GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2002 🢒 Sunfire 🢒 Engine 🢒 Engine Electrical 🢒 Lack of Power, Sluggishness, or Sponginess

Lack of Power, Sluggish or Spongy

Checks

Action

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

Preliminary Checks
    • Refer to Symptoms - Engine Controls .
    • Search for the service bulletins.
    • Check and compare the customer's vehicle to a similar vehicle. Ensure that the customer's vehicle has an actual problem.
    • Check the air cleaner filter for dirt or for restrictions.

Fuel System Checks
    • Check the fuel system pressure. Refer to Fuel System Diagnosis .
    • Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check items which can cause an engine to run rich, where the long-term fuel trim is significantly in the negative range. Refer to Diagnostic Aids for DTC P0172 .
    • Check for conditions that can cause an engine to run lean, where the long-term fuel trim is significantly in the positive range. Refer to Diagnostic Aids for DTC P0171 .
    • Check the throttle linkage and the throttle cables in order to ensure that the throttle plate opens fully.

Sensor/System
    • Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity.
    • Check for proper operation of the manifold absolute pressure (MAP) sensor.
    • Check for proper operation of the throttle position (TP) sensor.
    • Check for proper operation of the oxygen sensor 1 (O2S) 1.
    •  Check for a restricted air intake system.

Ignition System
    • Check for proper ignition voltage output with the J 36012-A Spark Plug Jumper Wires and with a J 26792 Spark Tester or equivalent.
    • Check the spark plugs for the following conditions:
       - Wet or fuel fouled spark plugs
       - Cracks on the spark plugs
       - Wear
       - Improper spark plug gap
       - Burned electrodes or heavy deposits
       - Heavy deposits
    • If the spark plugs are fuel or oil-fouled, determine the cause of the fouling before you replace the spark plugs.
    • Check the ignition control module (ICM) for proper ground connection.
    • Check the ignition coils for cracks or for carbon tracking.

Engine Mechanical

Check the engine for the following engine mechanical problems:

    • Low compression--Refer to Engine Compression Test in Engine Mechanical 2.4L.
    • Correct valve timing--Refer Symptoms - Engine Mechanical in Engine Mechanical 2.4L.
    • Check for leaking cylinder head gasket. Refer to Engine Compression Test in Engine Mechanical 2.4L.
    • Check for a worn camshaft, or for an incorrect camshaft. Refer to Symptoms - Engine Mechanical in Engine Mechanical 2.4L.

Additional Checks
    • Check for proper operation of the transaxle and the torque converter clutch (TCC). Refer to Road Test in Automatic Transmission 4T40-E/4T45-E.
    • Check the exhaust system for a possible restriction:
       - Inspect the exhaust system for damaged or for possible collapsed pipes.
       - Inspect the muffler for heat distress or for possible internal failure.
       - Check for possible plugged three-way catalytic converter. Refer to Restricted Exhaust in Engine Exhaust.
    • Check the vacuum lines for kinks or leaks.
    • Check the generator output voltage. Repair the generator if the output voltage is less than 11 volts or more than 16 volts.
    • Check the A/C system operation. The A/C clutch should cut out at the wide open throttle (WOT) position.
    • If all procedures have been completed and no malfunctions have not been found, review and inspect the following items:
       - Visually and physically inspect all electrical connections within the suspected circuit and/or systems.
       - Check scan tool data. Refer to Scan Tool Data List .