GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Firebird 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Lack of Power, Sluggishness, or Sponginess

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 the Symptoms .
    • Search for bulletins.

Fuel System
    • Test the following items:
    • Fuel pressure.
       - Fuel injectors.
       - Contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
       - Test 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 Bank 1 .
       - Test 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 Bank 1 .

Sensor/System
    • Using a scan tool, monitor KS system for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .
        If knock retard is above 10-12 degrees, disconnect the knock sensor and ground the sensor harness connector. Monitor the knock retard on the scan tool, there should be no knock retard present. If knock retard is still present, the PCM is malfunctioning. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming .
    • Test the EGR valve for a stuck open pintle. Refer to Exhaust Gas Recirculation Valve Replacement .
    • Inspect for a restricted intake duct or a dirty air cleaner element. Refer to Air Cleaner Element Replacement .

Ignition System
    • Test for proper ignition voltage output using the following steps:
       - Clip the J 26792 spark tester to engine ground.
       - Connect one end of a spark plug wire to the spark tester, leave the other end of the spark plug wire to the coil being tested.
       - Connect one end of another spark plug wire to the other coil tower, connect the other end of the spark plug wire to ground.
       - Crank the engine while observing the spark tester, a spark should be observed.
       - Repeat the above steps for each coil.
    • If adequate spark is not present at the coils, test for the following conditions:
    • Coils - Cracks, carbon tracking/arcing, or a resistance value outside the specified range.

Coil Secondary Resistance
5000 - 8000 ohms (5K - 8K ohms)

    • Spark Plug wires - Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, incorrect routing, or a resistance value more than the specified value.

Spark Plug Wires Resistance
3280-4921 ohms/meter(1000-1500 ohms/ft).

       Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is malfunctioning.

    • Malfunctioning ignition control module.
    • Ignition System Wiring - Loose ignition module feed or ground connection, or damaged system wiring.
    • Remove spark plugs and inspect for the following conditions:
       - Fouled plugs
       - Cracks
       - Wear
       - Incorrect gap
       - Burned or damaged electrodes
       - Incorrect heat range
    • If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Mechanical
    • Excessive oil in combustion chamber-Leaking valve seals.
    • Low cylinder compression.
    • For incorrect basic engine parts. Inspect the following:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.
    •  Refer to Base Engine Misfire Diagnosis in Engine Mechanical.

Additional Tests
    • Test the exhaust system for a possible restriction.
    • Inspect the exhaust system for damaged or collapsed pipes.
    • Inspect the muffler for heat distress or possible internal failure.
    • Test for a plugged three-way catalytic converter. Refer to Restricted Exhaust System Check .
    • Test for proper TCC operation. Refer to A Diagnostic Starting Point in 4L60E Automatic Transmission.