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 Important Preliminary Checks
. |
| • | Make sure the customer has an actual problem. |
| • | Check the Transmission Range (TR) pressure switch assembly operation.
Refer to Transmission Fluid Pressure Switch Assembly
. |
|
Cooling System Checks
|
| • | Check for an obvious overheating problem. Refer to the Diagnosis of the Cooling System
in Engine Cooling. |
| • | 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 Diagnosis
of the Thermostat
in Engine Cooling. |
| • | Check for a correct coolant solution. The coolant should be a
50/50 mix of antifreeze and water. |
|
Sensor Check
| Check for an Engine Coolant
Temperature (ECT) sensor that has a shift in value. Refer to the following
items:
|
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. Refer to the following items: |
| • | Check for a poor fuel quality and a proper octane rating. |
| • | If the scan tool readings are normal and there are no engine mechanical
faults, fill the fuel tank with a premium gasoline that has a minimum octane
rating of 92 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. Refer to Knock Sensor (KS) System Diagnosis (Overview)
. |
| • | Check the ignition timing. Refer to Enhanced Ignition System Diagnosis (Overview)
. |
|
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. Refer to Engine Mechanical. |
|
Additional Checks
|
| • | Check for the proper operation of the Air Intake system. Refer
to Air Induction System (Overview)
. |
| • | Check for the proper operation of the transmission shift points.
Refer to the Transmission Controls section. |
| • | Check the Torque Converter Clutch (TCC) operation. Refer to Torque Converter Clutch Solenoid
in Automatic Transmission. |
| • | Check the Service Bulletins for PROM updates. |
|
