GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2005 🢒 CTS 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 Hesitation, Sag, Stumble

Inspection/Tests

Action

DEFINITION: Momentary lack of response as the accelerator is pushed down. Can occur at any vehicle speed. Usually more pronounced when first trying to make the vehicle move, as from a stop. May cause the engine to stall if severe enough.

Preliminary
    • Refer to Important Preliminary Inspections Before Beginning in Symptoms - Engine Controls .
    • Search for bulletins.
    • Verify that the powertrain control module (PCM) grounds are clean, tight, and in the proper locations. Refer to Engine Controls Schematics .

Sensor/System
    • Inspect the manifold absolute pressure (MAP) sensor operation. Refer to DTC P0106 .
    • An extended travel brake switch that is mis-adjusted or an extended travel brake circuit that is open causes a perceived misfire under heavy load conditions from a stop. Use a scan tool in order to monitor the extended travel brake switch parameter.

Fuel System
    • Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis .
    • Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis .
    • Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Verify that both fuel injector fuses are not open. An open fuel injector fuse causes 4 ignition coils and 4 fuel injectors not to operate. Inspect the ignition coil circuits and the fuel injector circuits for an intermittent short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Replace the fuse.
    • Inspect the fuel injectors. Refer to Fuel Injector Solenoid Coil Test .
    • Inspect for the following that may cause the engine to run rich:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

       - Water intrusion in the heated oxygen sensor (HO2S) connector
       - Engine oil contaminated by fuel
       - An evaporative emission (EVAP) canister purge condition
       - Incorrect fuel pressure--Refer to Fuel System Diagnosis .
       - A leaking fuel pressure regulator--Refer to Fuel System Diagnosis .
       - Leaking fuel injectors--Refer to Fuel System Diagnosis .
       - Vacuum hoses that are split, kinked, improperly connected, or routed--Refer to Emission Hose Routing Diagram .
       - An air intake duct that is collapsed or restricted
       - An air filter that is dirty or restricted--Refer to Air Cleaner Element Replacement .
    • Inspect for the following conditions that may cause the engine to run lean:

Notice: Refer to Heated Oxygen and Oxygen Sensor Notice in the Preface section.

       - Water intrusion in the HO2S connector
       - An exhaust leak between the HO2S and the engine--Refer to Exhaust Leakage in Engine Exhaust.
       - Vacuum leaks
       - Incorrect fuel pressure--Refer to Fuel System Diagnosis .
       - Restricted fuel injectors--Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2 .
       - Fuel contamination--Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
       - Vacuum hoses that are split, kinked, improperly connected or routed--Refer to Emission Hose Routing Diagram .

Ignition System
    • Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water.
        Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. If a misfiring cylinder can be located, use the DTC P0300 table for diagnosis. Refer to DTC P0300 .
    • Test for proper ignition voltage output with the J 26792 Spark Tester . Refer to Electronic Ignition (EI) System Diagnosis for the procedure.
    • Remove the spark plugs and check for the following:
       - Correct heat range
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
       - Refer to Spark Plug Replacement .

Refer to Spark Plug Inspection and Ignition System Specifications .

    • Determine the cause of the fouling before replacing the spark plugs.
    • Inspect for loose ignition coil grounds. Refer to Electronic Ignition (EI) System Diagnosis .

Engine Cooling System

Inspect the engine thermostat for proper operation and for proper heat range. Refer to Thermostat Diagnosis in Engine Cooling.

Engine Mechanical

Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions:

    • A no start
    • A start and stall
    • Erratic performance

Additional Inspections

Inspect the generator output voltage. Refer to Diagnostic System Check - Vehicle in Vehicle DTC Information for the procedure. Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.