Detonation/Spark-Knock/Pings
SYMPTOM DESCRIPTION:
A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
POSSIBLE CAUSE ACTION
Lean air/fuel mixture ^ Check computer controls. SEE Computers and Control Systems.
Poor or contaminated fuel ^ Check for excessive alcohol content.
^ Recommend higher grade fuel.
Incorrect fuel pressure ^ Check fuel pressure.
Vacuum leak ^ Inspect vacuum hoses for proper routing and damaged lines.
^ Check intake manifold, throttle body, etc.