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Home >> Chevrolet >> 2011 >> Impala LS, 3.9 M >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 4 (Engine Mechanical - 3.5L - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Base Engine Misfire with Abnormal Valve Train Noise

Base Engine Misfire with Abnormal Valve Train Noise

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Cause Correction
Engine oil level overfull, causing aeration Drain excess oil and adjust oil level to proper specification.
Worn or loose rocker arms-The rocker arm bearing end caps and/or needle bearings should intact within the rocker arm assembly. Replace the valve rocker arms as required.
Worn or bent pushrods Replace the pushrods.
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.
Sticking lifters Replace as required.
Malfunctioning camshaft position actuator-Improper viscosity oil, contaminated oil, or a plugged or missing camshaft position actuator filter can cause the camshaft position actuator locking pin to malfunction.
  • Verify correct oil viscosity by changing the engine oil and oil filter and re-evaluating the concern.
  • Inspect for a missing or plugged camshaft position actuator filter.
  • If filter is missing, replace the filter, replace the camshaft position actuator, and change the engine oil and oil filter.
  • If filter is plugged, replace the filter, and change the engine oil and oil filter.
  • If no problem is found with the camshaft position actuator filter, replace the camshaft position actuator and change the engine oil and oil filter.