Detonation/Spark Knock

Definition: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening. Sounds like popcorn popping.
^ Check for obvious overheating problems:
- Low coolant.
- Loose water pump belt.
- Restricted air flow to radiator, or restricted water now thru radiator.
- Inoperative electric cooling fan circuit.
See CHART C-12.
^ CHECK:
- Ignition timing. See Vehicle Emission Control Information label.
- EGR system for not opening - CHART C-7.
- TCC operation - CHART C-8.
- Fuel system pressure. See CHART A-7.
- PROM - Be sure it's the correct one. (See Service Bulletins)
- Valve Oil seals for leaking.
^ Check for incorrect basic engine parts such as cam, heads, pistons, etc.
^ Check for poor fuel quality.
^ Remove carbon with top engine cleaner. Follow instructions on can.