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 Computers and Control Systems

Poor or contaminated fuel Check for excessive alcohol content

Recommend higher grade fuel

Incorrect fuel pressure Proceed to FUEL PRESSURE TEST Testing and Inspection

Vacuum leak Inspect vacuum hoses for proper routing and damaged lines

Check intake manifold and throttle chamber base