Detonation - Pings, Spark Knock
Symptom: A mild to severe ping, usually worse under load or acceleration. Sounds like something is rattling or knocking in the engine.
POSSIBLE CAUSE ACTION
Spark timing advanced or not retarding ^ Check Spark Controls.
Lean Air-Fuel mixture ^ Check fuel pressure.
^ Check Air-Fuel ratio.
^ Check O2 sensor output.
^ Perform injector balance test (SFI only only).
Poor or contaminated fuel ^ Recommend higher grade fuel