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, Pinpoint Tests

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