Symptom Definition

A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with amount of acceleration.

Possible Cause & Correction Check the following:

• Check for obvious overheating problems.
• Ensure initial timing is correct.
• Check TPS adjustment and operation.
• Check fuel system for low pressure or volume. Also check for induction air leaks.
• Ensure ESC system is operating properly.
• Ensure EGR valve is not open all the time.
• Ensure that TCC system is operating properly.
• Ensure correct PROM is installed in ECM.
• Remove carbon from engine with top engine cleaner.
• If excessive carbon exists in combustion chamber, check for excessive oil burning due to leaking valve guide seals.
• Check for incorrect basic engine parts such as camshaft, cylinder heads and pistons.
• Check that PROM in vehicle is correct for that vehicle. Check with dealer for latest application information.