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

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2003 🢒 Jimmy - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 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 - 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. Refer to Air Cleaner Element Replacement .

•	Check the transmission shift pattern and the downshift operation. Refer to Diagnostic Starting Point - Automatic Transmission 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 with Tech 2 .

Exhaust System Checks

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

Additional Checks

•	Check the control module grounds for being clean, tight, and in their proper location.

•	Check the torque converter clutch (TCC) operation. Refer to Diagnostic Starting Point - Automatic Transmission in Automatic Transmission.

•	Check the A/C operation. Refer to HVAC Compressor Clutch Does Not Engage or HVAC Compressor Clutch Does Not Disengage in HVAC-Manual.

•	Check the generator output voltage. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical.

•	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