GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 1999 🢒 Firebird 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Surges/Chuggles

Checks

Action

DEFINITION: Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the accelerator pedal position.

Preliminary
    • Refer to Important Preliminary Checks Before Starting in Symptoms .
    • Search for bulletins.
    • Inspect the PCM grounds for being clean, tight and in the proper locations. Refer to Engine Controls Schematics .
    • Be sure the driver understands the operation of the Transmission Torque Converter Clutch (TCC) and A/C compressor operation as explained in the owners manual. Inform the customer how the TCC and the A/C clutch operates.

Sensor/System
    • Monitor the Heated Oxygen Sensors (HO2S) voltages. The Heated Oxygen Sensors (HO2S) should respond quickly to different throttle positions. If the sensors do not respond, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white powdery coating and result in a high but false signal voltage (rich exhaust indication). The PCM then reduces the amount of fuel delivered to the engine causing a severe driveability condition. For more information, Refer to Information Sensors/Switches Description .
    • Inspect the MAF sensor connections. Repair or replace terminals. Refer to Repairing Connector Terminals in Wiring Systems.

Fuel System
    • Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Test for a restricted fuel filter. Refer to Fuel System Diagnosis .
    • Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect that each injector harness is connected to the correct injector/cylinder according to the firing order (firing order: 1-8-7-2-6-5-4-3). Relocate injector harnesses as necessary.
    • Inspect the items that cause an engine to run rich (long term fuel trim near -13%). For a rich condition, refer to DTC P0132 HO2S Circuit High Voltage Bank 1 Sensor 1 and DTC P0152 HO2S Circuit High Voltage Bank 2 Sensor 1 .
    • Inspect items that can cause an engine to run lean (long term fuel trim near 24%). For a lean condition, refer to DTC P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1 and DTC P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1 .

Ignition System
    • Wet down the secondary ignition system with water from a spray bottle. Wetting down the secondary ignition system may help locate damaged or deteriorated components. Look/listen for arcing or misfiring as you apply the water.
    • Test for proper ignition voltage output with spark tester J 26792 . Refer to Electronic Ignition (EI) System Diagnosis .
    • Remove the spark plugs and inspect for the following:
       - Correct heat range; refer to Spark Plug Usage in Engine Electrical.
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits

Refer to Spark Plug Visual Diagnosis in Engine Electrical.

    • An improper spark plug gap causes a driveability condition. Gap the spark plugs using a wire gauge gap tool (J 41319). Refer to Spark Plug Replacement in Engine Electrical.
    • Determine the cause of the fouling before replacing the spark plugs. If the spark plugs are gas fouled, refer to DTC P0172 Fuel Trim System Rich Bank 1 or DTC P0175 Fuel Trim System Rich Bank 2 . If the spark plugs are coolant or oil fouled, refer to Oil Consumption Diagnosis in Engine Mechanical-5.7L or Loss of Coolant in Engine Cooling.
    • Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .

Engine Mechanical

Ensure that the engine coolant temperature is not above 132°C (270°F). This condition causes the PCM to operate in Engine Coolant Over temperature-Fuel Disabled Mode. While in Engine Coolant Over temperature-Fuel Disabled Mode, the PCM turns fuel off to four cylinders at a time to keep engine temperatures from reaching damaging levels. The customer perceives Engine Coolant Over temperature-Fuel Disabled Mode as a lack of power, miss, or rough idle. If the engine operates in Engine Coolant Over temperature-Fuel Disabled Mode, refer to Engine Overheating in Engine Cooling.

Additional Checks
    • Visually/physically inspect vacuum hoses for splits, kinks, and proper connections and routing as shown on Vehicle Emission Control Information label. Refer to Emission Hose Routing Diagram .
    • Test the Transmission Torque Converter Clutch (TCC) operation. A TCC applying too soon can cause the engine to spark knock. Refer to Functional Test in Automatic Transmission 4L60-E.