GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2005 🢒 VUE - AWD 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Lack of Power, Sluggishness, or Sponginess

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 Diagnostic System Check - Vehicle .
    • Refer to Symptoms - Engine Controls .
    • Compare the customers vehicle with a similar unit in order to determine if the customer has an actual condition.
    • Remove the air filter element and check for dirt or restrictions.
    • Check the air inlet duct for any blockage or restrictions.
    • Check the transmission shift pattern and down-shift operation.

Sensor/System

Inspect the throttle actuator control (TAC) system for correct operation. Refer to Throttle Actuator Control (TAC) System Description .

Fuel System Checks
    • Test for a restricted fuel filter or incorrect fuel pressure.
    • Test the fuel injectors. Perform the following procedures:
       - The Fuel Injector Coil Test--Refer to Fuel Injector Solenoid Coil Test .
       - The Fuel Injector Balance Test--Refer to Fuel Injector Balance Test with Tech 2 .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Ignition System Checks
    • Test for the proper ignition voltage output with a J 26792 Spark Tester.
    • Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection .
    • Inspect the knock sensor (KS) and the sensor circuit shielding. A faulty knock sensor or signal interference could cause excessive retard of the ignition timing advance. Observe the spark parameter on a scan tool and compare with a known good vehicle.

Exhaust System Checks
    • Test 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.

Engine Mechanical Check
    • Check for any of the following engine mechanical problems:
       - A low compression
       - An incorrect valve timing
       - An incorrect or worn camshaft
    • Refer to Symptoms - Engine Mechanical .

Additional Checks
    • If the loss of power is above 4,200 RPM, inspect for the correct operation of the rocker arm oil control system. Refer to DTC P2646 .
    • Check the powertrain control module (PCM) grounds for being clean, tight, and in the correct locations. Refer to Engine Controls Schematics .
    • Check the generator output voltage.