GM Service Manual Online
For 1990-2009 cars only

Cause

Correction

Worn, damaged, or improperly installed accessory drive belt - severe cracking, bumps or missing segments

A misfire DTC may be present without an actual misfire condition.

    â€¢ Inspect the accessory drive system components.
    â€¢ Repair or replace damaged components as required. Refer to Drive Belt Replacement .

Worn, damaged, or improperly installed accessory drive system components

A misfire DTC may be present without an actual misfire condition.

    â€¢ Inspect the accessory drive system components.
    â€¢ Repair or replace damaged components as required.

Worn, damaged, improperly installed or loose crankshaft balancer

A misfire code may be present without an actual misfire condition.

    â€¢ Inspect the crankshaft balancer.
    â€¢ Repair or replace damaged components as required. Refer to Crankshaft Balancer Replacement .

Worn, damaged, improperly installed or loose engine flywheel

A misfire code may be present without an actual misfire condition.

    â€¢ Inspect the engine flywheel.
    â€¢ Repair or replace damaged components as required. Refer to Engine Flywheel Replacement .

Worn, damaged or improperly installed piston

Pistons must be installed with the mark, or dimple, on the top of the piston, facing the front of the engine; piston pins must be centered in the connecting rod pin bore.

Oil consumption may or may not cause the engine to misfire.

    â€¢ Inspect the spark plugs. Refer to Spark Plug Inspection .
    â€¢ Verify engine compression. Refer to Engine Compression Test .
    â€¢ Inspect the cylinder bores.
    â€¢ Inspect the pistons.
    â€¢ Inspect the piston pins.
    â€¢ Inspect the connecting rods.
    â€¢ Repair or replace damaged components as required.

Worn, damaged or improperly installed crankshaft thrust bearing

A misfire code may be present without an actual misfire condition.

    â€¢ Inspect the crankshaft.
    â€¢ Inspect the crankshaft thrust bearing.
    â€¢ Repair or replace damaged components as required.