Check
| Action
|
DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with the throttle opening.
|
Preliminary Checks
| Refer to
Symptoms - Engine Controls
.
Verify the customer concern.
|
Cooling System Checks
|
| • | Check for a low engine coolant level. |
| • | Check for restricted air flow through the radiator, or restricted coolant flow. Refer to
Radiator Cleaning
in Engine Cooling. |
|
Sensor Check
| Check for
an engine coolant temperature (ECT) sensor that has a shift in value. Refer
to
Temperature Versus Resistance
.
|
Fuel
System Checks
|
| • | Check if a lean system causes this condition. 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. |
| • | Check 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 Checks
|
| • | Check the knock sensor (KS) system for excessive spark retard activity. |
| • | Check the ignition timing. |
|
Engine Mechanical Checks
|
| • | Check for carbon build up. Remove the carbon with a top engine cleaner. Follow the instructions on the can. |
| • | Check the combustion chamber pressure by performing a compression test. Refer to
Engine Compression Test
in Engine Mechanical. |
|
Additional Checks
|
| • | Check the Service Bulletins for calibration updates. |
|
