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 - Engine Controls
.
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 faulty thermostat. Refer to Engine
Overheating
in Engine Cooling. |
| • | 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 Versus 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 FT will be more 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 for the proper operation of the EGR Valve. |
| • | Check the torque converter clutch (TCC) operation. Refer to Torque Converter Diagnosis Procedure (4L60E)
or
Torque Converter Diagnosis
(4L80E) in Automatic Transmission. |
| • | Check the Service Bulletins for calibration updates. |
|
