GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Sunfire 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 Detonation/Spark Knock

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
    • Refer to Symptoms .
    • Search for service bulletins.

Fuel System
    • Check for low fuel pressure. Refer to Fuel System Diagnosis .
    •  Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check items that can cause an engine to run lean (long term fuel trim significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 Fuel Trim System Lean .

Ignition System
    • Check the spark plugs for proper heat range and reach. Refer to Spark Plug Visual Diagnosis in Engine Electrical.
    • Check the knock sensor (KS) system for no retard timing.

Engine Cooling System

Check for obvious overheating problems:

    • Low engine coolant.
    • Restricted air flow to radiator, or restricted water flow through radiator.
    • Inoperative electric cooling fan circuit(s).
    • Correct thermostat operation.
    • Correct coolant solution should be a 50/50 mix of Dexcool ® or equivalent antifreeze coolant and water. Refer to Engine Overheating in Engine Cooling.

Engine Mechanical
    • Excessive oil in combustion chamber-Leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
    • High cylinder compression. Refer to the Engine Compression Test in Engine Mechanical .
    • Combustion chambers for excessive carbon buildup. Clean using Top engine cleaner. Follow instructions on can.
    • For incorrect basic engine parts. Inspect the following:
       - Camshafts
       - Cylinder head
       - Pistons, etc.

Additional Checks
    • Check for proper operation of the MAP sensor, making sure the MAP sensor is not out of range. Refer to Manifold Absolute Pressure Sensor Output Diagnosis .
    • Check the Park/Neutral Position Switch input with the vehicle in drive and the gear selector in drive or overdrive.
    • Check TCC operation. TCC applying too soon can cause the engine to spark knock. Refer to Road Test for 4T40 or Road Test for 3T40 in Automatic Transmission.
    • If scan tool readings are normal and there are no engine mechanical malfunctions, fill the fuel tank with a known quality gasoline that has a minimum octane reading of 87 and re-evaluate vehicle performance.