| Abnormalities (severe cracking, bumps or missing areas) in the accessory drive belt. Also worn, damaged or misaligned accessory drive components or excessive pulley runout. |
Abnormalities in the accessory drive belt 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.
- Inspect the accessory drive components.
- Repair or replace all damaged components.
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| Loose and/or damaged crankshaft pulley |
A misfire code may be present without an actual misfire condition.
- Inspect crankshaft pulley and pulley bolt.
- Repair or replace all damaged components.
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| Loose torque converter bolts |
A misfire code may be present without an actual misfire condition.
- Inspect torque converter bolts and flywheel.
- Repair or replace all damaged components.
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| Loose and/or damaged flywheel |
A misfire code may be present without an actual misfire condition.
- Inspect flywheel and flywheel attaching bolts.
- Repair or replace all damaged components.
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| Restricted exhaust system |
A severe restriction in the exhaust flow can cause significant loss of engine performance and may set a misfire code. Possible causes of restrictions include collapsed or dented pipes, plugged mufflers and/or catalytic converters. Repair or replace all damaged components. |
| Air in fuel system |
- Inspect fuel filter, fuel system for leaks and/or restrictions.
- Repair or replace all damaged components.
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| Bent and/or worn valve bridge and finger-follower |
- Inspect valve bridge and valve finger-follower.
- Repair or replace all damaged components.
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| Sticking valve |
Carbon on the valve stem or valve seat may cause the valve to stick.
- Inspect valves and valve guides.
- Repair or replace all damaged components.
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| Damaged or misaligned timing gears |
- Inspect timing gears.
- Replace all damaged components.
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| Worn or faulty camshaft lobes |
- Inspect camshaft lobes.
- Repair or replace all damaged components.
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| Excessive piston-to-cylinder bore clearance |
- Perform compression tests.
- Inspect the piston, piston rings and cylinder bore.
- Repair or replace all damaged components.
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| 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.) |
- Perform compression tests.
- Inspect the piston, piston rings and cylinder bore.
- Repair or replace all damaged components.
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