GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2003 🢒 Jimmy - 4WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Surges/Chuggles

Checks

Action

DEFINITION: The engine has a power variation under a steady throttle or cruise. The vehicle feels as if it speeds up and slows down with no change in the accelerator pedal position.

Preliminary Checks
    • Refer to Symptoms - Engine Controls .
    • Be sure the driver understands the torque converter clutch operation.
    • Be sure the driver understands the A/C compressor operation.
    • Ensure that the transmission fluid is at the proper level.

Sensor Check

Display the scan tool parameters for the various engine controls sensors. Check for any abnormal readings.

Fuel System Checks
    • Check for a rich or lean symptom that causes the condition. Drive the vehicle at the speed of the complaint. Monitoring the fuel trim will help identify the problem.
    • Lean--The long term fuel trim will be more than 23 percent. Refer to DTC P0171 or P0174 .
    • Rich--The long term fuel trim will be less than 13 percent. Refer to DTC P0172 or P0175 .
    • Check the fuel pressure while the condition exists. Refer to Fuel System Diagnosis .
    • Check the in-line fuel filter for a restrictions.

Ignition System Checks
    • Check for the proper ignition output voltage using the J 26792 Spark Tester or the equivalent. Refer to Distributor Ignition (DI) System Diagnosis .
    • Check the secondary ignition system and spark plugs. Remove the plugs and inspect them for the following conditions:
       - Wetness
       - Cracks
       - Wear
       - Improper gap
       - Burned electrodes
       - Heavy deposits
       - Refer to Spark Plug Inspection .
    • Check for a loose or damaged crankshaft position (CKP) sensor and reluctor wheel. Refer to Crankshaft Position Sensor Reluctor Ring Replacement in Engine Mechanical or Crankshaft Position Sensor Replacement .

Additional Checks
    • Check the control module grounds for being clean, tight, and in their proper locations.
    • Check the generator output voltage.
    • Check the vacuum hoses for kinks or leaks. Refer to the Vehicle Emission Control Information label.
    • Check for torque converter clutch (TCC) operation. Refer to Diagnostic Starting Point - Automatic Transmission in Automatic Transmission.
    • Check the exhaust system for a possible restriction. Refer to Restricted Exhaust in Engine Exhaust.