Lack of Power, Sluggishness, or Sponginess. GMC Truck Envoy

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2007 🢒 Envoy - 2WD 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 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 .