GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2000 🢒 Catera 🢒 Engine 🢒 Engine Controls - 3.0L (L81) 🢒 Hesitation, Sag, Stumble

Checks

Action

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

Preliminary
    • Refer to Important Preliminary Inspections Before Starting in Symptoms .
    • Search for bulletins.
    • Inspect the ECM grounds for being clean, tight, and in the proper locations. Refer to Engine Controls Schematics .

Sensor/System
    • Test the heated oxygen sensors (HO2S). The HO2S should respond quickly to the different throttle positions. If they do not, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white powdery coating. This type of contamination may result in a rich exhaust indication. The ECM will then reduce the amount of fuel delivered to the engine, causing a severe driveability condition.
    • Inspect the mass air flow (MAF) sensor connections. Repair or replace the terminals as necessary. Refer to Connector Repairs in Wiring Systems.
    • Inspect the CMP sensor for proper operation or intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Inspect the CKP sensor for proper operation or intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • Check for the proper operation of the throttle control system components. Use the special functions to actuate the system. With a scan tool monitor the following throttle control components:
       - Throttle position sensors
       - Accelerator pedal position sensors
       - Throttle actuator

Fuel System
    • Test for proper 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 .
    • Test the fuel injectors. Refer to 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 Fuel Trim System Rich Bank 1 and DTC P0175 Fuel Trim System Rich Bank 2 .
    • 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 Fuel Trim System Lean Bank 1 and DTC P0174 Fuel Trim System Lean Bank 2 .

Ignition System
    • Test for proper ignition voltage output with a J 26792 spark tester. Refer to Ignition System Check .
    • Test for secondary ignition system leakage. Perform the procedure in the Diagnostic Aids portion of Ignition System Check .
    • Remove the spark plugs and inspect for the following conditions:
       - Correct heat range
       - Wet plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
    • An improper spark plug gap may cause a driveability concern. Gap the spark plugs using a wire gauge gap tool. Refer to Spark Plug Replacement in Engine Electrical.
    • 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 Visual Diagnosis in Engine Electrical.
       - For diagnosis of a rich condition, refer to DTC P0172 Fuel Trim System Rich Bank 1 or DTC P0175 Fuel Trim System Rich Bank 2 .
       - 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 Cooling System

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

Additional Checks

Test the generator output voltage. Refer to Diagnostic System Check - Engine Electrical in Engine Electrical. Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.