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For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1999 🢒 Cutlass 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 Hesitation, Sag, Stumble

Hesitation, Sag, Stumble

Checks

Action

DEFINTION: 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 sign. May cause the engine to stall if severe enough.

Preliminary
    • Refer to Symptoms .
    • Search for service bulletins.

Sensor/System
    • Check the EGR valve for a stuck open pintle.
    • Check for proper operation of the MAP Sensor. Refer to Manifold Absolute Pressure Sensor Output Diagnosis .
    • Check for proper operation of the TP sensor.
    • Check for proper operation of the ECT sensor.
    • Check the Oxygen sensor (O2S 1). The O2S 1 should respond quickly to different throttle positions. If not, check the O2S 1 for silicon or other contaminants from fuel or the use of improper RTV sealant. The sensor may have a white powdery coating. Silicon contamination causes a high but false O2S 1 signal voltage (rich exhaust indication). The PCM will reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Refer to Oxygen sensor in Information Sensors/Switches Description .

Fuel System
    • Check the fuel pressure. Refer to Fuel System Diagnosis .
    • Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check the fuel injectors. Refer to Fuel Injector Balance Test .
    • Check items which can cause an engine to run rich (long term fuel trim is significantly in the negative range). Refer to Diagnostic Aids for DTC P0172 Fuel Trim System Rich .
    • Check items that can cause an engine to run lean (long term fuel trim is significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 Fuel Trim System Lean .
    • Check for proper operation of the Evaporative Emission (EVAP) control system. Refer to Evaporative Emission Control System Diagnosis .

Ignition System
    • Check for proper ignition voltage output with the J 36012-A spark plug jumper wires and J 26792 spark tester or equivalent.
    • Check the spark plugs for the following conditions:
       - Check for wet or fuel fouled spark plugs.
       - Check for cracks on the spark plugs.
       - Check for wear.
       - Check for improper spark plug gap.
       - Check for burned electrodes or heavy deposits.
    • If the spark plugs are fuel or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
    • Check the Ignition Control Module (ICM) for proper ground connection.
    • Check the ignition coils for cracks or carbon tracking.

Additional Checks
    • Check for proper operation of the Automatic Transaxle. Refer to Road Test in Automatic Transaxle.
    • Check the generator output voltage. Repair the generator if the output voltage is less than 11 volts or more than 16 volts.
    • If all procedures have been completed and no malfunctions have not been found, review and inspect the following items:
       - Visually and physically inspect all electrical connections within the suspected circuit and/or systems.
       - Check scan tool data.