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For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2003 🢒 Grand Am 🢒 Engine 🢒 Engine Electrical 🢒 Lack of Power, Sluggishness, or Sponginess

Lack of Power, Sluggish or Spongy

Inspection/Tests

Action

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

Preliminary Inspections
    • Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls .
    • Search for bulletins.
    • Inspect the powertrain control module (PCM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
    • Remove the air filter element and inspect for dirt or for restrictions. Refer to Air Cleaner Element Replacement and replace as necessary.

Fuel System
    • Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
    • Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

Sensor/System
    • Inspect for the following that may cause the engine to run rich:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

       - Any water intrusion in the HO2S connector
       - The engine oil contaminated by fuel
       - An EVAP canister purge condition
       - Incorrect fuel pressure--Refer to Fuel System Diagnosis .
       - A leaking fuel pressure regulator--Refer to Fuel System Diagnosis .
       - A leaking fuel injectors--Refer to Fuel System Diagnosis .
       - Any vacuum hoses that are split, kinked, or improperly connected
       - An air intake duct that is collapsed or restricted--Refer to Air Cleaner Outlet Resonator Replacement .
       - An air filter that is dirty or restricted--Refer to Air Cleaner Element Replacement .
    • Inspect for the following conditions that may cause the engine to run lean:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

       - Any water intrusion in the HO2S connector
       - An exhaust leak between the HO2S and the engine--Refer to Restricted Exhaust in Engine Exhaust.
       - Any vacuum leaks
       - Incorrect fuel pressure--Refer to Fuel System Diagnosis .
       - Any restricted fuel injectors--Refer to Fuel System Diagnosis .
       - Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
       - Any vacuum hoses that are split, kinked, or improperly connected
    • Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Scan Tool Data List .

Ignition System
    • In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures:
       -  Spark Plug Inspection
       -  Spark Plug Replacement
    • Remove spark plugs and inspect for the following conditions:
       - Correct heat range
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
       - Verify that the spark plugs are of the correct type.
    • Inspect for proper ignition voltage output with the J 26792 HEI Spark Tester.
    • An improper spark plug gap will cause a driveability condition. Gap the spark plugs using a wire gage gap tool.
    • Determine the cause of the fouling before replacing the spark plugs.
    • Inspect for damaged or misaligned spark plug boots.
    • Inspect the electronic ignition (EI ) module for proper ground connection.
    • Monitor the Misfire Current Counters while driving the vehicle in the conditions that the symptom occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .

Engine Mechanical
    • Inspect for incorrect camshaft timing.
    • Inspect for excessive oil in the combustion chambers and leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
    • Test for low cylinder compression. Refer to Engine Compression Test in Engine Mechanical.
    • Inspect for incorrect basic engine parts, including the following components:
       - The camshaft--Refer to Camshaft Cleaning and Inspection in Engine Mechanical.
       - The cylinder heads--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
       - The pistons, etc.--Refer to Piston, Connecting Rod, and Bearing Installation in Engine Mechanical.

Additional Inspections
    • Inspect the exhaust system for the following possible restrictions:
       - The exhaust system for damaged or collapsed pipes
       - The mufflers for heat distress or internal failure
       - Refer to Restricted Exhaust in Engine Exhaust
    • Inspect the transmission torque converter clutch (TCC) for proper operation. Refer to Torque Converter Diagnosis in Automatic Transaxle 4T40-E/ 4T45-E.