Detonation/Spark Knock

Definition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

POSSIBLE CAUSE ACTION

Lean operating condition ^ Check computer controls, refer to Computers And Control Systems / Testing and Inspection

Poor or contaminated fuel ^ Check for excessive alcohol content, Testing and Inspection
^ Recommend higher grade fuel

Incorrect fuel pressure ^ Refer to Fuel Delivery Diagnosis, [1][2]Fuel Delivery Diagnosis

Vacuum leak ^ Inspect vacuum hoses for proper routing and damaged lines