Diagnostic Procedure
Test drive vehicle to determine which condition(s) exist when misfire occurs. Depending on the condition, test components/systems in order listed.
- Misfires only at low RPM and load:
- EGR system.
- Misfires only while accelerating:
- Ignition coil and ignition wires.
- Ignition control module (ICM).
- Misfires only at high RPM and load:
- Ignition coil and ignition wires.
- Ignition control module (ICM).
- Misfires without specific condition:
- Ignition coil and ignition wires.
- Ignition control module (ICM).
- Spark plug voltage detection system.
NOTE:
If misfire does not recur, possible causes include: fuel that does not meet owner's manual specification, lack of fuel, carbon deposits on spark plugs, etc.