GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2003 🢒 Express 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Cuts Out, Misses

Checks

Action

DEFINITION: A jerking that follows engine speed, usually more pronounced as the engine load increases which is not normally felt above 1,500 RPM or 48 km/h (30 mph).

Preliminary Check

Refer to Symptoms - Engine Controls .

Ignition System Checks

Check for a cylinder misfire:

  1. Start the engine.
  2. Allow the engine to stabilize.
  3. Disconnect the idle air control (IAC) motor.

    4. Notice: Do not perform this test for more than 2 minutes in order to prevent damaging the catalytic converter.

  4. Perform the Cylinder Power Balance Test with a scan tool.
  5. If there is a RPM drop on all cylinders, equal to within 50 RPM, refer to Rough, Unstable, or Incorrect Idle and Stalling .
  6. Reconnect the IAC motor with the ignition OFF.
  7. If there is no RPM drop on one or more of the cylinders, or excessive variation in drop, check for spark on the suspected cylinders with a J 26792 Spark Tester or equivalent.
  8. If there is no spark, refer to Distributor Ignition (DI) System Diagnosis .
  9. If there is spark, remove the spark plugs in these cylinders and check for the following conditions:
    10. • Insulation cracks
    • Wear
    • Improper gap
    • Burned electrodes
    • Heavy deposits
    • Refer to Spark Plug Inspection .
       - Check the spark plug wire resistance. The resistance should not exceed 1,000 ohms per foot.
       - Check the distributor rotor and the distributor cap.
       - If the previous check did not find the problem, visually check the following items:
    • The ignition system for moisture, dust, cracks, burns, etc.
    • With the engine running, spray the plug wires with a fine water mist to check for shorts.
    • Perform the Fuel Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 .

Engine Mechanical Checks
    • Perform a cylinder compression check. Refer to Engine Compression Test in Engine Mechanical.
    • Check the engine for the following:
       - Improper valve timing
       - Bent pushrods--Refer to Valve Rocker Arm and Push Rod Cleaning and Inspection in Engine Mechanical.
       - Worn rocker arms--Refer to Camshaft and Bearings Cleaning and Inspection in Engine Mechanical.
       - Worn camshaft lobes--Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical.
       - Broken or weak valve springs--Refer to Upper Engine Noise, Regardless of Engine Speed in Engine Mechanical.
    • Check the intake and exhaust manifold passages for casting flash.

Fuel System Checks
    • Check the fuel pressure. Refer to Fuel System Diagnosis .
    • Check for water contamination in the fuel.
    • Perform the fuel injector coil test. Refer to Fuel Injector Solenoid Coil Test .
    • Perform the fuel injector balance test. Refer to Fuel Injector Balance Test with Tech 2 .

Additional Check
    • Check for electromagnetic interference (EMI).
    • Check the routing of the secondary wires and the ground circuit.