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Basic engine misfiring in connection with abnormal noise from valve guide (A20NFT/LHU)

Basic engine misfiring in connection with abnormal noise from valve guide (A20NFT/LHU)


Cause Procedure
Worn or loose rocker arms The rocker arm's bearing caps and/or needle bearings must be intact in the rocker arm. Replace the rocker arms if necessary.
Valves that have jammed Carbon deposits on the valve stem may mean that the valve does not close properly. Repair or replace any defective or damaged components.
Heavily worn or misaligned timing chain Replace timing chain and sprocket if necessary.
Worn camshaft cams Replace the camshafts and valve clearance balancers.
Tappets that have jammed Replace if necessary.
Malfunctions in camshaft position regulators - incorrect oil viscosity or contamination.
1. Check that the oil pressure is correct. If the pressure is low, inspect the bottom of the oil filter with regard to the return feed. See Diagnosis and testing of oil pressure (A20NFT/LHU) .

2. Isolate the noise to a specific camshaft position regulator. Disconnect the electrical connector from the camshaft position regulator's solenoid valves and start the car. If the noise disappears, repeat the procedure to limit it to a single actuator. Information is available in "Replacing the camshaft position intake actuator" or "Replacing the camshaft position exhaust actuator".