Abnormalities (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. 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, repair or replace as required.

Loose or improperly installed engine flywheel or crankshaft balancer

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

Repair or replace the flywheel and/or balancer as required.

Refer to Engine Flywheel Replacement or Crankshaft Pulley Replacement .

Worn Piston Rings

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

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.