Base Engine Misfire with Abnormal Internal Lower Engine Noises

WARNING: This page is about a different car, the 2004 GMC Sierra and 2004 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.

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.	Inspect the accessory drive system components. 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.	Inspect the accessory drive system components. 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.	Inspect the crankshaft balancer. 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.	Inspect the engine flywheel. 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.	Inspect the spark plugs. Refer to Spark Plug Inspection in Engine Controls. Verify engine compression. Refer to Engine Compression Test . Inspect the cylinder bores. Inspect the pistons. Inspect the piston pins. Inspect the connecting rods. 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.	Inspect the crankshaft. Inspect the crankshaft thrust bearing. Repair or replace damaged components as required.