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. Long Term Fuel Trim values will be greater than
20% 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's 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 the correct
gap. |
|
Engine Mechanical Checks
|
| • | Check for carbon buildup. Remove the carbon with a top engine
cleaner. Follow the instructions supplied by the product manufacturer. |
| • | Check for the use of the wrong camshaft, cylinder head, piston(s),
or other incorrect engine part. Refer to Engine Mechanical. |
| • | Check for excessive oil entering the combustion chamber. |
|
Additional Checks
|
| • | Check for the proper operation of the air induction system. |
| • | Check the Service Bulletins for any updates. |
|
