Detonation -- Pings & Spark Knocks

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" in Emissions



Ignition timing advanced Check Ignition Timing in "Adjustment
Procedures" in Emissions



Air damper door binding, Check inlet air temperature system (TAC)
air cleaner temperature in "Testing Procedures" in Emissions
control malfunction



Spark timing not retarding Check Spark Controls in
"Fuel Injection and Computerized
Engine Controls"



Poor or contaminated fuel Recommend higher grade fuel