GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2003 🢒 CTS - RHD 🢒 Engine 🢒 Engine Electrical 🢒 Lack of Power, Sluggishness, or Sponginess

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 module (ECM) grounds for being clean, tight and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
    • Remove the air filter element and inspect for dirt or for being restricted.
    • Inspect the intake air ducts for the following conditions:
       - Restrictions
       - Improperly installed hoses
       - Leaks
       - Collapsed hoses

Fuel System
    • Inspect the fuel system. Refer to Fuel System Diagnosis .
    • Test for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool , and Fuel Injector Solenoid Coil Test .
    • Inspect the items which can cause an engine to run rich, long term fuel trim near -13 percent. For a rich condition, refer to DTC P0172 or P0175 .
    • Inspect the items that can cause an engine to run lean, long term fuel trim near 23 percent. For a lean condition, refer to DTC P0171 or P0174 .

Sensor/System
    • Monitor the knock sensor (KS) system for excessive spark retard activity with a scan tool. Refer to Detonation/Spark Knock .
    • Verify the proper operation of the throttle actuator control (TAC) system by performing the following procedures:
       - Observe the throttle position (TP) sensor angle and the accelerator pedal position (APP) sensor angle with a scan tool.
       - Turn the key ON, with the engine OFF.
       - Slowly depress the accelerator pedal to wide open throttle (WOT), then slowly return the pedal to the rest position.
       - The TP sensor angle and the APP sensor angle should increase to nearly 100 percent as the pedal is depressed and decrease as the pedal is released. A verification of the entire TAC system will be performed. If the TP sensor angle and the APP sensor angle values do not increase as the pedal is depressed, verify the APP sensor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Ignition System
    • Test for proper ignition system operation. Refer to Electronic Ignition (EI) System Diagnosis .
    • Test for secondary ignition leakage. Refer to Electronic Ignition (EI) System Diagnosis .
    • Remove the spark plugs and inspect for the following conditions:
       - Correct heat range
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
    • Determine the cause of the fouling before replacing the spark plugs if the spark plugs are gas, coolant or oil fouled. Refer to Spark Plug Inspection . Once you determine the cause of the fouling, refer to one of the following procedures:
       - For diagnosis of a rich condition, refer to DTC P0172 or P0175 .
       - 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.

Engine Mechanical
    • Excess oil in combustion chamber due to leaking valve seals--Refer to Oil Consumption Diagnosis in Engine Mechanical.
    • Inspect for incorrect camshaft timing. Refer to Timing Belt Timing Adjustment in Engine Mechanical.
    • Inspect the following components for incorrect basic engine parts:
       - Camshafts--Refer to Camshaft and Bearings Cleaning and Inspection in Engine Mechanical.
       - Cylinder heads--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
       - Pistons, connecting rods or bearings--Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical.

Additional
    • Inspect the following components of the exhaust system for possible restrictions:
       - The exhaust system for physical damage
       - The mufflers for heat distress or possible internal failure
       - The catalytic converters for possible plugged pipes by comparing the exhaust system back pressure on each side of engine--Refer to Restricted Exhaust in Engine Exhaust.
    • Test for proper operation of the intake manifold tuning valve and the intake manifold runner control valve. Refer to Intake Manifold Runner Control System Diagnosis .
    • Test the transmission torque converter clutch (TCC) for proper operation. Refer to Torque Converter Diagnosis in Automatic Transmission.
    • Test for other transmission related faults that might cause the transmission to operate in a default mode. Refer to Diagnostic System Check - Automatic Transmission in Automatic Transmission.