GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1996 🢒 Bravada 🢒 Engine 🢒 Engine Controls - 4.3L (VIN W) 🢒 Detonation/Spark Knock

Check

Action

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

Preliminary Checks
    • Refer to Important Preliminary Checks .
    • Make sure the customer has an actual problem.
    • Check the Transmission Range (TR) pressure switch assembly operation. Refer to Electronic Component Description .

Cooling System Checks
    • Check for an obvious overheating problem. Refer to Engine Cooling.
    • Check for a low engine coolant level.
    • Check for the proper tension on the drive belts.
    • Check for restricted air flow through the radiator, or restricted coolant flow.
    • Check for a faulty thermostat, refer to Engine Cooling.
    • Check for a correct coolant solution. The coolant should be a 50/50 mix of antifreeze and water.

Sensor Check

Check for an Engine Coolant Temperature (ECT) sensor that has a shift in value. Refer to the following items:

Fuel System Checks
    • Check if a Lean system causes this condition. Drive the vehicle at the speed of the complaint. Monitoring the Fuel Trim will help identify the problem.
    • If the system is Lean, the Long Term Fuel Trim will be greater than 150. Refer to the following items:
       -  DTC P0132 HO2S Circuit High Voltage Sensor 1 for the 4.3L Diagnostic Aids or DTC P0132 O2S Circuit High Voltage Sensor 1 for the 2.2L Diagnostic Aids
       -  DTC P0138 HO2S Circuit High Voltage Sensor 2 for the 4.3L Diagnostic Aids or DTC P0138 HO2S Circuit High Voltage Sensor 2 for the 2.2L Diagnostic Aids
    • Check the fuel pressure. Refer to Fuel System Pressure Test or the 4.3L or Fuel System Pressure Test for the 2.2L.
    • Check for a poor fuel quality and a proper octane rating.
    • If the scan tool readings are normal and there are no engine mechanical faults, fill the fuel tank with a premium gasoline that has a minimum octane rating of 92 and re-evaluate the vehicle's performance.

Ignition System Checks
    • Check the spark plugs for their proper heat range and gap.
    • Check the Knock Sensor (KS) system operation. Refer to Knock Sensor (KS) System Diagnosis (Overview) for the 4.3L or Knock Sensor (KS) System Diagnosis for the 2.2L.
    • Check the ignition timing. Refer to Enhanced Ignition System Diagnosis (Overview) for the 4.3L or Electronic Ignition (EI) System Diagnosis for the 2.2L.

Engine Mechanical Checks
    • Check for carbon build up. Remove the carbon with a top engine cleaner. Follow the instructions on the can.
    • Check the combustion chamber pressure by performing a compression test. Refer to Engine Mechanical.

Additional Checks
    • Check for the proper operation of the EGR Valve. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis for the 4.3L and 2.2L.
    • Check for the proper operation of the Air Intake system. Refer to Air Induction System (Overview) .
    • Check for the proper operation of the transmission shift points. Refer to the Transmission Controls section.
    • Check the Torque Converter Clutch (TCC) operation. Refer to Automatic Transmission.
    • Check the Service Bulletins for PROM updates.