Inspection
| Action
|
DEFINITION: A mild to severe ping which usually occurs worse while under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
|
Preliminary
|
• | Inspect the engine control system grounds for being clean, tight, and in the correct locations. Refer to
Engine Controls Schematics
. Ensure the resistance between the engine control module (ECM) housing and
the battery negative cable is less than 0.5 ohms. |
• | Verify that the ECM and ECM bracket fasteners are at the correct torque. |
• | If the scan tool readings are normal and there are not any engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicle's minimum octane requirements. Road test the vehicle and re-evaluate the vehicle's performance. |
|
Fuel System
|
|
Sensor/System
| Use a scan tool to monitor the knock sensor (KS) system. Refer to
Knock Sensor (KS) System Description
.
|
Ignition System
| Ensure that the spark plugs are the correct heat range. Refer to
Ignition System Specifications
.
|
Engine Cooling System
| Test for obvious overheating conditions. Test or inspect for the following conditions:
• | Low engine coolant level |
• | Incorrect engine coolant |
• | Restricted air flow to the radiator or restricted coolant flow through the radiator |
| Refer to the following procedures: |
|
Engine Mechanical
|
• | Inspect for the following engine mechanical conditions: |
- | Excessive oil in combustion chambers and for leaking valve seals. |
- | High cylinder compression. |
- | Incorrect camshaft timing. |
- | Excessive carbon buildup in the combustion chambers. Clean the chambers using top engine cleaner. Follow the instructions on the can. |
- | For more information, refer to the following procedures: |
• | Inspect the following components for incorrect basic engine parts: |
- | Pistons, connecting rods or bearings. |
- | Refer to the following procedures: |
|
Additional
| Test the transmission torque converter clutch (TCC) for the correct operation. Applying the TCC too soon can cause the engine to spark knock. Refer to
Torque Converter Diagnosis
.
|