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 restricted air flow or restricted coolant flow through
the radiator. |
|
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. |
|
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. |
|