Checks
| Action
|
DEFINITION: A mild
to severe ping that is usually worse under acceleration. The engine makes
sharp metallic knocks that change with throttle opening.
|
Preliminary Checks
|
| • | Road test the vehicle in order to determine the severity of the
condition. |
|
Cooling System Checks
|
| • | Check for any obvious overheating problems. Refer to
Engine Overheating
in Engine Cooling. |
| • | Check for a low engine coolant level. Refer to
Loss of Coolant
in Engine Cooling. |
| • | Check for a loose water pump belt. |
| • | Check for restricted air flow or restricted coolant flow through
the radiator. |
| • | Check for the correct coolant solution. The solution should be
a 50/50 mix of anti-freeze and water. Refer to
Coolant Concentration Testing
in Engine Cooling. |
|
Sensor Check
| Check for an engine coolant temperature (ECT) sensor that has a shifted value.
Refer to
Temperature Versus Resistance
.
|
Fuel System Checks
|
| • | Determine whether lean fueling is causing the condition. Drive
the vehicle at the speed of the complaint. Monitor the Fuel Trim value while
listening for engine noise. The long term fuel trim values will be approaching
20 percent if a lean fueling condition is present. Refer to
DTC P0171
Diagnostic Aids. |
| • | Check for inferior quality fuel and the correct octane rating.
Refer to
Fuel System Specifications
.
Drain and fill the fuel system with a known high quality fuel that meets
the vehicle minimum octane requirements. Road test the vehicle and re-evaluate
vehicle performance. |
|
Ignition System Checks
| Check the spark plugs for the proper
heat range and gap. Refer to
Ignition System Specifications
.
|
Engine Mechanical Checks
|
| • | Check for carbon buildup. Remove the carbon buildup with Top engine
cleaner. Follow the instructions on the container. |
| • | Check for incorrect basic engine parts such as the cam, the heads,
the pistons, etc. |
| • | Check for an excessive quantity of oil entering the combustion
chamber. Refer to
Oil Consumption Diagnosis
in Engine Mechanical. |
|
Additional Checks
|
| • | Check for the proper shifting and operation of the transmission. |
| • | Check for a dirty air filter or restrictions in the air induction
system. |
| • | Check the Service Bulletins for any updates or information. |
|
