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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Shelby Series 1 🢒 Engine 🢒 Engine Controls - 4.0L 🢒 Detonation/Spark Knock

Detonation/Spark Knock

Checks

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 Checks
    • Refer to Important Preliminary Checks Before Starting in Symptoms .
    • Search for bulletins.
    • Inspect the powertrain control module (PCM) grounds for being clean, tight, and in their proper locations. Refer to Engine Controls Schematics .
    • If the scan tool readings are normal, refer to supporting text of the Powertrain On Board Diagnostic (OBD) System Check . If there are no engine mechanical faults, fill the fuel tanks with a known high quality fuel that meets the vehicle minimum octane requirements. Refer to Fuel System Specifications . Road test the vehicle and reevaluate the vehicle performance.

Fuel System
    • Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Test for a restricted fuel filter. Refer to Fuel System Diagnosis .
    • Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Test the items that can cause an engine to run lean. For a lean condition, refer to DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 and DTC P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1 .

Ignition System

Inspect the spark plugs for being the proper heat range.

Engine Cooling System

Test for obvious overheating problems:

    • Low engine coolant -- Verify the type and amount of engine coolant to be used.
    • Restricted air flow to the radiator or restricted coolant flow through the radiator
    • Inoperative electric cooling fan circuits

Engine Mechanical

Inspect for the following engine mechanical problems:

    • Excessive oil in combustion chamber or leaking valve seals
    • High 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 the following incorrect basic engine parts:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.