Diagnostic Aids
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
If a fuel injector DTC is set, diagnose that DTC first.
ECM will set a DTC P0300 first, even if a specific cylinder is misfiring. If a specific cylinder misfires for a certain length of time, a specific cylinder misfire will then set.
If vehicle has had a prior replacement of a ECM or crankshaft sensor, crankshaft must be relearned. Perform CRANKSHAFT POSITION VARIATION LEARN PROCEDURE under PROGRAMMING.
Torque converter may be momentarily disabled to determine if misfire was due to a rough road (A/T).
Use scan tool to monitor MISFIRE CURRENT CYLS #1-4 while simulating different engine load conditions in the stall. Scan tool active misfire counter should pick up intermittent misfire conditions.
- Fuel injector resistance: 12-13 ohms at 74°F (23°C).
- Spark plug gap: 0.045".
- Primary ignition coil resistance: 0.4-1.6 ohms.
- Secondary ignition coil resistance (tower 1 to tower 4 or tower 2 to tower 3): 3.8-5.1k ohms.