GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2004 🢒 Kodiak C-Series (Conventional) C4/C5 🢒 Engine 🢒 Engine Controls - 6.6L (LB7) 🢒 Lack of Power, Sluggishness, or Sponginess

Inspection

Action

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

Preliminary Inspection
    • Refer to Symptoms - Engine Controls .
    • Compare the vehicle with a similar unit. Ensure the vehicle has an actual problem.
    • Compare the scan tool data with the scan tool data list while the engine is idling. Refer to Scan Tool Data List .
    • Ensure that the power take off (PTO) switch is in the OFF position.
    • Remove the air filter and inspect for dirt, or for air ducts being plugged or leaking. Repair or replace as necessary.
    • Inspect for a proper transmission operation.
    • Inspect the engine oil level and quality.

Fuel System Inspection
    • Inspect the fuel supply to the fuel injection pump. Refer to Fuel System Diagnosis .
    • Observe the actual vs. desired fuel rail pressure with the engine idling.
    • Start the engine and command the fuel pressure to 160 MPa with a scan tool. If the actual fuel pressure does not reach 160 MPA, go to Fuel System Diagnosis - High Pressure Side .
    • Inspect for restricted or plugged fuel injectors. Refer to Fuel Injector Balance Test with Tech 2 .

Exhaust System Inspection

Inspect the exhaust system for a possible restriction. Refer to Restricted Exhaust in Engine Exhaust.

Air Intake System Inspection
    • Inspect for an air leak or restriction in the air inlet ducts or the intake manifold. Refer to DTC P0234 .
    • Inspect for an air leak in the charge air cooler.
    • Inspect the charge air cooler for a restriction.
    • Inspect for a worn or damaged turbo charger turbine wheel, shaft or compressor wheel.
    • Inspect for a skewed mass air flow (MAF) sensor. Refer to Scan Tool Data List .

Engine Mechanical Inspection

Inspect the engine for the following:

    • Low compression--Refer to Engine Compression Test in Engine Mechanical-6.6L.
    • Improper valve timing
    • Improper or worn camshaft--Refer to Camshaft and Bearings Cleaning and Inspection in Engine Mechanical-6.6L.

Refer to Engine Compression Test in Engine Mechanical-6.6L.

Additional Inspection
    • Inspect the control module grounds for being clean, tight, and in their proper location.
    • Inspect the torque converter clutch (TCC) operation.
    • Inspect the air conditioning system for proper operation. Refer to Symptoms - HVAC Systems - Manual in HVAC Systems-Manual.
    • Inspect the generator output voltage. Refer to Charging System Test in Engine Electrical.