Detonation Pings, Spark Knock

A mild to severe ping, usually worse under load or acceleration. Sounds like something is rattling or knocking in the engine.

POSSIBLE CAUSE ACTION

EGR inoperative Check EGR system in TESTING PROCEDURES

Ignition timing advanced Check Ignition Timing

Spark timing not retarding Check Spark Controls in COMPUTERIZED ENGINE CONTROLS

Poor or contaminated fuel Recommend higher grade fuel