Cause  | Correction  | ||||||||
|---|---|---|---|---|---|---|---|---|---|
Abnormalities, severe cracking, bumps, or missing areas in the accessory drive belt Abnormalities in the accessory drive system and/or components may cause engine revolutions per minute (RPM) variations and lead to a misfire diagnostic trouble code (DTC). A misfire code may be present without an actual misfire condition.  | Replace the drive belt.  | ||||||||
Worn, damaged, or mis-aligned accessory drive components or excessive pulley runout may lead to a misfire DTC. A misfire code may be present without an actual misfire condition.  | Inspect the components, and repair or replace as required.  | ||||||||
A 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.  | ||||||||
Restricted exhaust system A severe restriction in the exhaust flow can cause significant loss of engine performance and may set a DTC. Possible causes of restrictions include collapsed or dented pipes or plugged mufflers and/or catalytic converters.  | Repair or replace as required.  | ||||||||
Improperly installed or damaged vacuum hoses  | Repair or replace as required.  | ||||||||
Improper sealing between the intake manifold and cylinder heads or throttle body  | Replace the intake manifold, gaskets, cylinder heads, and/or throttle body as required.  | ||||||||
Improperly installed or damaged manifold absolute pressure (MAP) sensor The sealing grommet of the MAP sensor should not be torn or damaged.  | Repair or replace the MAP sensor as required.  | ||||||||
Damage to the MAP sensor housing  | Replace the intake manifold.  | ||||||||
Worn or loose rocker arms The rocker arm bearing end caps and/or needle bearings should be intact and in the proper position.  | Replace the valve rocker arms as required.  | ||||||||
Stuck valves Carbon buildup on the valve stem can cause the valve not to close properly.  | Repair or replace as required.  | ||||||||
Excessively worn or mis-aligned timing chain  | Replace the timing chain and sprockets as required.  | ||||||||
Worn camshaft lobes  | Replace the camshaft and valve lifters.  | ||||||||
Excessive oil pressure A lubrication system with excessive oil pressure may lead to excessive valve lifter pump up and loss of compression.  | 
 
  | ||||||||
Faulty cylinder head gaskets and/or cracking or other damage to the cylinder heads and engine block cooling system passages Coolant consumption may or may not cause the engine to overheat.  | 
 
 
  | ||||||||
Worn piston rings Oil consumption may or may not cause the engine to misfire.  | 
 
 
 
  | ||||||||
A damaged crankshaft reluctor wheel A damaged crankshaft reluctor wheel can result in different symptoms depending on the severity and location of the damage. 
 
 
  | Replace the sensor and/or crankshaft as required.  |