 1 of Sec.  1036.512
provides an example of a charge-depleting test sequence where there are
three test intervals with engine operation for two overlapping FTP duty
cycles.
    (3) Report the highest emission result for each criteria pollutant
from all tests in paragraphs (d)(1) and (2) of this section, even if
those individual results come from different test intervals.
    (4) Figure 1 follows:

Figure 1 to paragraph (d)(4) of Sec.  1036.512--FTP Charge-Depleting
Criteria Pollutant Test Sequence.
[GRAPHIC] [TIFF OMITTED] TR24JA23.036

    (e) Determine greenhouse gas pollutant emissions for plug-in hybrid
engines and powertrains using the emissions results for all the
transient duty cycle test intervals described in either paragraph (b)
or (c) of appendix B of this part for both charge-depleting and charge-
sustaining operation from paragraph (d)(2) of this section. Calculate
the utility factor weighted composite mass of emissions from the
charge-depleting and charge-sustaining test results,
eUF[emission]comp, as described in Sec.  1036.510(e),
replacing occurances of ``SET'' with ``transient test interval''. Note
this results in composite FTP GHG emission results for plug-in hybrid
engines and powertrains without the use of the cold-start and hot-start
test interval weighting factors in Eq. 1036.512-1.
    (f) Calculate and evaluate cycle statistics as specified in 40 CFR
1065.514 for nonhybrid engines and 40 CFR 1037.550 for hybrid engines
and hybrid powertrains.

Sec.  1036.514  Low Load Cycle.

    (a) Measure emissions using the transient Low Load Cycle (LLC) as
described in this section to determine whether engines meet the LLC
emission standards in Sec.  1036.104.
    (b) The LLC duty cycle is described in paragraph (d) of appendix B
of this part. The following procedures apply differently for testing
engines and hybrid powertrains:
    (1) For nonhybrid engine testing, the duty cycle is based on
normalized speed and torque values.
    (i) Denormalize speed as described in 40 CFR 1065.512. Denormalize
torque as described in 40 CFR 1065.610(d).
    (ii) For idle segments more than 200 seconds, set reference torques
to the torque needed to meet the accessory loads in Table 1 of this
section instead of CITT. This is to represent shifting the transmission
to park or neutral at the start of the idle segment. Change the
reference torque to CITT no earlier than 5 seconds before the end of
the idle segment. This is to represent shifting the transmission to
drive.
    (2) Test hybrid engines and hybrid powertrains as described in
Sec.  1036.510(b)(2), with the following exceptions:
    (i) Replace Pcontrated with Prated, which is
the peak rated power determined in Sec.  1036.520.
    (ii) Keep the transmission in drive for all idle segments 200
seconds or less. For idle segments more than 200 seconds, place the
transmission in park or neutral at the start of the idle segment and
place the transmission into drive again no earlier than 5 seconds
before the first nonzero vehicle speed setpoint.
    (iii) For hybrid engines, select the transmission from Table 1 of
Sec.  1036.540, substituting ``engine'' for ``vehicle''.
    (iv) For hybrid engines, you may request to change the engine-
commanded torque at idle to better represent curb idle transmission
torque (CITT).
    (v) For plug-in hybrid engines and powertrains, determine criteria
pollutant and greenhouse gas emissions as described in Sec.
1036.510(d) and (e), replacing ``SET'' with ``LLC''.
    (c) Set dynamometer torque demand such that vehicle power
represents an accessory load for all idle operation as described in
Table 1 of paragraph (c)(4) of this section for each primary intended
service class. Additional provisions related to accessory load apply
for the following special cases:
    (1) For engines with stop-start technology, account for accessory
load during engine-off conditions by determining the total engine-off
power demand over the test interval and distributing that load over the
engine-on portions of the test interval based on calculated average
power. You may determine the engine-off time by running practice cycles
or through engineering analysis.
    (2) Apply accessory loads for hybrid powertrain testing that
includes the

transmission either as a mechanical or electrical load.
    (3) You may apply the following deviations from specified torque
settings for smoother idle (other than idle that includes motoring), or
you may develop different procedures for adjusting accessory load at
idle consistent with good engineering judgment:
    (i) Set the reference torque to correspond to the applicable
accessory load for all points with normalized speed at or below zero
percent and reference torque from zero up to the torque corresponding
to the accessory load.
    (ii) Change the reference torques to correspond to the applicable
accessory load for consecutive points with reference torques from zero
up to the torque corresponding to the accessory load that immediately
precedes or follows idle points.
    (4) Table 1 follows:

 Table 1 to Paragraph (c)(4) of Sec.   1036.514--Accessory Load at Idle
------------------------------------------------------------------------
                                                               Power
                                                           representing
             Primary intended service class               accessory load
                                                               (kW)
------------------------------------------------------------------------
Light HDE...............................................             1.5
Medium HDE..............................................             2.5
Heavy HDE...............................................             3.5
------------------------------------------------------------------------

    (d) The test sequence consists of preconditioning the engine by
running one or two FTPs with each FTP followed by (20 1)
minutes with no engine operation and a hot start run through the LLC.
You may start any preconditioning FTP with a hot engine. Perform
testing as described in 40 CFR 1065.530 for a test interval that
includes engine starting. Calculate the total emission mass of each
constituent, m, and the total work, W, as described in 40 CFR 1065.650.
Calculate total work over the test interval for powertrain testing
using system power, Psys. Determine Psys using
Sec.  1036.520(f). For powertrains with automatic transmissions,
account for and include the work produced by the engine from the CITT
load. For batch sampling, you may sample background periodically into
the bag over the course of multiple test intervals.
    (e) Calculate and evaluate cycle statistics as specified in 40 CFR
1065.514 for nonhybrid engines and 40 CFR 1037.550 for hybrid engines
and hybrid powertrains. For gaseous-fueled engine testing with a
single-point fuel injection system, you may apply all the statistical
criteria in Sec.  1036.540(d)(3) to validate the LLC.

Sec.  1036.520  Determining power and vehicle speed values for
powertrain testing.

    This section describes how to determine the system peak power and
continuous rated power of hybrid and nonhybrid powertrain systems and
the vehicle speed for carrying out duty-cycle testing under this part
and 40 CFR 1037.550.
    (a) You must map or re-map an engine before a test if any of the
following apply:
    (1) If you have not performed an initial engine map.
    (2) If the atmospheric pressure near the engine's air inlet is not
within 5 kPa of the atmospheric pressure recorded at the
time of the last engine map.
    (3) If the engine or emission-control system has undergone changes
that might affect maximum torque performance. This includes changing
the configuration of auxiliary work inputs and outputs.
    (4) If you capture an incomplete map on your first attempt or you
do not complete a map within the specified time tolerance. You may
repeat mapping as often as necessary to capture a complete map within
the specified time.
    (b) Set up the powertrain test according to 40 CFR 1037.550, with
the following exceptions:
    (1) Use vehicle parameters, other than power, as specified in Sec.
1036.510(b)(2). Use the applicable automatic transmission as specified
in Sec.  1036.540(c)(2).
    (2) Select a manufacturer-declared value for Pcontrated
to represent system peak power.
    (c) Verify the following before the start of each test interval:
    (1) The state-of-charge of the rechargeable energy storage system
(RESS) must be at or above 90% of the operating range between the
minimum and maximum RESS energy levels specified by the manufacturer.
    (2) The conditions of all hybrid system components must be within
their normal operating range as declared by the manufacturer, including
ensuring that no features are actively limiting power or vehicle speed.
    (d) Carry out the test as described in this paragraph (d). Warm up
the powertrain by operating it. We recommend operating the powertrain
at any vehicle speed and road grade that achieves approximately 75% of
its expected maximum power. Continue the warm-up until the engine
coolant, block, or head absolute temperature is within 2%
of its mean value for at least 2 min or until the engine thermostat
controls engine temperature. Within 90 seconds after concluding the
warm-up, operate the powertrain over a continuous trace meeting the
following specifications:
    (1) Bring the vehicle speed to 0 mi/hr and let the powertrain idle
at 0 mi/hr for 50 seconds.
    (2) Set maximum driver demand for a full load acceleration at 6.0%
road grade with an initial vehicle speed of 0 mi/hr, continuing for 268
seconds.
    (3) Linearly ramp the grade from 6.0% down to 0.0% over 300
seconds. Stop the test 30 seconds after the grade setpoint has reached
0.0%.
    (e) Record the powertrain system angular speed and torque values
measured at the dynamometer at 100 Hz and use these in conjunction with
the vehicle model to calculate vehicle system power,
Psys,vehicle. Note that Psys, is the
corresponding value for system power at a location that represents the
transmission input shaft on a conventional powertrain.
    (f) Calculate the system power, Psys, for each data
point as follows:
    (1) For testing with the speed and torque measurements at the
transmission input shaft, Psys is equal to the calculated
vehicle system power, Psys,vehicle, determined in paragraphs
(d) and (e) of this section.
    (2) For testing with the speed and torque measurements at the axle
input shaft or the wheel hubs, determine Psys for each data
point using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.037

Where:

Psys,vehicle = the calculated vehicle system power for
each 100-Hz data point.
[egr]trans = the default transmission efficiency = 0.95.
[egr]axle = the default axle efficiency. Set this value
to 1 for speed and torque measurement at the axle input shaft or to
0.955 at the wheel hubs.

