Detonation/Spark Knock/Pings

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

^ Check for obvious overheating problems.
^ Radiator cap won't hold pressure.
^ Low coolant.
^ Restricted air flow to radiator, or restricted water flow thru radiator.
^ Inoperative electric cooling fan circuit.
^ Faulty or incorrect thermostat.
^ Correct coolant solution.
^ Check for incorrect PROM. (Refer to parameter ED99)
^ Check ignition timing. See Emission Control Information label.
^ Check for inoperative EGR system.
^ Check for restrictions in the MAP sensor vacuum fitting at the upper intake manifold MAP port. Check for vacuum trapped in the MAP sensor. Tee a vacuum gage into the vacuum hose at the fuel pressure regulator. The gage and parameter ED02 should read approximately the same and should respond quickly to changes in engine load.
^ Check fuel system pressure. Should be 40-50 psi (276-345 kPa) at key "ON", engine "OFF" and increase under engine load. If fuel pressure is not in this range, see Chart A-4B. A-4B Dynamic Fuel Pressure Check
^ Perform an injector balance test:
^ Select ECM override ES04 "Injector".
^ While in the injector override select ECM Data ED11 "RPM".
^ Run engine at 1500 RPM with steady throttle.
^ Select each injector (1-8) and disable fuel (Push "Cooler" button) while observing ECM parameter ED11.
^ Check any injector that does not decrease engine RPM by at least 100.
^ Remove carbon with top engine cleaner. Follow instructions on can.
^ Check for leaking valve oil seals.
^ Check for improper operation of transmission and Viscous Converter Clutch (VCC). See Transmission and Drivetrain. Transmission and Drivetrain
^ Check for incorrect basic engine parts such as cam, heads, pistons, etc.
^ Check for poor fuel quality, proper octane rating.
^ Check spark plugs for proper heat range and type. improper heat range or type may overheat the plug and cause pre-ignition.
^ Check for loose intake manifold bolts, see Engine for proper torque procedure. If condition still exists, suggest that owner try different gasoline. Engine