GM Service Manual Online
For 1990-2009 cars only

Definition: Engine delivers less than expected power.

Verify customer's vehicle has an actual problem by comparing it to a similar vehicle.

Check:

    • Air filter for restriction
    • Restricted fuel filter, contaminated fuel or improper fuel pressure
    • Exhaust system for restriction
    • Secondary voltage using a spark tester and jumper wires to check voltage output of the secondary coils
    • Generator charging output voltage. Repair if less than 13 volts or more than 16 volts with engine running and all accessories Off.
    • Verify engine has no mechanical knock or spark knock. If knock is present engine timing will be retarded and loss of power will result.
    • Engine valve timing, compression or worn camshaft. Refer to engine mechanical section.
    • Worn spark plugs