Checks
| Action
|
DEFINITION: A mild to severe ping, usually worse under acceleration.
The engine makes sharp metallic knocks that change with throttle opening.
|
Preliminary Checks
|
| • | Refer to Important Preliminary Checks Before Starting. |
| • | Refer to Visual/Physical Checks. |
| • | Search for bulletins. |
|
Fuel
System
|
| • | Inspect items that can cause an engine to run lean (long term
fuel trim significantly in the positive range). Refer to Diagnostic Aids for
DTC P0171
. |
|
Ignition
System
| Inspect
the spark plugs for proper heat range and reach.
|
Engine Cooling System
| Inspect for obvious
overheating problems:
| • | Restricted air flow to radiator, or restricted water flow through
radiator |
| • | Inoperative electric cooling fan circuits |
| • | Correct coolant solution should be a 50/50 mix of GM 1052753
or equivalent antifreeze coolant and water. |
|
Engine
Mechanical
|
| • | Combustion chambers for excessive carbon buildup--Clean using
Top engine cleaner. Follow instructions on can. |
| • | For incorrect basic engine parts--Inspect the following: |
|
Additional
Checks
|
| • | Test for proper EGR system operation. Refer to
DTC P0401
. |
| • | Inspect the Transaxle Range Switch input with the vehicle in drive
and the gear selector in drive or overdrive. |
| • | Test TCC operation. TCC applying too soon can cause the engine
to spark knock. Refer to
Torque Converter Diagnosis
in Automatic Transaxle - 4T65-E. |
| • | If scan tool readings are normal and there are no engine mechanical
faults, fill the fuel tank with a known quality gasoline that has a minimum
octane reading of 87 and re-evaluate vehicle performance. |
|
