I have a random misfire code still after replacing a whole bunch of stuff!

Asked by Feb 24, 2017 at 01:03 PM about the 1998 GMC Sierra 1500 C1500 SLE Extended Cab SB

Question type: Maintenance & Repair

i have replaced my spider injecton, plugs and wires, distributor, cap and rotor,
new cats. the egr seems to work fine the pintle thing moves in and out pretty
good unless its not supposed to do that! the only thing i havent done is replace
coil and o2 sensors.

1 Answer


Possible causes; Faulty spark plug (s), Faulty ignition coil (s), Clogged or faulty fuel injector (s), Intake air leak, Fuel injectors harness is open or shorted, Fuel Injectors circuit poor electrical connection, Ignition coils harness is open or shorted, Ignition coils circuit poor electrical connection, Insufficient cylinders compression, Incorrect fuel pressure...Cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are common caused of multi-cylinder misfiring. If no leak are found the next step is to replace the spark plugs. If the problem persist more tests needs to be done to diagnose problem.

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