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. |
| • | Check for a low engine coolant level. |
| • | Check for a loose water pump belt. |
| • | Check for restricted air flow or restricted coolant flow through
the radiator. |
| • | Check for a faulty or incorrect thermostat. |
| • | Check for the correct coolant solution. The solution should be
a 50/50 mix of anti-freeze and water. |
|
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 Fuel Trim System Lean
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.
|
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 the proper operation of the air induction system. |
| • | Check the Service Bulletins for any updates or information. |
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