GM Service Manual Online
For 1990-2009 cars only

Checks

Action

DEFINITION: A constant jerking that follows the engine speed, usually more pronounced as the engine load increases which is not normally felt above 1500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle, low speed, or hard acceleration for the fuel starvation that can cause the engine to cut-out.

Preliminary Check

Refer to Symptoms .

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
       - Worn rocker arms
       - Worn camshaft lobes
       - Broken or weak valve springs, refer to Valve Train Diagnosis in Engine Mechanical.
    • Check the intake and exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection in Engine Mechanical.

Fuel System Checks

    • Check the fuel system for a plugged fuel filter, low fuel pressure, air in the fuel system, etc. Refer to Fuel Supply System Check .
    • Check for water contamination in the fuel. Refer to Contamination Testing .