Example:

Psys,vehicle = 317.6 kW
[GRAPHIC] [TIFF OMITTED] TR24JA23.038

Psys = 350.1 kW
    (g) For each 200-ms (5-Hz) time step, t, determine the coefficient
of variation (COV) of as follows:
    (1) Calculate the standard deviation, [sigma](t) of the 20 100-Hz
data points in each 5-Hz measurement interval using the following
equation:

[GRAPHIC] [TIFF OMITTED] TR24JA23.039

Where:

N = the number of data points in each 5-Hz measurement interval =
20.
Psysi = the 100-Hz values of Psys within each
5-Hz measurement interval.
Psys(t) = the mean power from each 5-Hz measurement
interval.

    (2) Calculate the 5-Hz values for COV(t) for each time step, t, as
follows:
[GRAPHIC] [TIFF OMITTED] TR24JA23.040

    (h) Determine rated power, Prated, as the maximum
measured power from the data collected in paragraph (f)(2) of this
section that meets the specifications in paragraph (g) of this section.
    (i) Determine continuous rated power, Pcontrated, as
follows:
    (1) For nonhybrid powertrains, Pcontrated equals
Prated.
    (2) For hybrid powertrains, Pcontrated is the maximum
measured power from the data collected in paragraph (d)(3) of this
section that meets the specifications in paragraph (g) of this section.
    (j) Determine vehicle C speed, vrefC, as follows:
    (1) If the maximum Psys(t) in the highest gear during
the maneuver in paragraph (d)(3) of this section is greater than
0.98[middot]Pcontrated, vrefC is the average of
the minimum and maximum vehicle speeds where Psys(t) is
equal to 0.98[middot]Pcontrated during the maneuver in
paragraph (d)(3) of this section where the transmission is in the
highest gear, using linear interpolation, as appropriate.
    (2) Otherwise, vrefC is the maximum vehicle speed during
the maneuver in paragraph (d)(3) where the transmission is in the
highest gear.
    (k) If Pcontrated as determined in paragraph (i) of this
section is within 3% of the manufacturer-declared value for
Pcontrated, use the manufacturer-declared value. Otherwise,
repeat the procedure in paragraphs (b) through (j) of this section and
use Pcontrated from paragraph (i) instead of the
manufacturer-declared value.

Sec.  1036.525  Clean Idle test.

    Measure emissions using the procedures described in this section to
determine whether engines and hybrid powertrains meet the clean idle
emission standards in Sec.  1036.104(b). For plug-in hybrid engines and
powertrains, perform the test with the hybrid function disabled.
    (a) The clean idle test consists of two separate test intervals as
follows:
    (1) Mode 1 consists of engine operation with a speed setpoint at
your recommended warm idle speed. Set the dynamometer torque demand
corresponding to vehicle power requirements at your recommended warm
idle speed that represent in-use operation.
    (2) Mode 2 consists of engine operation with a speed setpoint at
1100 r/min. Set the dynamometer torque demand to account for the sum of
the following power loads:
    (i) Determine power requirements for idling at 1100 r/min.
    (ii) Apply a power demand of 2 kW to account for appliances and
accessories the vehicle operator may use during rest periods.
    (3) Determine torque demand for testing under this paragraph (a)
based on an accessory load that includes the engine cooling fan,
alternator, coolant pump, air compressor, engine oil and fuel pumps,
and any other engine accessory that operates at the specific test
condition. Also include the accessory load from the air conditioning
compressor operating at full capacity for Mode 2. Do not include any
other load for air conditioning or other cab or vehicle accessories
except as specified.
    (b) Perform the Clean Idle test as follows:
    (1) Warm up the engine by operating it over the FTP or SET duty
cycle, or by operating it at any speed above peak-torque speed and at
(65 to 85) % of maximum mapped power. The warm-up is complete when the
engine thermostat controls engine temperature or when the engine
coolant's temperature is within 2% of its mean value for at least 2
minutes.
    (2) Start operating the engine in Mode 1 as soon as practical after
the engine warm-up is complete.
    (3) Start sampling emissions 10 minutes after reaching the speed
and torque setpoints and continue emission sampling and engine
operation at those setpoints. Stop emission sampling after 1200 seconds
to complete the test interval.
    (4) Linearly ramp the speed and torque setpoints over 5 seconds to
start operating the engine in Mode 2. Sample emissions during Mode 2 as
described in paragraph (b)(3) of this section.
    (c) Verify that the test speed stays within 50 r/min of
the speed setpoint throughout the test. The torque tolerance is 2 percent of the maximum mapped torque at the test speed. Verify
that measured torque meets the torque tolerance relative to the torque
setpoint throughout the test.
    (d) Calculate the mean mass emission rate of NOX, mi,
over each test interval by calculating the total emission mass mi
NOx and dividing by the total time.

Sec.  1036.530  Test procedures for off-cycle testing.

    (a) General. This section describes the measurement and calculation
procedures to perform field testing and determine whether tested
engines and engine families meet emission standards under subpart E of
this part. Calculate mass emission rates as specified in 40 CFR part
1065, subpart G. Use good engineering judgment to adapt these
procedures for simulating vehicle operation in the laboratory.
    (b) Vehicle preparation and measurement procedures. (1) Set up the
vehicle for testing with a portable emissions measurement system (PEMS)
as specified in 40 CFR part 1065, subpart J.
    (2) Begin emission sampling and data collection as described in 40
CFR 1065.935(c)(3) before starting the engine at the beginning of the
shift-day. Start the engine only after confirming that engine coolant
temperature is at or below 40 [deg]C.
    (3) Measure emissions over one or more shift-days as specified in
subpart E of this part.
    (4) For engines subject to compression-ignition standards, record 1
Hz measurements of ambient temperature near the vehicle.
    (c) Test Intervals. Determine the test intervals as follows:
    (1) Spark-ignition. Create a single test interval that covers the
entire shift-day for engines subject to spark-ignition standards. The
test interval starts with the first pair of consecutive data points
with no exclusions as described in paragraph (c)(3) of this section
after the start of the shift-day and ends with the last pair of
consecutive data points with no exclusions before the end of the shift
day.
    (2) Compression-ignition. Create a series of 300 second test
intervals for engines subject to compression-ignition standards
(moving-average windows) as follows:
    (i) Begin and end each test interval with a pair of consecutive
data points with no exclusions as described in paragraph (c)(3) of this
section. Select the last data point of each test interval such that the
test interval includes 300 seconds of data with no exclusions, as
described in paragraph (d) of this section. The test interval may be a
fraction of a second more or less than 300 seconds to account for the
precision

of the time stamp in recording 1 Hz data. A test interval may include
up to 599 seconds of data with continuous exclusions; invalidate any
test interval that includes at least 600 seconds of continuous sampling
with excluded data.
    (ii) The first 300 second test interval starts with the first pair
of consecutive data points with no exclusions. Determine the start of
each subsequent 300 second test interval by finding the first pair of
consecutive data points with no exclusions after the initial data point
of the previous test interval.
    (iii) The last 300 second test interval ends with the last pair of
consecutive data points with no exclusions before the end of the shift
day.
    (3) Excluded data. Exclude data from test intervals for any period
meeting one or more of the following conditions:
    (i) An analyzer or flow meter is performing zero and span drift
checks or zero and span calibrations, including any time needed for the
analyzer to stabilize afterward, consistent with good engineering
judgment.
    (ii) The engine is off, except as specified in Sec.  1036.415(g).
    (iii) The engine is performing an infrequent regeneration. Do not
exclude data related to any other AECDs, except as specified in
paragraph (c)(3)(vi) of this section.
    (iv) The recorded ambient air temperature is below 5 [deg]C or
above the temperature calculated using the following equation.
[GRAPHIC] [TIFF OMITTED] TR24JA23.041

Where:

h = recorded elevation of the vehicle in feet above sea level (h is
negative for elevations below sea level).

Example:

h = 2679 ft
Tmax = -0.0014[middot]2679 + 37.78
Tmax = 34.0 [deg]C
    (v) The vehicle is operating at an elevation more than 5,500 feet
above sea level.
    (vi) An engine has one or more active AECDs for emergency vehicles
under Sec.  1036.115(h)(4).
    (vii) A single data point does not meet any of the conditions
specified in paragraphs (c)(3)(i) through (vi) of this section, but it
is preceded and followed by data points that both meet one or more of
the specified exclusion conditions.
    (d) Assembling test intervals. A test interval may include multiple
subintervals separated by periods with one or more exclusions under
paragraph (c)(3) of this section.
    (1) Treat these test subintervals as continuous for calculating
duration of the test interval for engines subject to compression-
ignition standards.
    (2) Calculate emission mass during each test subinterval and sum
those subinterval emission masses to determine the emission mass over
the test interval. Calculate emisson mass as described in 40 CFR
1065.650(c)(2)(i), with the following exceptions and clarifications:
    (i) Correct NOX emissions for humidity as specified in
40 CFR 1065.670. Calculate corrections relative to ambient air humidity
as measured by PEMS.
    (ii) Disregard the provision in 40 CFR 1065.650(g) for setting
negative emission mass to zero for test intervals and subintervals.
    (iii) Calculation of emission mass in 40 CFR 1065.650 assumes a
constant time interval, [Delta]t. If it is not appropriate to assume
[Delta]t is constant for testing under this section, use good
engineering judgment to record time at each data point and adjust the
mass calculation from Eq. 1065.650-4 by treating [Delta]t as a
variable.
    (e) Normalized CO2 emission mass over a 300 second test
interval. For engines subject to compression-ignition standards,
determine the normalized CO2 emission mass over each 300
second test interval, mCO2,norm,testinterval, to the nearest
0.01% using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.042

Where:

mCO2,testinterval = total CO2 emission mass
over the test interval.
eCO2FTPFCL = the engine's FCL for CO2 over the
FTP duty cycle. If the engine family includes no FTP testing, use
the engine's FCL for CO2 over the SET duty cycle.
Pmax = the highest value of rated power for all the
configurations included in the engine family.
ttestinterval = duration of the test interval. Note that
the nominal value is 300 seconds.

Example:

mCO2,testinterval = 3948 g
eCO2FTPFCL = 428.2 g/hp[middot]hrPmax = 406.5 hp
    ttestinterval = 300.01 s = 0.08 hr
    [GRAPHIC] [TIFF OMITTED] TR24JA23.043

mCO2,norm,testinterval = 0.2722 = 27.22%

    (f) Binning 300 second test intervals. For engines subject to
compression-ignition standards, identify the appropriate bin for each
of the 300 second test intervals based on its normalized CO2
emission mass, mCO2,norm,testinterval, as follows:

Table 1 to Paragraph (f) of Sec.   1036.530--Criteria for Off-Cycle Bins
------------------------------------------------------------------------
                                            Normalized CO2 emission mass
                    Bin                       over the 300 second test
                                                      interval
------------------------------------------------------------------------
Bin 1.....................................  mCO2,norm,testinterval <=
                                             6.00%.
Bin 2.....................................  mCO2,norm,testinterval >
                                             6.00%.
------------------------------------------------------------------------

    (g) Off-cycle emissions quantities. Determine the off-cycle
emissions quantities as follows:
    (1) Spark-ignition. For engines subject to spark-ignition
standards, the off cycle emission quantity,
e[emission],offcycle, is the value for CO2-
specific emission mass for a given pollutant over the test interval
representing the shift-day converted to a brake-specific value, as
calculated for

each measured pollutant using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.044

Where:

m[emission] = total emission mass for a given pollutant
over the test interval as determined in paragraph (d)(2) of this
section.
mCO2 = total CO2 emission mass over the test
interval as determined in paragraph (d)(2) of this section.
eCO2FTPFCL = the engine's FCL for CO2 over the
FTP duty cycle.

Example:

mNOx = 1.337 g
mCO2 = 18778 g
eCO2FTPFCL = 505.1 g/hp[middot]hr
[GRAPHIC] [TIFF OMITTED] TR24JA23.045

eNOx,offcycle = 0.035 g/hp[middot]hr

    (2) Compression-ignition. For engines subject to compression-
ignition standards, determine the off-cycle emission quantity for each
bin. When calculating mean bin emissions from ten engines to apply the
pass criteria for engine families in Sec.  1036.425(c), set any
negative off-cycle emissions quantity to zero before calculating mean
bin emissions.
    (i) Off-cycle emissions quantity for bin 1. The off-cycle emission
quantity for bin 1, miNOx,offcycle,bin1, is the mean
NOX mass emission rate from all test intervals associated
with bin 1 as calculated using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.046

Where:

i = an indexing variable that represents one 300 second test
interval.
N = total number of 300 second test intervals in bin 1.
mNOXtestinterval,i = total
NOX emission mass over the test interval i in bin 1 as
determined in paragraph (d)(2) of this section.
ttestinterval,i = total time of test interval
i in bin 1 as determined in paragraph (d)(1) of this section. Note
that the nominal value is 300 seconds.

Example:

N = 10114
mNOX,testinterval,1 = 0.021 g
mNOX,testinterval,2 = 0.025 g
mNOX,testinterval,3 = 0.031 g
ttestinterval,1 = 299.99 s
ttestinterval,2 = 299.98 s
ttestinterval,3 = 300.04 s
[GRAPHIC] [TIFF OMITTED] TR24JA23.047

miNOoffcycle,bin1, = 0.000285 g/s = 1.026 g/hr

    (ii) Off-cycle emissions quantity for bin 2. The off-cycle emission
quantity for bin 2, e[emission],offcycle,bin2, is the value
for CO2-specific emission mass for a given pollutant of all
the 300 second test intervals in bin 2 combined and converted to a
brake-specific value, as calculated for each measured pollutant using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.048

Where:

i = an indexing variable that represents one 300 second test
interval.
N = total number of 300 second test intervals in bin 2.
m[emission],testinterval,i = total emission
mass for a given pollutant over the test interval i in bin 2 as
determined in paragraph (d)(2) of this section.
mCOX,testinterval,i = total
CO2 emission mass over the test interval i in bin 2 as
determined in paragraph (d)(2) of this section.
eCO2FTPFCL = the engine's FCL for CO2 over the
FTP duty cycle.

Example:

N = 15439
mNOX1 = 0.546 g
mNOX2 = 0.549 g
mNOX3 = 0.556 g
mCOX1 = 10950.2 g
mCOX2 = 10961.3 g
mCOX3 = 10965.3 g
eCOX FTPFCL = 428.1 g/hp[middot]hr

[GRAPHIC] [TIFF OMITTED] TR24JA23.049

    eNOX,offcycle,bin2 = 0.026 g/hp[middot]hr

    (h) Shift-day ambient temperature. For engines subject to
compression-ignition standards, determine the mean shift-day ambient
temperature, Tiamb, considering only temperature readings
corresponding to data with no exclusions under paragraph (c)(3) of this
section.
    (i) Graphical illustration. Figure 1 of this section illustrates a
test interval with interruptions of one or more data points excluded
under paragraph (c)(3) of this section. The x-axis is time and the y-
axis is the mass emission rate at each data point, m(t) The data points
coincident with any exclusion are illustrated with open circles. The
shaded area corresponding to each group of closed circles represents
the total emission mass over that test subinterval. Note that negative
values of m(t) are retained and not set to zero in the numerical
integration calculation. The first group of data points without any
exclusions is referred to as the first test subinterval and so on.

Figure 1 to Paragraph (i) of Sec.  1036.530--Illustration of
Integration of Mass of Emissions Over a Test Interval With Exclude Data
Points
[GRAPHIC] [TIFF OMITTED] TR24JA23.050

Sec.  1036.535  Determining steady-state engine fuel maps and fuel
consumption at idle.

    The procedures in this section describe how to determine an
engine's steady-state fuel map and fuel consumption at idle for model
year 2021 and later vehicles; these procedures apply as described in
Sec.  1036.505. Vehicle manufacturers may need these values to
demonstrate compliance with emission standards under 40 CFR part 1037.
    (a) General test provisions. Perform fuel mapping using the
procedure described in paragraph (b) of this section to establish
measured fuel-consumption rates at a range of engine speed and load
settings. Measure fuel consumption at idle using the procedure
described in paragraph (c) of this section. Paragraph (d) of this
section describes how to apply the steady-state mapping from paragraph
(b) of this section for the special case of cycle-average mapping for
highway cruise cycles as described in Sec.  1036.540. Use these
measured fuel-consumption values to declare fuel-consumption rates for
certification as described in paragraph (g) of this section.
    (1) Map the engine's torque curve and declare engine idle speed as
described in Sec.  1036.505(c)(1) and (3). Perform emission
measurements as described in 40 CFR 1065.501 and 1065.530 for discrete-
mode steady-state testing. This section uses engine parameters and
variables that are consistent with 40 CFR part 1065.
    (2) Measure NOX emissions as described in paragraph (f)
of this section. Include these measured NOX values any time
you report to us your fuel consumption values from testing under this
section.
    (3) You may use shared data across engine configurations to the
extent that the fuel-consumption rates remain valid.
    (4) The provisions related to carbon balance error verification in
Sec.  1036.543 apply for all testing in this section. These procedures
are optional, but we will perform carbon balance error verification for
all testing under this section.
    (5) Correct fuel mass flow rate to a mass-specific net energy
content of a reference fuel as described in paragraph (e) of this
section.
    (b) Steady-state fuel mapping. Determine steady-state fuel-
consumption rates for each engine configuration over a series of paired
engine speed and torque setpoints as described in this paragraph (b).
For example, if you test a high-output (parent) configuration and
create a different (child) configuration that uses the same fueling
strategy but limits the engine operation to be a subset of that from
the high-output configuration, you may use the fuel-consumption rates
for the reduced number of mapped points for the low-output
configuration, as long as the narrower map includes at least 70 points.
Perform fuel mapping as follows:
    (1) Generate the fuel-mapping sequence of engine speed and torque
setpoints as follows:
    (i) Select the following required speed setpoints: warm idle speed,
fnidle the highest speed above maximum power at which 70% of
maximum power occurs, nhi, and eight (or more) equally
spaced points between fnidle and nhi. (See 40 CFR
1065.610(c)). For engines with adjustable warm idle speed, replace
fnidle with minimum warm idle speed fnidlemin.
    (ii) Determine the following default torque setpoints at each of
the selected

speed setpoints: zero (T = 0), maximum mapped torque,
Tmax mapped, and eight (or more) equally spaced points
between T = 0 and Tmax mapped. Select the maximum torque
setpoint at each speed to conform to the torque map as follows:
    (A) Calculate 5 percent of Tmax mapped. Subtract this
result from the mapped torque at each speed setpoint, Tmax.
    (B) Select Tmax at each speed setpoint as a single
torque value to represent all the default torque setpoints above the
value determined in paragraph (b)(1)(ii)(A) of this section. All the
default torque setpoints less than Tmax at a given speed
setpoint are required torque setpoints.
    (iii) You may select any additional speed and torque setpoints
consistent with good engineering judgment. For example you may need to
select additional points if the engine's fuel consumption is nonlinear
across the torque map. Avoid creating a problem with interpolation
between narrowly spaced speed and torque setpoints near
Tmax. For each additional speed setpoint, we recommend
including a torque setpoint of Tmax; however, you may select
torque setpoints that properly represent in-use operation. Increments
for torque setpoints between these minimum and maximum values at an
additional speed setpoint must be no more than one-ninth of
Tmax,mapped. Note that if the test points were added for the
child rating, they should still be reported in the parent fuel map. We
will test with at least as many points as you. If you add test points
to meet testing requirements for child ratings, include those same test
points as reported values for the parent fuel map. For our testing, we
will use the same normalized speed and torque test points you use, and
we may select additional test points.
    (iv) Start fuel-map testing at the highest speed setpoint and
highest torque setpoint, followed by decreasing torque setpoints at the
highest speed setpoint. Continue testing at the next lowest speed
setpoint and the highest torque setpoint at that speed setpoint,
followed by decreasing torque setpoints at that speed setpoint. Follow
this pattern through all the speed and torque points, ending with the
lowest speed (fnidle or fnidlemin) and torque
setpoint (T = 0). The following figure illustrates an array of test
points and the corresponding run order.

Figure 1 to Paragraph (b)(1)(iv) of Sec.  1036.535--Illustration of
Steady-State Fuel-Mapping Test Points and Run Order
[GRAPHIC] [TIFF OMITTED] TR24JA23.051

    (v) The highest torque setpoint for each speed setpoint is an
optional reentry point to restart fuel mapping after an incomplete test
run.
    (vi) The lowest torque setpoint at each speed setpoint is an
optional exit point to interrupt testing. Paragraph (b)(7) of this
section describes how to interrupt testing at other times.
    (2) If the engine's warm idle speed is adjustable, set it to its
minimum value, fnidlemin.
    (3) The measurement at each unique combination of speed and torque
setpoints constitutes a test interval. Unless we specify otherwise, you
may program the dynamometer to control either speed or torque for a
given test interval, with operator demand controlling the other
parameter. Control speed and torque so that all recorded speed points
are within 1% of nhi from the target speed and
all recorded engine

torque points are within 5% of Tmax mapped from
the target torque during each test interval, except as follows:
    (i) For steady-state engine operating points that cannot be
achieved, and the operator demand stabilizes at minimum; program the
dynamometer to control torque and let the engine govern speed (see 40
CFR 1065.512(b)(1)). Control torque so that all recorded engine torque
points are within 25 N[middot]m from the target torque. The
specified speed tolerance does not apply for the test interval.
    (ii) For steady-state engine operating points that cannot be
achieved and the operator demand stabilizes at maximum and the speed
setpoint is below 90% of nhi even with maximum operator
demand, program the dynamometer to control speed and let the engine
govern torque (see 40 CFR 1065.512(b)(2)). The specified torque
tolerance does not apply for the test interval.
    (iii) For steady-state engine operating points that cannot be
achieved and the operator demand stabilizes at maximum and the speed
setpoint is at or above 90% of nhi even with maximum
operator demand, program the dynamometer to control torque and let the
engine govern speed (see 40 CFR 1065.512(b)(1)). The specified speed
tolerance does not apply for the test interval.
    (iv) For the steady-state engine operating points at the minimum
speed setpoint and maximum torque setpoint, you may program the
dynamometer to control speed and let the engine govern torque. The
specified torque tolerance does not apply for this test interval if
operator demand stabilizes at its maximum or minimum limit.
    (4) Record measurements using direct and/or indirect measurement of
fuel flow as follows:
    (i) Direct fuel-flow measurement. Record speed and torque and
measure fuel consumption with a fuel flow meter for (30  1)
seconds. Determine the corresponding mean values for the test interval.
Use of redundant direct fuel-flow measurements requires our advance
approval.
    (ii) Indirect fuel-flow measurement. Record speed and torque and
measure emissions and other inputs needed to run the chemical balance
in 40 CFR 1065.655(c) for (30  1) seconds. Determine the
corresponding mean values for the test interval. Use of redundant
indirect fuel-flow measurements requires our advance approval. Measure
background concentration as described in 40 CFR 1065.140, except that
you may use one of the following methods to apply a single background
reading to multiple test intervals:
    (A) For batch sampling, you may sample periodically into the bag
over the course of multiple test intervals and read them as allowed in
paragraph (b)(7)(i) of this section. You must determine a single
background reading for all affected test intervals if you use the
method described in this paragraph (b)(4)(ii)(A).
    (B) You may measure background concentration by sampling from the
dilution air during the interruptions allowed in paragraph (b)(7)(i) of
this section or at other times before or after test intervals. Measure
background concentration within 30 minutes before the first test
interval and within 30 minutes before each reentry point. Measure the
corresponding background concentration within 30 minutes after each
exit point and within 30 minutes after the final test interval. You may
measure background concentration more frequently. Correct measured
emissions for test intervals between a pair of background readings
based on the average of those two values. Once the system stabilizes,
collect a background sample over an averaging period of at least 30
seconds.
    (5) Warm up the engine as described in 40 CFR 1065.510(b)(2).
Within 60 seconds after concluding the warm-up, linearly ramp the speed
and torque setpoints over 5 seconds to the starting test point from
paragraph (b)(1) of this section.
    (6) Stabilize the engine by operating at the specified speed and
torque setpoints for (70  1) seconds and then start the
test interval. Record measurements during the test interval. Measure
and report NOX emissions over each test interval as
described in paragraph (f) of this section.
    (7) After completing a test interval, linearly ramp the speed and
torque setpoints over 5 seconds to the next test point.
    (i) You may interrupt the fuel-mapping sequence before a reentry
point as noted in paragraphs (b)(1)(v) and (vi) of this section. If you
zero and span analyzers, read and evacuate background bag samples, or
sample dilution air for a background reading during the interruption,
the maximum time to stabilize in paragraph (b)(6) of this section does
not apply. If you shut off the engine, restart with engine warm-up as
described in paragraph (b)(5) of this section.
    (ii) You may interrupt the fuel-mapping sequence at a given speed
setpoint before completing measurements at that speed. If this happens,
you may measure background concentration and take other action as
needed to validate test intervals you completed before the most recent
reentry point. Void all test intervals after the last reentry point.
Restart testing at the appropriate reentry point in the same way that
you would start a new test. Operate the engine long enough to stabilize
aftertreatment thermal conditions, even if it takes more than 70
seconds. In the case of an infrequent regeneration event, interrupt the
fuel-mapping sequence and allow the regeneration event to finish with
the engine operating at a speed and load that allows effective
regeneration.
    (iii) If you void any one test interval, all the testing at that
speed setpoint is also void. Restart testing by repeating the fuel-
mapping sequence as described in this paragraph (b); include all voided
speed setpoints and omit testing at speed setpoints that already have a
full set of valid results.
    (8) If you determine fuel-consumption rates using emission
measurements from the raw or diluted exhaust, calculate the mean fuel
mass flow rate, mifuel, for each point in the fuel map using
the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.052

Where:

mifuel = mean fuel mass flow rate for a given fuel map
setpoint, expressed to at least the nearest 0.001 g/s.
MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of test
fuels) as determined in 40 CFR 1065.655(d), except that you may not
use the default properties in Table 2 of 40 CFR 1065.655 to
determine [alpha], [beta], and wC. You may not account
for the contribution to [alpha], [beta], [gamma], and [delta] of
diesel exhaust fluid or other non-fuel fluids injected into the
exhaust.

niexh = the mean raw exhaust molar flow rate from which
you measured emissions according to 40 CFR 1065.655.
xCcombdry = the mean concentration of carbon from fuel
and any injected fluids in the exhaust per mole of dry exhaust as
determined in 40 CFR 1065.655(c).
xH2Oexhdry = the mean concentration of H2O in
exhaust per mole of dry exhaust as determined in 40 CFR 1065.655(c).
miCO2DEF = the mean CO2 mass emission rate
resulting from diesel exhaust fluid decomposition as determined in
paragraph (b)(9) of this section. If your engine does not use diesel
exhaust fluid, or if you choose not to perform this correction, set
miCO2DEF equal to 0.
MCO2 = molar mass of carbon dioxide.

Example:

MC = 12.0107 g/mol
wCmeas = 0.869
niexh = 25.534 mol/s
xCcombdry = 0.002805 mol/mol
xH2Oexhdry = 0.0353 mol/mol
miCO2DEF = 0.0726 g/s
MCO2 = 44.0095 g/mol
[GRAPHIC] [TIFF OMITTED] TR24JA23.053

mifuel = 0.933 g/s

    (9) If you determine fuel-consumption rates using emission
measurements with engines that utilize diesel exhaust fluid for
NOX control and you correct for the mean CO2 mass
emission rate resulting from diesel exhaust fluid decomposition as
described in paragraph (b)(8) of this section, perform this correction
at each fuel map setpoint using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.054

Where:

miDEF = the mean mass flow rate of injected urea solution
diesel exhaust fluid for a given sampling period, determined
directly from the ECM, or measured separately, consistent with good
engineering judgment.
MCO2 = molar mass of carbon dioxide.
wCH4N2O = mass fraction of urea in diesel exhaust fluid
aqueous solution. Note that the subscript ``CH4N2O'' refers to urea
as a pure compound and the subscript ``DEF'' refers to the aqueous
urea diesel exhaust fluid as a solution of urea in water. You may
use a default value of 32.5% or use good engineering judgment to
determine this value based on measurement.
MCH4N2O = molar mass of urea.

Example:

miDEF = 0.304 g/s
MCO2 = 44.0095 g/mol
wCH4N2O = 32.5% = 0.325
MCH4N2O = 60.05526 g/mol
[GRAPHIC] [TIFF OMITTED] TR24JA23.055

miCO2DEF = 0.0726 g/s

    (10) Correct the measured or calculated mean fuel mass flow rate,
at each of the engine-idle operating points to account for mass-
specific net energy content as described in paragraph (e) of this
section.
    (c) Fuel consumption at idle. Determine fuel-consumption rates at
idle for each engine configuration that is certified for installation
in vocational vehicles. Determine fuel-consumption rates at idle by
testing engines over a series of paired engine speed and torque
setpoints as described in this paragraph (c). Perform measurements as
follows:
    (1) The idle test sequence consists of measuring fuel consumption
at four test points representing each combination of the following
speed and torque setpoints in any order.
    (i) Speed setpoints for engines with adjustable warm idle speed are
minimum warm idle speed, fnidlemin, and maximum warm idle
speed, fnidlemax. Speed setpoints for engines with no
adjustable warm idle speed (with zero torque on the primary output
shaft) are fnidle and 1.15 times fnidle.
    (ii) Torque setpoints are 0 and 100 N[middot]m.
    (2) Control speed and torque as follows:
    (i) Adjustable warm idle speed. Set the engine's warm idle speed to
the next speed setpoint any time before the engine reaches the next
test point. Control both speed and torque when the engine is warming up
and when it is transitioning to the next test point. Start to control
both speed and torque. At any time prior to reaching the next engine-
idle operating point, set the engine's adjustable warm idle speed
setpoint to the speed setpoint of the next engine-idle operating point
in the sequence. This may be done before or during the warm-up or
during the transition. Near the end of the transition period control
speed and torque as described in paragraph (b)(3)(i) of this section
shortly before reaching each test point. Once the engine is operating
at the desired speed and torque setpoints, set the operator demand to
minimum; control torque so that all recorded engine torque points are
within 25 N[middot]m from the target torque.
    (ii) Nonadjustable warm idle speed. For the lowest speed setpoint,
control speed and torque as described in paragraph (c)(2)(i) of this
section, except for adjusting the warm idle speed. For the second-
lowest speed setpoint, control speed and torque so that all recorded
speed points are within 1% of nhi from the
target speed and engine torque within 5% of
Tmax mapped from the target torque.
    (3) Record measurements using direct and/or indirect measurement of
fuel flow as follows:
    (i) Direct fuel flow measurement. Record speed and torque and
measure fuel consumption with a fuel flow meter for (600 1)
seconds. Determine the corresponding mean values for the test interval.
Use of redundant direct fuel-flow measurements require prior EPA
approval.

    (ii) Indirect fuel flow measurement. Record speed and torque and
measure emissions and other inputs needed to run the chemical balance
in 40 CFR 1065.655(c) for (600 1) seconds. Determine the
corresponding mean values for the test interval. Use of redundant
indirect fuel-flow measurements require prior EPA approval. Measure
background concentration as described in paragraph (b)(4)(ii) of this
section. We recommend setting the CVS flow rate as low as possible to
minimize background, but without introducing errors related to
insufficient mixing or other operational considerations. Note that for
this testing 40 CFR 1065.140(e) does not apply, including the minimum
dilution ratio of 2:1 in the primary dilution stage.
    (4) Warm up the engine as described in 40 CFR 1065.510(b)(2).
Within 60 seconds after concluding the warm-up, linearly ramp the speed
and torque over 20 seconds to the first speed and torque setpoint.
    (5) The measurement at each unique combination of speed and torque
setpoints constitutes a test interval. Operate the engine at the
selected speed and torque set points for (180 1) seconds,
and then start the test interval. Record measurements during the test
interval. Measure and report NOX emissions over each test
interval as described in paragraph (f) of this section.
    (6) After completing each test interval, repeat the steps in
paragraphs (c)(4) and (5) of this section for all the remaining engine-
idle test points.
    (7) Each test point represents a stand-alone measurement. You may
therefore take any appropriate steps between test intervals to process
collected data and to prepare engines and equipment for further
testing. Note that the allowances for combining background in paragraph
(b)(4)(ii)(B) of this section do not apply. If an infrequent
regeneration event occurs, allow the regeneration event to finish; void
the test interval if the regeneration starts during a measurement.
    (8) Correct the measured or calculated mean fuel mass flow rate, at
each of the engine-idle operating points to account for mass-specific
net energy content as described in paragraph (e) of this section.
    (d) Steady-state fuel maps used for cycle-average fuel mapping of
the highway cruise cycles. Determine steady-state fuel-consumption
rates for each engine configuration over a series of paired engine
speed and torque setpoints near idle as described in this paragraph
(d). Perform fuel mapping as described in paragraph (b) of this section
with the following exceptions:
    (1) Select speed setpoints to cover a range of values to represent
in-use operation at idle. Speed setpoints for engines with adjustable
warm idle speed must include at least minimum warm idle speed,
fnidlemin, and a speed at or above maximum warm idle speed,
fnidlemax. Speed setpoints for engines with no adjustable
idle speed must include at least warm idle speed (with zero torque on
the primary output shaft), fnidle, and a speed at or above
1.15 [middot] fnidle.
    (2) Select the following torque setpoints at each speed setpoint to
cover a range of values to represent in-use operation at idle:
    (i) The minimum torque setpoint is zero.
    (ii) Choose a maximum torque setpoint that is at least as large as
the value determined by the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.056

Where:

Tfnstall = the maximum engine torque at
fnstall.
fnidle = for engines with an adjustable warm idle speed,
use the maximum warm idle speed, fnidlemax. For engines
without an adjustable warm idle speed, use warm idle speed,
fnidle.
fnstall = the stall speed of the torque converter; use
fntest or 2250 r/min, whichever is lower.
Pacc = accessory power for the vehicle class; use 1500 W
for Vocational Light HDV, 2500 W for Vocational Medium HDV, and 3500
W for Tractors and Vocational Heavy HDV. If your engine is going to
be installed in multiple vehicle classes, perform the test with the
accessory power for the largest vehicle class the engine will be
installed in.

Example:

Tfnstall = 1870 N[middot]m
fntest = 1740.8 r/min = 182.30 rad/s
fnstall = 1740.8 r/min = 182.30 rad/s
fnidle = 700 r/min = 73.30 rad/s
Pacc = 1500 W
[GRAPHIC] [TIFF OMITTED] TR24JA23.057

Tidlemaxest = 355.07 N[middot]m

    (iii) Select one or more equally spaced intermediate torque
setpoints, as needed, such that the increment between torque setpoints
is no greater than one-ninth of Tmax,mapped.
    (e) Correction for net energy content. Correct the measured or
calculated mean fuel mass flow rate, , for each test interval to a
mass-specific net energy content of a reference fuel using the
following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.058

Where:

Emfuelmeas = the mass-specific net energy content of the
test fuel as determined in Sec.  1036.550(b)(1).
EmfuelCref = the reference value of carbon-mass-specific
net energy content for the appropriate fuel. Use the values shown in
Table 1 in Sec.  1036.550 for the designated fuel types, or values
we approve for other fuel types.
wCref = the reference value of carbon mass fraction for
the test fuel as shown in Table 1 of Sec.  1036.550 for the
designated fuels. For any fuel not identified in the table, use the
reference carbon mass fraction of diesel fuel for engines subject to
compression-ignition standards, and use the reference carbon mass
fraction of gasoline for engines subject to spark-ignition
standards.

Example:

mifuel = 0.933 g/s
Emfuelmeas = 42.7984 MJ/kgC
EmfuelCref = 49.3112 MJ/kgC

wCref = 0.874
[GRAPHIC] [TIFF OMITTED] TR24JA23.059

mifuel = 0.927 g/s

    (f) Measuring NOX emissions. Measure NOX emissions for
each sampling period in g/s. You may perform these measurements using a
NOX emission-measurement system that meets the requirements
of 40 CFR part 1065, subpart J. If a system malfunction prevents you
from measuring NOX emissions during a test under this
section but the test otherwise gives valid results, you may consider
this a valid test and omit the NOX emission measurements;
however, we may require you to repeat the test if we determine that you
inappropriately voided the test with respect to NOX emission
measurement.
    (g) Measured vs. declared fuel consumption. Determine declared fuel
consumption as follows:
    (1) Select fuel consumption rates in g/s to characterize the
engine's fuel maps. You must select a declared value for each test
point that is at or above the corresponding value determined in
paragraphs (b) through (d) of this section, including those from
redundant measurements.
    (2) Declared fuel consumption serves as emission standards under
Sec.  1036.108. These are the values that vehicle manufacturers will
use for certification under 40 CFR part 1037. Note that production
engines are subject to GEM cycle-weighted limits as described in Sec.
1036.301.
    (3) If you perform the carbon balance error verification, select
declared values that are at or above the following emission
measurements:
    (i) If you pass the [epsi]rC verification, you may use
the average of the values from direct and indirect fuel measurements.
    (ii) If you fail [epsi]rC verification, but pass either
the [epsi]aC or [epsi]aCrate verification, use
the value from indirect fuel measurement.
    (iii) If you fail all three verifications, you must either void the
test interval or use the highest value from direct and indirect fuel
measurements. Note that we will consider our test results to be invalid
if we fail all three verifications.

Sec.  1036.540  Determining cycle-average engine fuel maps.

    (a) Overview. This section describes how to determine an engine's
cycle-average fuel maps for model year 2021 and later vehicles. Vehicle
manufacturers may need cycle-average fuel maps for transient duty
cycles, highway cruise cycles, or both to demonstrate compliance with
emission standards under 40 CFR part 1037. Generate cycle-average
engine fuel maps as follows:
    (1) Determine the engine's torque maps as described in Sec.
1036.505(c).
    (2) Determine the engine's steady-state fuel map and fuel
consumption at idle as described in Sec.  1036.535. If you are applying
cycle-average fuel mapping for highway cruise cycles, you may instead
use GEM's default fuel map instead of generating the steady-state fuel
map in Sec.  1036.535(b).
    (3) Simulate several different vehicle configurations using GEM
(see 40 CFR 1037.520) to create new engine duty cycles as described in
paragraph (c) of this section. The transient vehicle duty cycles for
this simulation are in 40 CFR part 1037, appendix A; the highway cruise
cycles with grade are in 40 CFR part 1037, appendix D. Note that GEM
simulation relies on vehicle service classes as described in 40 CFR
1037.140.
    (4) Test the engines using the new duty cycles to determine fuel
consumption, cycle work, and average vehicle speed as described in
paragraph (d) of this section and establish GEM inputs for those
parameters for further vehicle simulations as described in paragraph
(e) of this section.
    (b) General test provisions. The following provisions apply for
testing under this section:
    (1) To perform fuel mapping under this section for hybrid engines,
make sure the engine and its hybrid features are appropriately
configured to represent the hybrid features in your testing.
    (2) Measure NOX emissions for each specified sampling
period in grams. You may perform these measurements using a
NOX emission-measurement system that meets the requirements
of 40 CFR part 1065, subpart J. Include these measured NOX
values any time you report to us your fuel-consumption values from
testing under this section. If a system malfunction prevents you from
measuring NOX emissions during a test under this section but
the test otherwise gives valid results, you may consider this a valid
test and omit the NOX emission measurements; however, we may
require you to repeat the test if we determine that you inappropriately
voided the test with respect to NOX emission measurement.
    (3) The provisions related to carbon balance error verification in
Sec.  1036.543 apply for all testing in this section. These procedures
are optional, but we will perform carbon balance error verification for
all testing under this section.
    (4) Correct fuel mass to a mass-specific net energy content of a
reference fuel as described in paragraph (d)(13) of this section.
    (5) This section uses engine parameters and variables that are
consistent with 40 CFR part 1065.
    (c) Create engine duty cycles. Use GEM to simulate your engine
operation with several different vehicle configurations to create
transient and highway cruise engine duty cycles corresponding to each
vehicle configuration as follows:
    (1) Set up GEM to simulate your engine's operation based on your
engine's torque maps, steady-state fuel maps, warm-idle speed as
defined in 40 CFR 1037.520(h)(1), and fuel consumption at idle as
described in paragraphs (a)(1) and (2) of this section.
    (2) Set up GEM with transmission parameters for different vehicle
service classes and vehicle duty cycles. Specify the transmission's
torque limit for each gear as the engine's maximum torque as determined
in 40 CFR 1065.510. Specify the transmission type as Automatic
Transmission for all engines and for all engine and vehicle duty
cycles, except that the transmission type is Automated Manual
Transmission for Heavy HDE operating over the highway cruise cycles or
the SET duty cycle. For automatic transmissions set neutral idle to
``Y'' in the vehicle file. Select gear ratios for each gear as shown in
the following table:

                    Table 1 to Paragraph (c)(2) of Sec.   1036.540--GEM Input for Gear Ratio
----------------------------------------------------------------------------------------------------------------
                                                 Spark-ignition HDE,
                                                light HDE, and medium        Heavy HDE--      Heavy HDE-- cruise
                 Gear number                     HDE-- all engine and     transient and FTP      and SET duty
                                                 vehicle duty cycles         duty cycles            cycles
----------------------------------------------------------------------------------------------------------------
1............................................                     3.10                  3.51                12.8
2............................................                     1.81                  1.91                9.25

3............................................                     1.41                  1.43                6.76
4............................................                     1.00                  1.00                4.90
5............................................                     0.71                  0.74                3.58
6............................................                     0.61                  0.64                2.61
7............................................  .......................  ....................                1.89
8............................................  .......................  ....................                1.38
9............................................  .......................  ....................                1.00
10...........................................  .......................  ....................                0.73
Lockup Gear..................................                        3                     3  ..................
----------------------------------------------------------------------------------------------------------------

    (3) Run GEM for each simulated vehicle configuration and use the
GEM outputs of instantaneous engine speed and engine flywheel torque
for each vehicle configuration to generate a 10 Hz transient duty cycle
corresponding to each vehicle configuration operating over each vehicle
duty cycle. Run GEM for the specified number of vehicle configurations.
You may run additional vehicle configurations to represent a wider
range of in-use vehicles. Run GEM as follows:
    (i) Determining axle ratio and tire size. Set the axle ratio,
ka, and tire size,
[GRAPHIC] [TIFF OMITTED] TR24JA23.060

    for each vehicle configuration based on the corresponding
designated engine speed (fnrefA, fnrefB,
fnrefC, fnrefD, or fntest as defined
in 40 CFR 1065.610(c)(2)) at 65 mi/hr for the transient duty cycle and
for the 65 mi/hr highway cruise cycle. Similarly, set these parameters
based on the corresponding designated engine speed at 55 mi/hr for the
55 mi/hr highway cruise cycle. Use one of the following equations to
determine
[GRAPHIC] [TIFF OMITTED] TR24JA23.061

and ka at each of the defined engine speeds:
[GRAPHIC] [TIFF OMITTED] TR24JA23.062

Where:

fn[speed] = engine's angular speed as determined in
paragraph (c)(3)(ii) or (iii) of this section.
ktopgear = transmission gear ratio in the highest
available gear from Table 1 of this section.
vref = reference speed. Use 65 mi/hr for the transient
cycle and the 65 mi/hr highway cruise cycle and use 55 mi/hr for the
55 mi/hr highway cruise cycle.
[GRAPHIC] [TIFF OMITTED] TR24JA23.063

Example for a vocational Light HDV or vocational Medium HDV with a 6-
speed automatic transmission at B speed (Test 3 or 4 in Table 3 of this
section):

fnrefB = 1870 r/min = 31.17 r/s
kaB = 4.0
ktopgear = 0.61
vref = 65 mi/hr = 29.06 m/s

[GRAPHIC] [TIFF OMITTED] TR24JA23.064

    (ii) Vehicle configurations for Spark-ignition HDE, Light HDE, and
Medium HDE. Test at least eight different vehicle configurations for
engines that will be installed in vocational Light HDV or vocational
Medium HDV using vehicles in the following table:
[GRAPHIC] [TIFF OMITTED] TR24JA23.065

    (iii) Vehicle configurations for Heavy HDE. Test at least nine
different vehicle configurations for engines that will be installed in
vocational Heavy HDV and for tractors that are not heavy-haul tractors.
Test six different vehicle configurations for engines that will be
installed in heavy-haul tractors. Use the settings specific to each
vehicle configuration as shown in Table 3 or Table 4 in this section,
as appropriate. Engines subject to testing under both Table 3 and Table
4 in this section need not repeat overlapping vehicle configurations,
so complete fuel mapping requires testing 12 (not 15) vehicle
configurations for those engines. However, the preceding sentence does
not apply if you choose to create two separate maps from the vehicle
configurations defined in Table 3 and Table 4 in this section. Tables 3
and 4 follow:

[GRAPHIC] [TIFF OMITTED] TR24JA23.066

    (iv) Vehicle configurations for mixed-use engines. If the engine
will be installed in a combination of vehicles defined in paragraphs
(c)(3)(ii) and (iii) of this section, use good engineering judgment to
select at least nine vehicle configurations from Table 2 and Table 3 in
this section that best represent the range of vehicles your engine will
be sold in. This may require you to define additional representative
vehicle configurations. For example, if your engines will be installed
in vocational Medium HDV and vocational Heavy HDV, you might select
Tests 2, 4, 6 and 8 of Table 2 in this section to represent vocational
Medium HDV and Tests 3, 6, and 9 of Table 3 in this section to
represent vocational Heavy HDV and add two more vehicle configurations
that you define.
    (v) Defining GEM inputs. Use the defined values in Tables 1 through
4 in this section to set up GEM with the correct regulatory subcategory
and vehicle weight reduction.
    (d) Test the engine with GEM cycles. Test the engine over each of
the transient engine duty cycles generated in paragraph (c) of this
section as follows:
    (1) Operate the engine over a sequence of required and optional
engine duty cycles as follows:
    (i) Sort the list of engine duty cycles into three separate groups
by vehicle duty cycle: transient vehicle cycle, 55 mi/hr highway cruise
cycle, and 65 mi/hr highway cruise cycle.
    (ii) Within each group of engine duty cycles derived from the same
vehicle duty cycle, first run the engine duty cycle with the highest
reference cycle work, followed by the cycle with the lowest cycle work;
followed by the cycle with second-highest cycle work, followed by the
cycle with the second-lowest cycle work; continuing through all the
cycles for that vehicle duty cycle. The series of engine duty cycles to
represent a single vehicle duty cycle is a single fuel-mapping
sequence. Each engine duty cycle represents a different interval.
Repeat the fuel-mapping sequence for the engine duty cycles derived
from the other vehicle duty cycles until testing is complete.
    (iii) Operate the engine over two full engine duty cycles to
precondition before each interval in the fuel-mapping sequence.
Precondition the engine before the first and second engine duty cycle
in each fuel-mapping sequence by repeating operation with the engine
duty cycle with the highest reference cycle work over the relevant
vehicle duty cycle. The preconditioning for the remaining cycles in the
fuel-mapping sequence consists of operation over the preceding two
engine duty cycles in the fuel-mapping sequence (with or without
measurement). For transient vehicle duty cycles, start each engine duty
cycle within 10 seconds after finishing the preceding engine duty cycle
(with or without measurement). For highway cruise cycles, start each
engine duty cycle and interval after linearly ramping to the speed and
torque setpoints over 5 seconds and stabilizing for 15 seconds.
    (2) If the engine has an adjustable warm idle speed setpoint, set
it to the value defined in 40 CFR 1037.520(h)(1).
    (3) Control speed and torque to meet the cycle validation criteria
in 40 CFR 1065.514 for each interval, except that the standard error of
the estimate in Table 2 of 40 CFR 1065.514 is the only speed criterion
that applies if the range of reference speeds is less than 10 percent
of the mean reference speed. For spark-ignition gaseous-fueled engines
with fuel delivery at a single point in the intake manifold, you may
apply the statistical criteria in Table 5 in this section for transient
testing. Note that 40

CFR part 1065 does not allow reducing cycle precision to a lower
frequency than the 10 Hz reference cycle generated by GEM.

  Table 5 to Paragraph (c)(3) of Sec.   1036.540--Statistical Criteria for Validating Duty Cycles for Gaseous-
                                        Fueled Spark-Ignition Engines \a\
----------------------------------------------------------------------------------------------------------------
                Parameter                      Speed                Torque                       Power
----------------------------------------------------------------------------------------------------------------
Slope, a1...............................
Absolute value of intercept,              ..............  <=3% of maximum mapped      ..........................
 [verbar]a0[verbar].                                       torque.
Standard error of the estimate, SEE.....  ..............  <=15% of maximum mapped     <=15% of maximum mapped
                                                           torque.                     power
Coefficient of determination, r \2\.....  ..............  >=0.700...................  >=0.750
----------------------------------------------------------------------------------------------------------------
\a\ Statistical criteria apply as specified in 40 CFR 1065.514 unless otherwise specified.

    (4) Record measurements using direct and/or indirect measurement of
fuel flow as follows:
    (i) Direct fuel-flow measurement. Record speed and torque and
measure fuel consumption with a fuel flow meter for the interval
defined by the engine duty cycle. Determine the corresponding mean
values for the interval. Use of redundant direct fuel-flow measurements
requires our advance approval.
    (ii) Indirect fuel-flow measurement. Record speed and torque and
measure emissions and other inputs needed to run the chemical balance
in 40 CFR 1065.655(c) for the interval defined by the engine duty
cycle. Determine the corresponding mean values for the interval. Use of
redundant indirect fuel-flow measurements requires our advance
approval. Measure background concentration as described in 40 CFR
1065.140, except that you may use one of the following methods to apply
a single background reading to multiple intervals:
    (A) If you use batch sampling to measure background emissions, you
may sample periodically into the bag over the course of multiple
intervals. If you use this provision, you must apply the same
background readings to correct emissions from each of the applicable
intervals.
    (B) You may determine background emissions by sampling from the
dilution air over multiple engine duty cycles. If you use this
provision, you must allow sufficient time for stabilization of the
background measurement; followed by an averaging period of at least 30
seconds. Use the average of the two background readings to correct the
measurement from each engine duty cycle. The first background reading
must be taken no greater than 30 minutes before the start of the first
applicable engine duty cycle and the second background reading must be
taken no later than 30 minutes after the end of the last applicable
engine duty cycle. Background readings may not span more than a full
fuel-mapping sequence for a vehicle duty cycle.
    (5) Warm up the engine as described in 40 CFR 1065.510(b)(2).
Within 60 seconds after concluding the warm-up, start the linear ramp
of speed and torque over 20 seconds to the first speed and torque
setpoint of the preconditioning cycle.
    (6) Precondition the engine before the start of testing as
described in paragraph (d)(1)(iii) of this section.
    (7) Operate the engine over the first engine duty cycle. Record
measurements during the interval. Measure and report NOX
emissions over each interval as described in paragraph (b)(2) of this
section.
    (8) Continue testing engine duty cycles that are derived from the
other vehicle duty cycles until testing is complete.
    (9) You may interrupt the fuel-mapping sequence after completing
any interval. You may calibrate analyzers, read and evacuate background
bag samples, or sample dilution air for measuring background
concentration before restarting. Shut down the engine during any
interruption. If you restart the sequence within 30 minutes or less,
restart the sequence at paragraph (d)(6) of this section and then
restart testing at the next interval in the fuel-mapping sequence. If
you restart the sequence after more than 30 minutes, restart the
sequence at paragraph (d)(5) of this section and then restart testing
at the next interval in the fuel-mapping sequence.
    (10) The following provisions apply for infrequent regeneration
events, other interruptions during intervals, and otherwise voided
intervals:
    (i) Stop testing if an infrequent regeneration event occurs during
an interval or an interval is interrupted for any other reason. Void
the interrupted interval and any additional intervals for which you are
not able to meet requirements for measuring background concentration.
If the infrequent regeneration event occurs between intervals, void
completed intervals only if you are not able to meet requirements for
measuring background concentration for those intervals.
    (ii) If an infrequent regeneration event occurs, allow the
regeneration event to finish with the engine operating at a speed and
load that allows effective regeneration.
    (iii) If you interrupt testing during an interval, if you restart
the sequence within 30 minutes or less, restart the sequence at
paragraph (d)(6) of this section and then restart testing at the next
interval in the fuel-mapping sequence. If you restart the sequence
after more than 30 minutes, restart the sequence at paragraph (d)(5) of
this section and then restart testing at the next interval in the fuel-
mapping sequence.
    (iv) If you void one or more intervals, you must perform additional
testing to get results for all intervals. You may rerun a complete
fuel-mapping sequence or any contiguous part of the fuel-mapping
sequence. If you get a second valid measurement for any interval, use
only the result from the last valid interval. If you restart the
sequence within 30 minutes or less, restart the sequence at paragraph
(d)(6) of this section and then restart testing at the first selected
interval in the fuel-mapping sequence. If you restart the sequence
after more than 30 minutes, restart the sequence at paragraph (d)(5) of
this section and then restart testing at the first selected interval in
the fuel-mapping sequence. Continue testing until you have valid
results for all intervals. The following examples illustrate possible
scenarios for a partial run through a fuel-mapping sequence:
    (A) If you voided only the interval associated with the fourth
engine duty cycle in the sequence, you may restart the sequence using
the second and third engine duty cycles as the preconditioning cycles
and stop after completing the interval associated with the fourth
engine duty cycle.
    (B) If you voided the intervals associated with the fourth and
sixth engine duty cycles, you may restart the

sequence using the second and third engine duty cycles for
preconditioning and stop after completing the interval associated with
the sixth engine duty cycle.
    (11) You may send signals to the engine controller during the test,
such as current transmission gear and vehicle speed, if that allows
engine operation to better represent in-use operation.
    (12) Calculate the fuel mass, mfuel, for each duty cycle
using one of the following equations:
    (i) Determine fuel-consumption using emission measurements from the
raw or diluted exhaust. Calculate the mass of fuel for each duty cycle,
mfuel[cycle], as follows:
    (A) For calculations that use continuous measurement of emissions
and continuous CO2 from urea, calculate
mfuel[cycle] using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.067

Where:

MC = molar mass of carbon.
wCmeas = carbon mass fraction of fuel (or mixture of
fuels) as determined in 40 CFR 1065.655(d), except that you may not
use the default properties in Table 2 of 40 CFR 1065.655 to
determine [alpha], [beta], and wC. You may not account
for the contribution to [alpha], [beta], [gamma], and [delta] of
diesel exhaust fluid or other non-fuel fluids injected into the
exhaust.
i = an indexing variable that represents one recorded emission
value.
N = total number of measurements over the duty cycle.
nexh = exhaust molar flow rate from which you measured
emissions.
xCcombdry = amount of carbon from fuel and any injected
fluids in the exhaust per mole of dry exhaust as determined in 40
CFR 1065.655(c).
xH2Oexhdry = amount of H2O in exhaust per mole
of exhaust as determined in 40 CFR 1065.655(c).
[Delta]t = 1/frecord
MCO2 = molar mass of carbon dioxide.
mCO2DEFi = mass emission rate of CO2 resulting
from diesel exhaust fluid decomposition over the duty cycle as
determined from Sec.  1036.535(b)(9). If your engine does not
utilize diesel exhaust fluid for emission control, or if you choose
not to perform this correction, set mCO2DEFi equal to 0.

Example:

MC = 12.0107 g/mol
wCmeas = 0.867
N = 6680
nexh1= 2.876 mol/s
nexh1 = 2.224 mol/s
xCcombdry1 = 2.61[middot]10-\3\ mol/mol
xCcombdry2 = 1.91[middot]10-\3\ mol/mol
xH2Oexh1 = 3.53[middot]10-\2\ mol/mol
xH2Oexh2 = 3.13[middot]10-\2\ mol/mol
frecord = 10 Hz
[Delta]t = 1/10 = 0.1 s
MCO2 = 44.0095 g/mol
mCO2DEF1 = 0.0726 g/s
mCO2DEF2 = 0.0751 g/s
[GRAPHIC] [TIFF OMITTED] TR24JA23.068

mfueltransientTest1 = 1619.6 g

    (B) If you measure batch emissions and continuous CO2
from urea, calculate mfuel[cycle] using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.069

    (C) If you measure continuous emissions and batch CO2
from urea, calculate mfuel[cycle] using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.070

    (D) If you measure batch emissions and batch CO2 from
urea, calculate mfuel[cycle] using the following equation:
[GRAPHIC] [TIFF OMITTED] TR24JA23.071

    (ii) Manufacturers may choose to measure fuel mass flow rate.
Calculate the mass of fuel for each duty cycle,
mfuel[cycle], as follows:
[GRAPHIC] [TIFF OMITTED] TR24JA23.072

Where:

i = an indexing variable that represents one recorded value.
N = total number of measurements over the duty cycle. For batch fuel
mass measurements, set N = 1.
mfueli = the fuel mass flow rate, for each point, i,
starting from i = 1.
[Delta]t = 1/[fnof]record
[fnof]record = the data recording frequency.

Example:

N = 6680
mfuel1 = 1.856 g/s
mfuel2 = 1.962 g/s
[fnof]record = 10 Hz
[Delta]t = 1/10 = 0.1 s
mfueltransient = (1.856 + 1.962+ . . .
+mfuel6680) [middot] 0.1
mfueltransient = 111.95 g

    (13) Correct the measured or calculated fuel mass,
mfuel, for each result to a mass-specific net energy content
of a reference fuel as described in Sec.  1036.535(e), replacing
mifuel with mfuel in Eq. 1036.535-4.
    (e) Determine GEM inputs. Use the results of engine testing in
paragraph (d) of this section to determine the GEM inputs for the
transient duty cycle and optionally for each of the highway cruise
cycles corresponding to each simulated vehicle configuration as
follows:
    (1) Using the calculated fuel mass consumption values,
mfuel[cycle], described in paragraph (d) of this section,