Detonation - Pings, Spark Knock

DEFINITION:

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

CHECK for obvious overheating problems, 85°C-100°C (185°F-215°F) is normal.
- Low coolant.
- Loose water pump belt.
- Restricted air flow to radiator, or restricted water flow thru radiator.
- Faulty or incorrect thermostat.
- Correct coolant solution - should be a 50/50 mix of anti-freeze/coolant and water.

CHECK:
- For air leaks at throttle body base or intake manifold gaskets.
- THERMAC operation (damper valve should be open to fresh air intake duct when engine is warm or hot)
- Distributor cap for arcing or carbon tracking inside cap.
- For poor fuel quality, proper octane rating.
- For correct Mem-Cal or PROM.
- Spark plugs for correct heat range.
- Ignition timing. See Vehicle Emission Control Information label.
- Fuel system for low pressure.
- Check EGR valve for not opening.
- For incorrect basic engine parts such as cam, heads, pistons, etc.
- Excessive oil entering combustion chamber.
- Carbon build-up on pistons or combustion chamber. Remove carbon with top engine cleaner. Follow instructions on can.

Remove air cleaner and visually check injectors. If there is spray from only one injector, then, there is a malfunction in the injector assembly, or in the signal to the injector assembly. The malfunction can be isolated, by switching the injector connectors. If the problem remains with the original injector, after switching the connectors, then, the injector is defective. Replace the injector. If the problem moves with the injector connector, then, the problem is an improper signal in the injector circuits.