Base Engine Misfire with Abnormal Internal Lower Engine Noises

WARNING: This page is about a different variant/trim than selected.

Cause	Correction
Review the system operation in order to familiarize yourself with the system functions. As required, disable the auto-stop function prior to repair. Refer to Hybrid Modes of Operation Description .
Abnormalities, such as severe cracking, bumps or missing areas in the accessory drive belt Abnormalities in the accessory drive system and/or components may cause engine RPM variations, noises similar to a faulty lower engine and also lead to a misfire condition. A misfire code may be present without an actual misfire condition.	Replace the drive belt, as required. Refer to Drive Belt Replacement .
Worn, damaged, or mis-aligned accessory drive components or excessive pulley runout A misfire code may be present without an actual misfire condition.	Inspect the components and repair or replace, as required.
Loose or improperly installed engine flex plate or crankshaft balancer A misfire code may be present without an actual misfire condition.	Repair or replace the flex plate and/or balancer, as required. Refer to Automatic Transmission Flex Plate Replacement , or Crankshaft Balancer Replacement .
Worn piston rings Oil consumption may or may not cause the engine to misfire.	Inspect the spark plugs for oil deposits. Refer to Spark Plug Inspection . Inspect the cylinders for a loss of compression. Refer to Engine Compression Test . Perform cylinder leak down and compression testing to determine the cause. Refer to Cylinder Leakage Test . Repair or replace, as required.
Worn crankshaft thrust bearings Severely worn thrust surfaces on the crankshaft and/or thrust bearing may permit fore and aft movement of the crankshaft and create a DTC without an actual misfire condition.	Replace the crankshaft and bearings, as required.