GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Surges/Chuggles

Checks

Action

DEFINITION: Engine power variation during steady throttle or cruise. The vehicle seems to speed up and slow down with no change in the accelerator pedal.

Preliminary
    • Refer to Important Preliminary Checks.
    • Refer to Visual/Physical Checks.
    • Search for bulletins.
    • Ensure that the driver understands the transmission torque converter clutch and the A/C compressor operation, as explained in the owner's manual. Inform the customer how the TCC and the A/C clutch operate.

Sensor/System
    • Test the Heated Oxygen Sensors. The Heated Oxygen Sensors should quickly respond to different throttle positions. If not, inspect the HO2S for silicon or for other contaminants from fuel or from the use of an improper RTV sealant. The sensors may have a white powdery coating. Silicon contamination causes a high but false HO2S signal voltage, indicating a rich exhaust. The PCM will reduce the amount of fuel that is delivered to the engine, causing a severe driveability problem. Refer to Information Sensors/Switches Description .
    • Inspect the MAF Sensor and the related wiring.
    • Test the EGR system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .

Fuel System
    • Test the fuel pressure. Refer to Fuel System Pressure Test (VIN K) and refer to Fuel System Pressure Test (VIN 1) .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Alcohol-in-Fuel Diagnosis .
    • Ensure that each injector harness is connected to the correct injector and cylinder.
    • Inspect for conditions which can cause an engine to run rich, indicating that the long-term fuel trim is significantly in the negative range. Refer to Diagnostic Aids for DTC P0172 Fuel Trim System Rich .
    • Inspect for conditions that can cause an engine to run lean, indicating that the long-term fuel trim is significantly in the positive range. Refer to Diagnostic Aids for DTC P0171 Fuel Trim System Lean .

Ignition System
    • Use the following steps in order to test for proper ignition voltage output:
        1. Clip the spark tester J 26792 to an engine ground.
        2. Connect one end of a spark plug wire to the spark tester, and leave the other end of the spark plug wire to the coil that is being tested.
        3. Connect one end of another spark plug wire to the other coil towe, and connect the other end of the spark plug wire to ground.
        4. Crank the engine while you observe the spark tester. You should observe a crisp blue spark.
        5. Repeat the above steps for each coil.
    • If there is no spark at the coils, test for the following conditions:
       - The coils--Inspect for cracks, for carbon tracking/arcing, or for a secondary resistance value that is outside the specified range.

Coil Resistance
5,000-8,000 ohms (5K-8K ohms)

       - The spark plug wires--Inspect for signs of arcing or cross-firing, for cracks, for carbon tracking, for plug boot damage, for pinches, improper routing, or for a resistance value that is outside the specified range.

Spark Plug Wire Resistance
600 ohms per ft.

   Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is faulty.

       - A defective module
       - The ignition system wiring--Inspect for a loose ignition module feed or ground connection, or for damaged system wiring.
    • Remove spark plugs and inspect for the following:
       - Fouled plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned or damaged electrodes
       - Improper heat range or reach
    • If the spark plugs are gas or oil fouled, determine the cause of the fouling before you replace the spark plugs.

Additional Checks
    • Test the TCC operation. Refer to Torque Converter Diagnosis in Transaxle Diagnosis.
    • Test the exhaust system for possible restrictions:
       - Inspect the exhaust system for damaged or collapsed pipes.
       - Inspect the muffler for heat distress or for possible internal failure.
       - Test for a possible plugged Three-Way catalytic converter by checking the exhaust system backpressure. Refer to Restricted Exhaust System Check in Exhaust System .