GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Rainier 🢒 Engine 🢒 Engine Controls - 4.2L 🢒 Lack of Power, Sluggishness, or Sponginess

Inspections

Action

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

Preliminary
    • Refer to Symptoms - Engine Controls .
    • Compare the customer vehicle with a similar unit. Verify the customer concern.
    • Remove the air filter and check for dirt or a restriction.
    • Inspect the transmission shift pattern and the downshift operation. Refer to Symptoms - Automatic Transmission .

Fuel System
    • Inspect 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 Diagnosis .

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

Additional
    • Inspect the control module grounds for being clean, tight, and in their proper location. Refer to Ground Distribution Schematics.
    • Inspect the torque converter clutch (TCC) operation. Refer to Torque Converter Diagnosis .
    • Inspect the A/C compressor clutch operation.
    • Monitor the knock sensor (KS) system for retarded timing.

Engine Mechanical

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

    • Engine compression--Refer to Engine Compression Test .
    • Valve timing
    • Improper or worn camshaft--Refer to Camshafts Cleaning and Inspection .