Detonation/Spark Knock/Pings

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.
- Low coolant.
- Loose water pump belt.
- Restricted air flow to radiator, or restricted water flow through radiator.
- Faulty or incorrect thermostat.
- Coolant sensor, which has shifted in value.
- Correct coolant solution - should be a 50/50 mix of GM #1052753 anti-freeze coolant (or equiv.) and water.
- CHECK:
- Ignition timing. See "Vehicle Emission Control Information" label.
- For poor fuel quality / proper octane rating.
- For correct PROM. (See Service Bulletins).
- THERMAC for staying closed.
- Fuel system for low pressure. See CHART A-6.
- Spark plugs for correct heat range.
- Check EGR system for not opening.
- For proper transmission shift points.
- Check TCC operation.
- For incorrect basic engine parts such as cam, heads, pistons, etc.
- Excessive oil entering combustion chamber.
- Remove carbon with top engine cleaner. Follow instructions on can.
- On vehicles with 7.4L or 5.7L (over 8500 GVW) engine and a dual catalytic converter system, check for an exhaust restriction in the rear converter area.