Cause | Correction | ||||||||
|---|---|---|---|---|---|---|---|---|---|
Abnormalities, extreme cracking, bumps, or missing areas, in the accessory drive belt. Abnormalities in the accessory drive system and/or components may cause engine RPM variations and lead to a misfire DTC. 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 pulley runout above acceptable tolerances may lead to a misfire DTC. A misfire code may be present without an actual misfire condition. | Inspect the components: Repair or replace as required. | ||||||||
Loose or incorrectly 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 Replacementt or Crankshaft Balancer Replacement. | ||||||||
Restricted exhaust system. An extreme 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. Refer to engine exhaust for the required procedure. | ||||||||
Incorrectly installed or damaged vacuum hoses. | Repair or replace as required. | ||||||||
Incorrect sealing between the intake manifold and cylinder heads, intake manifold and throttle body and/or pressure relief valve and intake manifold. | Replace the intake manifold, plenum duct, cylinder heads, throttle body, pressure relief valve or gaskets as required. | ||||||||
Incorrectly installed or damaged EVAP purge solenoid and/or O-ring seal. | Repair or replace the EVAP purge solenoid as required. | ||||||||
Worn or loose Stationary Hydraulic Lash Adjusters (SHLAs), valve rocker arms. The stationary hydraulic lash adjusters (SHLAs), valve rocker arm, roller bearing should be intact and in the correct position | Replace the SHLAs, valve rocker arms, as required. | ||||||||
Sticking valves. Carbon buildup on the valve stem can cause the valve not to close correctly. | Repair or replace as required. | ||||||||
Timing chain or chains worn or mis-aligned above acceptable tolerances. | Replace the timing chain or chains and sprockets as required. | ||||||||
Worn camshaft lobes. | Replace the camshaft or camshafts and high Stationary Hydraulic Lash Adjusters (SHLAs), valve lifters. | ||||||||
Oil pressure above acceptable tolerances. A lubrication system with oil pressure above acceptable tolerances may lead to valve lifter pump-up above acceptable tolerances and loss of compression. |
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Faulty cylinder head gaskets and/or cracking or other damage to the cylinder heads and cylinder block cooling system passages. Refer to Diagnostic Starting Point - Engine Cooling. Coolant consumption may or may not cause the engine to overheat. |
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Worn piston rings. Oil consumption may or may not cause the engine to misfire. |
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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 crankshaft as required. |
