Detonation/Spark Knock/Pings

DETONATION/SPARK KNOCK

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

PRELIMINARY CHECKS
- Perform the careful/physical visual checks.
- Make sure the customer has an actual problem.
- Remove air cleaner (ACL) and check for dirt, or for being plugged. Replace as necessary.
- Check PCV valve system for proper operation by placing finger over inlet hole in PCV valve end several times with the engine idling. PCV valve should snap back. If not, check PCV valve hose for blockage or deterioration and replace if necessary. If PCV valve still fails this test, replace it with the correct part number PCV valve.
- Check for restricted air flow to radiator, or restricted water flow thru radiator.
- Check for faulty or incorrect thermostat.
- Check for correct coolant solution.

SENSOR
- Check for ECT sensor which has shifted in value. Compare ECT sensor resistance to the "Diagnostic Aids" chart on DTC 14 or DTC 15 chart. DTC 15

FUEL SYSTEM

NOTE: To determine if the condition is caused by a rich or lean system, the vehicle should be driven at the speed of the complaint. Monitoring HO2S voltage using Tech 1 scan tool will help identify the problem.
Lean - HO2S voltage below 450 mV
Rich - HO2S voltage above 450 mV

- Check fuel pressure, refer to Chart A-7B Chart A-7B Fuel System Pressure Check and On-Board Diagnostic System Check. Testing and Inspection
- Check for poor fuel quality, proper octane rating.

NOTE: If HO2S voltage readings are normal and there are no engine mechanical faults, fill fuel tank with a premium gasoline that has a minimum octane rating of 92 and reevaluate vehicle performance.

IGNITION SYSTEM
- Check ignition timing. See "Vehicle Emission Control Information" label.
- Check spark plugs for proper heat range.
- Check ignition wires for shorts or faulty insulation.
- Check for misfiring, crossfiring or cutting out under load.

ENGINE MECHANICAL
- Check for carbon buildup. Remove carbon with top engine cleaner. Follow instructions on can.
- Check for incorrect basic engine parts such as cam, heads, pistons, etc.
- Check for excessive oil entering combustion chamber.

ADDITIONAL CHECKS
- Check EGR system operation, refer to Chart C-7. Chart C-7 EGR System Check
- Check for proper transmission shift points.
- Check torque converter clutch (TCC) operation, refer to Chart C-8. Chart C-8 TCC Lock-Up Relay System Check
- Check for correct ECM, see Service Bulletins.