Detonation/Spark Knock

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

Ignition Systems
- Spark plugs for correct heat range.
- Ignition timing.
- Distributor cap (if applicable) for arcing or carbon tracking inside cap.

Fuel Systems
- Fuel system for low pressure.
- For poor fuel quality--proper octane rating.

Emission Systems
- Check EGR valve for not opening.

Engine Mechanical
- For incorrect basic engine parts such as cam, heads, pistons, etc.
- Excessive oil entering combustion chamber.
- Carbon build-up on pistons or combustion chamber.
- Engine overheating.
- Turbo operation if applicable.