Detonation/Spark Knock
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
|
| • | If the scan tool readings are normal refer to supporting text
of the Engine Controls Diagnostic Check and there are no
engine mechanical faults, fill the fuel tank with a known high
quality fuel that meets the vehicles minimum octane requirements. Refer
to
Fuel System Specifications
. Road test the vehicle and re-evaluate the vehicles
performance. |
|
Fuel
System
|
| • | Check the items that can cause an engine to run lean long term
fuel trim near 24 percent. For a lean condition, refer to
DTC P0171 or P0174
. |
|
Ignition
System
| Check the spark plugs for being the proper heat range. Refer to
Spark Plug Inspection
.
|
Engine Cooling
System
| Check
for obvious overheating problems:
| • | Low engine coolant--Refer to
Loss of Coolant
in Engine Cooling for the type and amount of
engine coolant to be used. |
| • | Restricted air flow to the radiator or restricted coolant flow
through the radiator. |
|
Engine
Mechanical
| Check for the following engine mechanical problems:
| • | Combustion chambers for excessive carbon buildup--Clean the
combustion chamber by using top engine cleaner. Follow the instructions
on the can. |
| • | Inspect the following components for incorrect basic engine parts: |
| • | Refer to the appropriate procedures in Engine Mechanical-8.1L. |
|
Additional
Checks
|
| • | Check the park/neutral position (PNP) switch operation. |
|
