Detonation/Spark Knock/Pings

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

PRELIMINARY CHECKS
Perform the careful visual/physical check as described in Preliminary Checks.
If Tech 1 readings are normal and there are no engine mechanical faults, fill fuel tank with a premium gasoline that has a minimum octane reading of 91 and re-evaluate vehicle performance.

COOLING SYSTEM
Check for obvious overheating problems:
- Low engine coolant.
- Loose water pump belt.
- Restricted air flow to radiator or restricted water flow through radiator.
- Inoperative electric cooling fan circuit, use Chart C-12.
- Correct coolant solution should be a 50/50 mix of GM #1052753 anti-freeze coolant (or equivalent) and water.

FUEL SYSTEM

NOTICE: To determine if the condition is caused by a rich or lean HO2S signal, the vehicle should be driven at the speed of the complaint. Monitoring long term fuel trim will help identify the problem.

Lean - Long term fuel trim near 160. Refer to "Diagnostic Aids" in DTC 42 or 44.

Rich - Long term fuel trim near 115. Refer to "Diagnostic Aids" in DTC 43 or 45.
Refer to "Diagnostic Aids" in DTC 46. Testing and Inspection

CHECK: Fuel pressure, use Chart A-7. Testing and Inspection

IGNITION SYSTEM
Check:
Spark plugs for constant heat range.
Knock Sensor (KS) system for no retard, use Chart C-5. Testing and Inspection

ENGINE MECHANICAL
Check:
For excessive oil in the combustion chamber.
Combustion chambers for excessive carbon buildup. Remove carbon with top engine cleaner and follow instructions on can.
Perform a cylinder compression test.
For incorrect basic engine parts such as cams, heads, pistons, ect.

ADDITIONAL CHECKS
Check:
Proper Torque Converter Control (TCC) operation.
For correct Programmable Read Only Module (PROM). (Refer to Service Bulletins.)
Check Exhaust Gas Recirculation (EGR) operation. Use Chart C-7. Testing and Inspection