Lack of Power, Sluggishness, or Sponginess

WARNING: This page is about a different car, the 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Inspections	Action
DEFINITION: The engine delivers less than expected power. Little increase in speed, or a total lack of acceleration when the accelerator pedal is pushed down part way.
Preliminary	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Inspect the engine control system grounds for being clean, tight, and in the correct locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Ensure the resistance between the engine control module (ECM) housing and the battery negative cable is less than 0.5 ohms. Verify that the ECM and ECM bracket fasteners are at the correct torque. Remove the air filter element and inspect for restrictions. Refer to Air Cleaner Element Replacement . Inspect the intake air duct and air cleaner outlet resonator for the following conditions: Restrictions Improperly installed hoses Leaks Collapsed hoses
Fuel System	Test for incorrect fuel system 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 (w/o Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (w/Special Tool) . Test the fuel injectors. Refer to Fuel Injector Coil Test . Test the items that cause an engine to run rich. For a rich condition, refer to DTC P2178 or DTC P2188 . Test the items that can cause an engine to run lean. For a lean condition, refer to DTC P2177 or DTC P2187 .
Sensor/System	Monitor the knock sensor (KS) system for excessive spark retard activity with a scan tool. Refer to Knock Sensor (KS) System Description , DTC P0327 or P0332 , andDTC P0328 or P0333 .
Ignition System	Inspect for the correct installation of the ignition coil seals. Incorrect installation may allow water to enter the spark plug area. Inspect for moisture and corrosion. Test for the correct ignition voltage output with a J 26792 Spark Tester. If you suspect an ignition system condition exists, refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following conditions: Incorrect heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to the following procedures: Spark Plug Replacement Ignition System Specifications Spark Plug Inspection If the spark plugs are gas, coolant or oil fouled, determine the cause before replacing the spark plugs. Refer to the following procedures: For diagnosis of a rich condition, refer to DTC P2178 or DTC P2188 . For diagnosis of coolant contaminated spark plugs, refer to Loss of Coolant in Engine Cooling. For diagnosis of oil fouled spark plugs, refer to Oil Consumption Diagnosis in Engine Mechanical - 3.6L (LY7). Inspect the crankshaft position (CKP) sensor for the correct resistance. The sensor resistance may be out of range after a hot soak. Measure that the resistance remains within 700-1,200 ohms at all temperatures. Inspect the spark plug boots and terminals for burning or micro-arcing, corrosion, and damage to the insulation.
Engine Mechanical	Inspect for the following engine mechanical conditions: Excessive oil in combustion chamber or leaking valve seals Incorrect cylinder compression Sticking or leaking valves Worn camshaft lobes Camshaft timing Broken valve springs Excessive carbon buildup in the combustion chambers-Clean the chambers with top engine cleaner. Follow the instructions on the can. For more information, refer to the following procedures in Engine Mechanical - 3.6L (LY7): Oil Consumption Diagnosis Engine Compression Test Camshaft Timing Drive Chain Alignment Diagram Setting Camshaft Timing Symptoms - Engine Mechanical Inspect the following components for incorrect basic engine parts: Camshafts Cylinder heads Pistons, connecting rods, or bearings. Refer to the following procedures in Engine Mechanical - 3.6L (LY7): Camshaft Timing Drive Components Cleaning and Inspection Camshaft Cleaning and Inspection Cylinder Head Cleaning and Inspection Piston, Connecting Rod, and Bearings Cleaning and Inspection
Additional	Inspect the following exhaust system components: The exhaust system for damage. The mufflers for heat distress or possible internal failure. The catalytic converter(s) for restrictions. For more information, refer to Symptoms - Engine Exhaust in Engine Exhaust. Test for the correct operation of the intake manifold runner control solenoid. Refer to Intake Manifold Runner Control System Diagnosis . Test the transmission torque converter clutch (TCC) for the correct operation. Refer to Torque Converter Diagnosis Procedure in Automatic Transmission/Transaxle - 4T65-E. Test for other transmission related faults that might cause the transmission to operate in a default mode. Refer to Symptoms - Automatic Transmission in Automatic Transmission/Transaxle - 4T65-E.