GM Service Manual Online
For 1990-2009 cars only

Checks

Action

DEFINITION: The engine delivers less than the expected power. There is little or no increase in speed when partially applying the accelerator pedal.

Preliminary Checks

    â€¢ Refer to Symptoms .
    â€¢ Compare the vehicle with a similar unit. Make sure that the vehicle has an actual problem.
    â€¢ Remove the air filter.
    â€¢ Check for dirt, or for air ducts being plugged. Clean and replace if necessary.
    â€¢ Inspect the transmission shift pattern and the down shift operation.
    â€¢ Check the fuel quality. Refer to Specific Gravity Testing .
    â€¢ Check the engine oil level and quality.

Fuel System Checks

    â€¢ Check the fuel supply to the injection pump and the fuel return from the injection pump. Refer to Fuel Supply System Check .
    â€¢ Check the fuel pump operation. Refer to Fuel Supply System Check .
    â€¢ Check for malfunctioning fuel injection nozzles. Refer to Injection Nozzle(s) Diagnosis .

Exhaust System Checks

    â€¢ Check the exhaust system for a possible restriction. Refer to Exhaust Systems.
    â€¢ Inspect the exhaust system for damaged or collapsed pipes.

Air Intake System Checks

    â€¢ Check for an air leakage or a restriction in the air inlet ducts or the intake manifold.
    â€¢ Check for a worn or a damaged turbo charger turbine wheel, shaft or compressor wheel.

Engine Mechanical Check

Check the engine for the following:

    â€¢ Low compression
    â€¢ Improper valve timing
    â€¢ Improper or worn camshaft

Additional Checks

    â€¢ Check the control module grounds for being clean, tight, and in their proper location.
    â€¢ Check the torque Converter Clutch (TCC) operation.
    â€¢ Check the A/C operation. Refer to A/C Systems.
    â€¢ Check the generator output voltage. Repair if less than 9 or more than 16 volts.