Detonation/Spark Knock/Pings

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

Preliminary Checks

- Refer to Important Preliminary Checks.

- Make sure the customer has an actual problem.

- Check the Transmission Range (TR) pressure switch assembly operation.

Cooling System Checks

- Check for an obvious overheating problem. Refer to the Cooling System.

- Check for a low engine coolant level.

- Check for the proper tension on the drive belts.

- Check for restricted air flow through the radiator; or restricted coolant flow.

- Check for a faulty thermostat.

- Check for a correct coolant solution. The coolant should be a 50/50 mix of antifreeze and water.

Sensor Check

Check for an Engine Coolant Temperature (ECT) sensor that has a shift in value. Refer to the following items:

- DTC P0118 ECT Sensor Circuit High Voltage Diagnostic Aids. P0118

- DTC P0125 ECT Excessive Time to Closed Loop Diagnostic Aids. P0125

Fuel System Checks

- Check if a Lean system causes this condition. Drive the vehicle at the speed of the complaint. Monitoring the Fuel Trim will help identify the problem.

- If the system is Lean, the Long Term Fuel Trim will be greater than 150. Refer to the following items:

- DTC P0132 O2S Circuit High Voltage Sensor 1 Diagnostic Aids. P0132

- DTC P0138 O2S Circuit High Voltage Sensor 2 Diagnostic Aids. P0138

- Check the fuel pressure. Refer to Fuel System Pressure Test. System Diagnosis - Fuel System Pressure Test

- Check for a poor fuel quality and a proper octane rating.

- If the scan tool readings are normal and there are no engine mechanical faults, fill the fuel tank with a premium gasoline that has a minimum octane rating of 92 and re-evaluate the vehicle's performance.

Ignition System Checks

- Check the spark plugs for their proper heat range and gap.

- Check the Knock Sensor (KS) system operation. Refer to Knock Sensor System Diagnosis. System Diagnosis - Knock Sensor (KS)

- Check the ignition timing. Refer to Enhanced Ignition System Diagnosis.

Engine Mechanical Checks

- Check for carbon build up. Remove the carbon with a top engine cleaner. Follow the instructions on the can.

- Check the combustion chamber pressure by performing a compression test. Refer to Engine.

Additional Checks

- Check for the proper operation of the Exhaust Gas Recirculation (EGR) Valve. Refer to EGR System Diagnosis. System Diagnosis - EGR

- Check for the proper operation of the Air Intake system. Refer to Air Induction System.

- Check for the proper operation of the transmission shift points.

- Check the Torque Convener Clutch (TCC) operation. Refer to Torque Converter Clutch Solenoid in Automatic Transmission.

- Check the Service Bulletins for PROM updates.