Operation CHARM: Car repair manuals for everyone.

Poor Performance Test


NOTE:
To prevent unnecessary diagnostic time and wrong test results, the Testing For Spark At Coil test should be performed prior to this test.


WARNING: APPLY PARKING BRAKE AND/OR BLOCK WHEELS BEFORE PERFORMING IDLE CHECK/ADJUSTMENT OR ANY TEST WITH AN OPERATING ENGINE.

PROCEDURE

Base (initial) ignition timing is not adjustable. All ignition timing functions are controlled by the PCM. See Computers and Control Systems.

Using a Scan Tool check for over-advanced or retarded spark timing.