GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 1999 🢒 S/T Isuzu - 2WD 🢒 Engine 🢒 Engine Controls - 2.2L 🢒 Lack of Power, Sluggishness, or Sponginess

Lack of Power, Sluggish or Spongy

Checks

Action

DEFINITION: Engine delivers less than expected power. Little or no increase in speed when the accelerator pedal is pushed down part way.

Preliminary Checks
    • Refer to Symptoms .
    • Search for service bulletins.
    • Check and compare the customer's vehicle to a similar vehicle. Make sure the customer's vehicle has an actual problem.
    • Check the air cleaner filter for dirt or being plugged.

Fuel System Checks
    • Check the system fuel pressure. Refer to Fuel System Diagnosis .
    • Check the fuel injectors. Refer to Fuel Injector Balance Test .
    • Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check items which can cause an engine to run rich (long term fuel trim is significantly in the negative range). Refer to Diagnostic Aids for DTC P0172 Fuel Trim System Rich .
    • Check items that can cause an engine to run lean (long term fuel trim is significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 Fuel Trim System Lean .

Sensor/System
    • Using a scan tool, monitor KS system for excessive spark retard activity. Refer to DTC P0325 Knock Sensor (KS) Circuit .
    • Check for proper operation of the MAP sensor.
    • Check for proper operation of the TP sensor.
    •  Check for a restricted air intake system.

Ignition System
    • Check for proper ignition voltage output with the J 26792 spark tester or equivalent.
    • Check the spark plugs for the following conditions:
       - Check for wet or fuel fouled spark plugs.
       - Check for cracks on the spark plugs.
       - Check for wear.
       - Check for improper spark plug gap.
       - Check for burned electrodes or heavy deposits.
    • If the spark plugs are fuel or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
    • Check the Ignition Control Module (ICM) for proper ground connection.
    • Check the ignition coils for cracks or carbon tracking.
    • Check the spark plug wires for proper resistance and condition.

Engine Mechanical
    • Check the engine for the following engine mechanical problems:
       - Check for low compression.
       - Check for correct valve timing.
       - Check for leaking cylinder head gasket.
       - Check for a worn or a incorrect camshaft.
    • Refer to the Engine Mechanical portion of the service manual.

Additional Checks
    • Check for proper operation of the TCC. Refer to Automatic Transmission Diagnosis .
    • Check the exhaust system for a possible restriction:
       - Inspect the exhaust system for damaged or for possible collapsed pipes.
       - Inspect the muffler for heat distress or for possible internal failure.
       - Check for possible plugged Three-Way catalytic converter. Refer to Restricted Exhaust System Check or Exhaust System .
    • Check the vacuum lines for kinks or leaks.
    • Check the generator output voltage. Repair the generator if the output voltage is less than 11 volts or more than 16 volts.
    • Check the A/C system operation. The A/C clutch should cut out at the Wide Open Throttle (WOT) position.
    • If all procedures have been completed and no malfunctions have not been found, review and inspect the following items:
       - Visually and physically inspect all electrical connections within the suspected circuit and/or systems.
       - Check scan tool data.