GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T65-E 🢒 Lack of Power, Sluggishness, or Sponginess

Lack of Power, Sluggish or Spongy

Checks

Action

DEFINITION: The engine delivers less than expected power. There is little or no increase in speed when the accelerator pedal is pushed down part way.

Preliminary Checks
    • Refer to Important Preliminary Checks.
    • Refer to Visual/Physical Checks.
    • Search for bulletins.

Fuel System Checks
    • Test the system fuel pressure. Refer to Fuel System Pressure Test (VIN K) . Refer to Fuel System Pressure Test (VIN 1) .
    • Test the fuel injectors using the following tests:
       -  Fuel Injector Balance Test .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Alcohol-in-Fuel Diagnosis .
    • 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 .

Sensor/System
    • Use a scan tool in order to inspect for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .
    • Test the EGR system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .
    • Inspect for a restricted air intake system. Refer to Air Intake System Description .

Ignition System
    • Test for proper ignition voltage output using the following steps:
        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 tower, 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 no spark is present at the coils, inspect for the following conditions:
       - The coil(s)--Inspect for cracks, for carbon tracking or arcing, or for a secondary resistance value 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, for 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 to locate an intermittent problem. The ignition components will arc to ground when a secondary component is faulty.

       - A defective module
       - The ignition system wiring--Inspect for loose ignition module feed or ground connections, or for damaged system wiring.
    • Remove the spark plugs and inspect for the following conditions:
       - 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.

Engine Mechanical
    • Excessive oil in combustion chamber--Inspect for leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
    • Low cylinder compression--Refer to Engine Compression Test in Engine Mechanical.
    • Incorrect basic engine parts--Inspect the following engine components:
       - The camshaft
       - The cylinder heads
       - The pistons
       - Other engine components, as applicable

Additional Checks
    • Inspect the exhaust system for possible restrictions--Check for the following conditions:
    • Inspect the exhaust system for damaged or collapsed pipes.
    • Inspect the mufflers for heat distress or for possible internal failure.
    • Check for a possible plugged three-way catalytic converter. Refer to Restricted Exhaust System Check in Engine Exhaust.
    • Check for proper TCC operation. Refer to Torque Converter Diagnosis in Automatic Transaxle -4T65-E.