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 for obvious over heating problems, low engine coolant level and leaks, water pump operation, loose belts, Faulty or incorrect thermostat, restricted air flow to radiator or restricted coolant flow, incorrect coolant solution (should be 50/50), proper fan operation (electric or belt driven).

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 PLUG heat range.

- Check for advanced spark timing.
SEE Powertrain Management/Ignition System/Specifications.

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.