GM Service Manual Online
For 1990-2009 cars only

Cuts Out, Misses

Checks

Action

DEFINITION: A steady pulsation or jerking that increases with the engine speed. The condition is usually more pronounced when the engine load increases.

Preliminary

    •  Refer to Symptoms - Engine Controls .
    •  Search the service bulletins.

Fuel System

Check for the following conditions:

    • The system fuel pressure--Refer to Fuel System Diagnosis .
    • The fuel injectors--Refer to Fuel Injector Balance Test with Tech 2 .
    • Contaminated fuel--Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing.
    • Check for a restricted fuel filter.
    • Conditions which can cause an engine to run rich, indicating that the long-term fuel trim is significantly in the negative range--Refer to Diagnostic Aids for DTC P0172 .
    • Conditions which can cause an engine to run lean, indicating that the long-term fuel trim is significantly in the positive range--Refer to Diagnostic Aids for DTC P0171 .
    • Proper operation of the evaporative emission (EVAP) control system
    • Check for fuel in the fuel pressure regulator vacuum hose.

Sensor/System

Check for the following conditions:

    • The oxygen sensor (O2S 1)--The O2S 1 should quickly respond to the different throttle positions. If it does not respond, check the O2S 1 for silicon, or for other contaminants from the fuel, or from the use of an improper RTV sealant. The sensor may have a white powdery coating. Silicon contamination causes a high but false O2S 1 signal voltage, indicating a rich exhaust indication. The PCM will reduce the amount of fuel that is delivered to the engine, causing a severe driveability problem.
    • Proper operation of the following components:
       - The manifold absolute pressure (MAP) sensor
       - The throttle position (TP) sensor
       - The engine coolant temperature (ECT) sensor

Ignition System

Check for the following conditions:

    • Proper ignition voltage output--Use the J 36012-A Spark Plug Jumper Wires and the J 26792 Spark Tester, or equivalent.
    • Check the spark plugs for the following conditions:
       - Wet spark plugs
       - Fuel-fouled spark plugs
       - Cracked spark plugs
       - Wear
       - Improper spark plug gap
       - