1986 Ford Bronco  I have a 1986 ford bronco 2 and I have
replaced the spark plugs and spark plug wires I have also
replaced the distributer cap and rotor bug but I still have an
engin misfire what are the signs of a bad ignition coil October
4, 2012.  As long as the wires are good and the spark plug gaps
are correct, the coil won't cause a single cylinder misfire. I'd
start with a compression test. Next, if you have multiple
injectors you might have a bad one. I don't like throwing random
parts at a problem so I'd start with a cylinder balance test to
see which cylinder is misfiring. You can do that by grounding
spark plug wires one at a time to see which one doesn't cause a
drop in rpm. Once the dead cylinder is identified, swap that
injector with one from a different cylinder to see if the
misfire goes to the other cylinder.  Oct 4, 2012.