Lack of Power, Sluggishness, or Sponginess. Pontiac Firebird 2002

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 2002 🢒 Firebird 🢒 Engine 🢒 Engine Electrical 🢒 Lack of Power, Sluggishness, or Sponginess

Lack of Power, Sluggish or Spongy

Checks

Action

DEFINITION: The engine delivers less than expected power. When the accelerator pedal is pushed down part way, there is little or no increase in the speed.

Preliminary Checks

•	Refer to Important Preliminary Checks Before Starting in Symptoms - Engine Controls .

•	Search for bulletins.

•	Inspect the powertrain control module (PCM) grounds. Ensure that they are clean, tight, and in the proper locations. Refer to Engine Controls Schematics .

•	Remove the air filter element. Inspect for dirt or for restrictions. Refer to Air Cleaner Element Replacement and replace as necessary.

Fuel System Checks

•	Inspect both injector fuses for being open. An open injector fuse causes 4 ignition coils and 4 injectors to not operate. Replace the fuse. Inspect the ignition coil circuits. Inspect the injector circuits for an intermittent short to ground.

•	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis .

•	Test for a restricted fuel filter. Refer to Fuel System Diagnosis .

•	Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Inspect for conditions that cause an engine to run rich, with the long-term fuel trim near -13 percent. For a rich condition, refer to DTC P0132 or P0152 .

•	Inspect for conditions that can cause an engine to run lean, with a long-term fuel trim near 24 percent. For a lean condition, refer to DTC P0131 or P0151 .

Sensor/System

Use a scan tool in order to monitor the KS system for excessive spark retard activity. Refer to Knock Sensor (KS) System Description .

Ignition System

•	Inspect both injector fuses for being open. An open injector fuse causes 4 ignition coils and 4 injectors not to operate. Replace the fuse. Inspect the ignition coil circuit. Inspect the injector circuits for an intermittent short to ground.

•	Wet the secondary ignition system with water from a spray bottle. Wetting the secondary ignition system may help to locate damaged or deteriorated components. When you apply the water, look and listen for arcing or for misfiring.

•	Test for proper ignition voltage output with spark tester J 26792 . Refer to Electronic Ignition (EI) System Diagnosis .

•	Remove the spark plugs and inspect for the following conditions:

-	The correct heat range

Wet plugs

Cracks

Wear

-	Improper gap

-	Burned electrodes

-	Heavy deposits

-	Refer to Spark Plug Inspection in Engine Electrical.

•	An improper spark plug gap causes a driveability condition. Gap the spark plugs using a wire gauge gap tool. Refer to Spark Plug Wire Replacement .

•	Before you replace the spark plugs, determine the cause of the fouling.

-	Gas fouling--Refer to DTC P0172 or P0175 .

-	Oil fouling--Refer to Oil Consumption Diagnosis in Engine Mechanical-5.7L.

-	Coolant fouling--Refer to Loss of Coolant in Engine Cooling.

•	Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .

Engine Mechanical

•

Ensure that the engine coolant temperature is not above 132°C (270°F). This condition causes the PCM to operate in Engine Coolant Over Temperature-Fuel Disabled Mode. While in Engine Coolant Over Temperature-Fuel Disabled Mode, the PCM turns the fuel OFF to 4 cylinders at a time in order to keep the engine temperatures from reaching damaging levels. The customer perceives the Engine Coolant Over Temperature-Fuel Disabled Mode as a lack of power, a miss, or a rough idle. If the engine operates in the Engine Coolant Over Temperature-Fuel Disabled Mode, refer to Engine Overheating in Engine Cooling.

•	Excessive oil in the combustion chamber caused by leaking valve seals--Refer to Oil Consumption Diagnosis in Engine Mechanical-5.7L.

•	Low cylinder compression--Refer to Engine Compression Test in Engine Mechanical-5.7L.

•	Incorrect basic engine parts-Inspect the following components:

-	The camshaft

-	The cylinder heads

-	The pistons

•	Refer to Symptoms - Engine Mechanical in Engine Mechanical-5.7L.

Additional Checks

•	Inspect the exhaust system for possible restrictions. Inspect for the following conditions:

-	Inspect the exhaust system for damaged or collapsed pipes. Refer to Restricted Exhaust in Engine Exhaust.

-	Inspect the exhaust manifold for a collapsed inner wall. Refer to Exhaust Manifold Cleaning and Inspection in Engine Mechanical-5.7L.

-	Inspect the mufflers for heat distress, or for possible internal failure.

-	Inspect for possible plugged 3-way catalytic converters by comparing the exhaust system back pressure on each side of the engine. Test the back pressure by removing the AIR check valves near the exhaust manifolds or near the heated oxygen sensors. Refer to Restricted Exhaust in Engine Exhaust.

•	Test the Transmission Torque Converter Clutch (TCC) operation. Refer to Diagnostic Starting Point - Automatic Transmission in Automatic Transmission-4L60-E.