| DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with the throttle opening. |
| Preliminary |
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| Cooling System |
- Inspect for a low engine coolant level.
- Inspect for a correct coolant mixture.
- Inspect for the proper tension on the drive belts. Refer to Drive Belt Tensioner Diagnosis
in Engine Mechanical.
- Inspect for restricted air flow through the radiator, or restricted coolant flow.
- Inspect for a faulty thermostat. Refer to Thermostat Diagnosis
in Engine Cooling.
|
| Sensor/System |
Inspect for an Engine Coolant Temperature (ECT) sensor that has a shift in value. Refer to Temperature vs Resistance
. |
| Fuel System |
- Drive the vehicle at the speed of the complaint. Monitoring the fuel trim will help identify the problem.
- If the system is lean, the long term fuel trim will be more than 150.
- Test the fuel pressure. Refer to Fuel System Diagnosis .
- Inspect for a poor fuel quality and a proper octane rating.
- If the fuel trim readings are normal and there are no engine mechanical concerns, then fill the fuel tank with a known good fuel and re-evaluate the vehicle performance.
|
| Ignition System |
- Inspect the spark plugs for their proper heat range and gap.
- Inspect the knock sensor (KS) system operation.
- Inspect the ignition timing.
|
| Engine Mechanical |
- Inspect for carbon build up. Remove the carbon with a top engine cleaner. Follow the instructions on the can.
- Test the combustion chamber pressure by performing a compression test. Refer to Engine Compression Test
in Engine Mechanical.
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| Additional |
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