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
.
Verify the customer concern.
|
Cooling System Checks
|
| • | Check for a low engine coolant level. |
| • | Check for the proper tension on the drive belts. |
| • | Check for restricted air flow through the radiator, or restricted
coolant flow. |
| • | Check for a correct coolant mixture. |
|
Sensor Check
| Check for an Engine Coolant Temperature (ECT) sensor that
has a shift in value. Refer to Temperature vs 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 greater
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's performance. |
|
Ignition System Checks
|
| • | Check the spark plugs for their proper heat range and gap. |
| • | Check the Knock Sensor (KS) system operation. |
| • | 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. |
|
Additional Checks
|
| • | Check the Service Bulletins for calibration updates. |
|
