Detonation/Spark Knock
Checks
| Action
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DEFINITION: A mild to severe ping which usually occurs worse while under acceleration. The engine makes sharp metallic knocks that change with throttle opening.
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Preliminary Checks
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• | Verify that the engine control module (ECM) grounds are clean, tight, and in the correct locations. |
• | If the scan tool readings are normal and there are no engine mechanical conditions, 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. |
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Fuel System
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• | Test or inspect items that can cause an engine to run lean. For a lean condition, refer to
DTC P0171
. |
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Sensor/System
| Use a scan tool to monitor the knock sensor (KS) system. Refer to
Knock Sensor (KS) System Description
.
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Ignition System
| Verify that the spark plugs are of the correct heat range. Refer to
Ignition System Specifications
.
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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 |
• | Incorrect fan operation |
| Refer to the following procedures in Engine Cooling: |
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Engine Mechanical
| Inspect for the following engine mechanical conditions:
• | Excessive oil in the combustion chambers and for leaking valve seals. |
• | Excessive carbon buildup in the combustion chambers. Clean the chambers with top engine cleaner. Follow the instructions on the can. |
• | Inspect the following for incorrect basic engine parts: |
- | The pistons, connecting rods, and bearings |
- | Refer to the following procedures in Engine Mechanical - 1.4L DOHC: |
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Additional Checks
| Test the transmission torque converter clutch (TCC). Applying the TCC too soon can cause the engine to spark knock. Refer to
Symptoms - Automatic Transmission
in Automatic Transmission - Aisin (81-40LE).
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