Detonation/Spark Knock
Inspection/Tests
| Action
|
DEFINITION: A mild to severe ping, usually worse under acceleration. The engine
makes sharp metallic knocks that change with throttle opening.
|
Preliminary Inspections
|
| • | If there are no engine mechanical faults, fill the fuel tank with a known
high quality fuel that meets the vehicles minimum octane requirements. Road test the
vehicle and re-evaluate the vehicles performance. |
|
Fuel System
|
| • | Inspect for the following conditions that may cause the engine to run
lean: |
Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section. | - | Water intrusion in the heated oxygen sensor (HO2S) connector |
| - | An exhaust leak between the HO2S and the engine--Refer to
Exhaust Leakage
. |
| - | Vacuum hoses that are split, kinked, or improperly connected |
|
Ignition System
| Verify that the spark plugs are of the proper heat range. Refer to
Spark Plug Inspection
.
|
Engine Cooling System
| Inspect for obvious overheating conditions:
| • | Low engine coolant--Refer to
Loss of Coolant
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
| Inspect for the following engine mechanical conditions:
| • | Excessive oil in combustion chamber--Leaking valve seals. |
| • | Low cylinder compression . |
| • | Combustion chambers for excessive carbon buildup--Clean the combustion
chamber by using top engine cleaner. Follow the instructions on the can. |
| • | Inspect for incorrect basic engine parts. Inspect the following: |
|
Additional Inspections
|
| • | Inspect the transmission torque converter clutch (TCC) operation. The
TCC applying too soon can cause the engine to spark knock. |
|
