GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 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 - Engine Controls .
    • 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 .

Ignition System
    • Inspect the spark plugs for the correct heat range and size. Refer to Ignition System Specifications .
    • 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
    • An incorrect coolant mix.
    • 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.

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.
    • 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.