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.

PRELIMINARY INSPECTION
^ Perform the careful "Visual And Physical Checks" in Preliminary Checks. Testing and Inspection
^ Fill fuel tank with a premium gasoline that has a minimum octane rating of 92 and reevaluate vehicle performance.
^ CHECK: Torque Converter Clutch (TCC) operation for TCC applying too soon.

COOLING SYSTEM
^ Check for obvious overheating problems:
- Low engine coolant.
- Restricted air flow to radiator, or restricted coolant flow through radiator.
- Inoperative coolant fan circuit.
- Correct coolant solution.

FUEL SYSTEM

NOTICE: To determine if the condition is caused by a rich or lean system, the vehicle should be driven at the speed of the complaint. Monitoring Oxygen Sensor (O2S) voltage will help identify problem.

Lean - Refer to "Diagnostic Aids" found in Diagnostic Trouble Code 25 Lean Air/Fuel Ratio. DTC 25

Rich - Refer to "Diagnostic Aids" found in Diagnostic Trouble Code 26 Rich Air/Fuel Ratio. DTC 26

^ CHECK: For poor fuel quality. proper octane rating.
^ CHECK: Fuel pressure. Refer to Fuel System Pressure Test.

IGNITION SYSTEM
^ CHECK: Spark plugs for proper heat range. Refer to Spark Plug Application. [1][2]Application and ID
^ CHECK: Ignition timing. Refer to Ignition Timing Adjustment. Ignition Timing

ENGINE MECHANICAL
^ CHECK: For excessive oil in the combustion chamber.
- Valve oil seals for leaking.
^ CHECK: Combustion chambers for excessive carbon buildup. Remove carbon with top engine cleaner and follow instructions on can.
^ CHECK: Combustion chamber pressure by performing a compression test.

ADDITIONAL CHECKS
^ CHECK: For correct ECM calibration. Refer to PROM. PROM - Programmable Read Only Memory
^ CHECK: Torque Converter Clutch (TCC) applying too soon.