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For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2002 🢒 Impala 🢒 Engine 🢒 Engine Electrical 🢒 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 Important Preliminary Checks.
    • Refer to Visual/Physical Checks.
    • Search for bulletins.

Fuel System Checks
    • Test the system fuel pressure. Refer to Fuel System Diagnosis .
    • Test the fuel injectors using the following tests:
       - Refer to Fuel Injector Solenoid Coil Test .
       - Refer to Fuel Injector Balance Test with Tech 2 .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect 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 .
    • Inspect 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 .

Sensor/System
    • Use a scan tool in order to inspect for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .
    • Test the EGR system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .
    • Inspect for a restricted air intake system. Refer to Air Intake System Description .

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 theJ 26792 . Connect the other end of the spark plug wire to the coil being tested.
       - Connect another spark plug wire between the remaining tower of the coil being tested and ground.
       - Crank the engine while observing the J 26792 . A crisp blue spark should be observed.
       - Repeat the above steps for each coil.
    • If spark is not present at the coils, test for the following conditions:
       - Coils--Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified range

Coil Resistance
5,000-8,000 ohms

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

       - Spark plug wires--Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range.

Spark Plug Wire Resistance-Regular
3,000 ohms per foot

Spark Plug Wire Resistance-Police
600 ohms per foot

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

Engine Mechanical
    • Excess oil in combustion chamber--Inspect for leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical.
    • Low cylinder compression--Refer to Engine Compression Test in Engine Mechanical.
    •  Inspect for incorrect engine parts, such as the following basic components:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.

Refer to Symptoms - Engine Mechanical in Engine Mechanical.

Additional Checks
    • Inspect the exhaust system for possible restrictions. Inspect for the following:
       - The exhaust system for damaged or collapsed pipes.
       - The mufflers for heat distress or possible internal failure.
       - For possible plugged three-way catalytic converter--Refer to Restricted Exhaust in Engine Exhaust .
    • Check for proper TCC operation. Refer to Torque Converter Diagnosis in Automatic Transaxle -4T65-E.