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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1558 (Engine Controls And Fuel - 3.5L (L66) - Troubleshooting & Diagnosis) >> Cuts Out, Misses

Cuts Out, Misses

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
Cuts Out, Misses Symptom

Checks Action
DEFINITION: A steady pulsation or jerking that follows engine speed, usually more pronounced as the engine load increases. The exhaust has a steady spitting sound at idle, low speed or on hard acceleration.
Preliminary Checks
Sensor Checks Check the engine coolant temperature (ECT) sensor using a scan tool in order to compare the engine coolant temperature with the ambient air temperature on a cold engine. If the coolant temperature reading is more than 5°C (9°F) more or less than the ambient air temperature on a cold engine, check for a high resistance in the coolant sensor circuit or in the sensor. Refer to Temperature Versus Resistance - Engine Coolant Temperature Sensor .
Fuel System Checks
  • Perform the engine cylinder balance test:
    1. Start the engine.
    2. Use the scan tool in order to turn OFF each fuel injector one at a time. Refer to Scan Tool Output Controls .
    3. Observe the engine speed for each cylinder while testing.
    4. If there is an equal RPM drop on all cylinders, equal to within 50 RPM, the output from each cylinder is satisfactory.
  • Check for water contamination of the fuel.
Ignition System Checks Test the ignition system for the correct operation. Verify that each coil has good crisp, blue spark. Diagnose and repair any coil with a weak spark output. Refer to Electronic Ignition (EI) System Diagnosis .
Engine Mechanical Checks
  • Check for any of the following engine mechanical problems:
    • Any faulty hydraulic lifter assemblies
    • Any broken or weak valve springs
    • An incorrect valve timing
    • An incorrect or worn camshaft
  • Check the intake and exhaust manifold passages for casting flash.
  • Refer to the Symptoms - Engine Mechanical .
Additional Checks
  • An engine miss condition can be caused by electromagnetic interference (EMI) on the reference circuit. EMI can usually be detected by monitoring the engine speed with a scan tool. A sudden increase in speed with little change in the actual engine speed change indicates EMI is present.
  • Verify the powertrain control module (PCM) grounds are clean, tight, and in the correct locations. Refer to Engine Controls Schematics .