GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1998 🢒 Savana 🢒 Engine 🢒 Engine Controls - 5.0L and 5.7L 🢒 Lack of Power, Sluggishness, or Sponginess

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 unit. Make sure the customer has an actual problem.
    • Remove the air filter and check for dirt or a restriction.
    • Check the transmission shift pattern and the downshift operation. Refer to Functional Test or Functional Test in Automatic Transmission.

Fuel System Checks
    • Check for a restricted fuel filter, contaminated fuel, or improper fuel pressure. Refer to Fuel System Diagnosis .
    • Perform the fuel injector balance test. Refer to Fuel Injector Balance Test .

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

Additional Checks
  1. Check the Control Module ground for being clean, tight and in their proper location.
  2. Check the EGR Valve for being open or partially open all the time. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis .
  3. Check the Torque Converter Clutch (TCC) operation. Refer Functional Test or Functional Test in Automatic Transmission.
  4. Check the A/C operation. Refer to Air Conditioning (A/C) Compressor Control Circuit Diagnosis .
  5. Check the generator output voltage. Refer to Charging System Check in Engine Electrical.
  6. Check the Knock Sensor (KS) system.

Engine Mechanical Check

Check the engine for the proper operation of the following items:

    • Engine compression
    • Valve timing
    • Improper or worn camshaft. Refer to Engine Mechanical.