Detonation/Spark Knock

Symptom: The engine makes a sharp metallic knock as engine rpm varies. A mild or severe ping, usually worse under acceleration.


POSSIBLE CAUSE ACTION

COOLING SYSTEM MALFUNCTION - Check overheating problems: low coolant level, leaks, water pump operation, loose belts, faulty or incorrect thermostat, restricted air flow through radiator, restricted coolant flow, incorrect coolant solution (should be 50/50), and proper radiator cooling fan operation.

FUEL SYSTEM MALFUNCTION - Check fuel pressure.

- Check for lean Air-Fuel mixture, (O2S Sensor output).

- Perform injector balance test.

- Check fuel quality.

IGNITION SYSTEM MALFUNCTION - Check SPARK PLUGS for proper heat range.

- Check IGNITION TIMING for excessive spark advance. SEE Powertrain Management/Ignition System/Specifications.

EMISSIONS COMPONENT MALFUNCTION - Check EGR valve for binding or sticking in the closed position.

- Check EGR Transducer for proper operation.

- Check Thermostatic Air Cleaner for proper operation.

ENGINE MECHANICAL - Check for carbon buildup on pistons. Remove carbon with top engine cleaner. Follow instructions on can.

- Check for excessive oil entering combustion chambers.

TRANSMISSION MALFUNCTION - Check for proper transmission shift points.

- Check for proper Torque Converter Clutch (TCC) operation, if applicable.