Lack of Power, Sluggishness, or Sponginess

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Lack Of Power, Sluggishness, Or Sponginess

Checks	Action
DEFINITION: The engine delivers less than expected power. There is little or no increase in speed when partially applying the accelerator pedal.
Preliminary Checks	Refer to Diagnostic System Check - Vehicle in Vehicle DTC Information. Refer to Symptoms - Engine Controls . Compare the customers vehicle with a similar unit in order to determine if the customer has an actual problem. Remove the air filter element and check for dirt or restrictions. Check the air inlet duct for any blockage or restrictions. Check the transmission shift pattern and down-shift operation.
Sensor/System	Inspect the mass air flow (MAF) sensor operation. Run the engine to normal operating temperature. Turn OFF all accessories and observe the MAF sensor at idle with a scan tool. If the MAF sensor reading is more than 3.5 g/s refer to DTC P0101 .
Fuel System Checks	Check for a restricted fuel filter or incorrect fuel pressure. Check the fuel injectors. Perform the following procedures: The Fuel Injector Coil Test-Refer to Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Between 10-35 Degrees C (50-95 Degrees F) or to Fuel Injector Coil Test - Engine Coolant Temperature (ECT) Outside 10-35 Degrees C (50-95 Degrees F) . The Fuel Injector Balance Test-Refer to Fuel Injector Balance Test with Special Tool . Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Ignition System Checks	Check for the proper ignition voltage output with a J 26792 Spark Tester. See Special Tools . Inspect the spark plugs for correct operation and good ignition system performance. Refer to Spark Plug Inspection . Check the knock sensor (KS) and the sensor circuit shielding. A faulty knock sensor or signal interference could cause excessive retard of the ignition timing advance. Observe the spark parameter on a scan tool and compare with a known good vehicle. A typical value at 98 km/h (60 mph) with all engine accessories off is 26-32 degrees.
Exhaust System Checks	Check the exhaust system for a possible restriction. Refer to Restricted Exhaust in Engine Exhaust. Inspect the exhaust system for damaged or collapsed pipes. Inspect the muffler for heat distress or a possible internal failure.
Engine Mechanical Check	Check for any of the following engine mechanical problems: A low compression An incorrect valve timing An incorrect or worn camshaft Refer to Diagnostic Starting Point - Engine Mechanical in Engine Mechanical - 1.8L (LNK).
Additional Checks	If the loss of power is great above 6,000 RPM, inspect for the correct operation of the Rocker Arm Oil Control system. Refer to DTC P2647 . If there is a slight loss of power at wide open throttle (WOT), inspect for the correct operation of the Auxiliary Intake Air Control system. Refer to Auxiliary Intake Air System Diagnosis . Check the powertrain control module (PCM) grounds for being clean, tight, and in the proper locations. Refer to Engine Controls Schematics . Check the generator output voltage.