Detonation/Spark Knock/Pings

DEFINITION: A mild to severe "knock" or "ping" (Makes sharp metallic knocks that change with engine load and speed), Usually worse under acceleration.

^ Check EGR System for proper operation.
^ Check ignition timing. See Vehicle Emission Control Information label.
^ Check for obvious overheating problems. Use "Scan" tool if available. 85-1OO°C (185-215°F) is normal.
- Low coolant.
- Loose water pump belt.
- Restricted air flow to radiator, or restricted water flow through radiator.
- Inoperative fan clutch.
^ Check for air leaks at carburetor mounting and intake manifold.
^ Check for incorrect PROM.
^ Check for proper operation of TCA.
^ Check for poor fuel quality, try better grade of gasoline.
^ Check TPS WOT enrichment operation.
^ Remove carbon with top engine cleaner. Follow instructions on can.
^ If excessive carbon in cylinders, check for leaking valve seals.
^ Check for incorrectly modified engine (high performance parts such as high lift cams, high compression pistons or cylinder heads, can sometimes cause engine knocks).
^ Listen for lower end engine noise, make sure knock is not caused by worn connecting rod or main engine bearings.