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

Detonation/Spark Knock

Tests/Inspections

Action

DEFINITION: A mild to severe Ping, usually worse under acceleration. The engine makes sharp metallic knocks that change with throttle opening.

Preliminary
    • Refer to Symptoms .
    • Search for service bulletins.

Fuel System
    • Test the fuel pressure. Refer to Fuel System Diagnosis .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect the 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
    • Inspect the spark plugs for the correct heat range and size. Refer to Spark Plug Visual Diagnosis in Engine Electrical.
    • Use a scan tool in order to verify that the ignition timing is not retarding.

Cooling System

Inspect for obvious overheating problems:

    • A low coolant level
    • A restricted air flow to the radiator, or a restricted water flow through radiator
    • Any inoperative cooling fans
    • An incorrect thermostat operation. Refer to Thermostat Diagnosis in Engine Cooling.
    • An incorrect coolant mix. Refer to Coolant Concentration Testing in Engine Cooling.

Engine Mechanical
    • Any excessive oil in the combustion chamber and leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
    • A high cylinder compression. Refer to Engine Compression Test in Engine Mechanical.
    • For any incorrect basic engine parts. Inspect the following:
       - The camshafts
       - The cylinder head
       - The pistons, etc.

Additional
    • Test for the correct operation of the manifold absolute pressure (MAP) sensor. Verify that the MAP sensor is not out of range. Refer to Manifold Absolute Pressure Sensor Output Diagnosis .
    • Inspect the Park/Neutral position switch input with the vehicle in drive and the gear selector in drive or overdrive.
    • Test for correct operation of the TCC. A TCC applying too soon can cause the engine to spark knock. Refer to Road Test in Automatic Transaxle.
    • If scan tool readings are normal and there are no engine mechanical malfunctions, fill the fuel tank with a known good gasoline that has a minimum octane reading of 87 and re-evaluate the vehicle's performance.