GM Service Manual Online
For 1990-2009 cars only

Checks

Action

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

Preliminary Checks

    • Refer to Symptoms .
    • Compare the customer's vehicle with a similar vehicle in order to determine the severity of the customer's concern.
    • Remove the air filter element and check for dirt or restrictions.
    • Check the transmission shift pattern and down shift operation.

Fuel System Checks

    • Check for a restricted fuel filter. Check for the correct fuel pressure. Refer to Fuel System Diagnosis .
    • Check for contaminated fuel or inferior quality fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System Checks

    • Check for adequate secondary ignition voltage with a J 26792 spark tester or an equivalent.
    • Check for the proper operation of the ignition control system. Check the ignition timing. Refer to Ignition Timing Adjustment .

Exhaust System Checks

    • Inspect the exhaust system for damaged or collapsed pipes.
    • Check the exhaust system for a possible internal restriction. Refer to Restricted Exhaust System Check .

Additional Checks

    • Check the PCM grounds for being clean, tight, and in the proper location. Refer to

PCM Power and Ground


Object Number: 61903  Size: FS
.
    • Check the EGR Valve for excessive flow or sticking open. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis .
    • Check the generator output voltage.

Engine Mechanical Check

Check for any of the following engine mechanical problems:

    • Low compression
    • Incorrect valve timing
    • Incorrect or worn camshaft

Refer to Engine Mechanical.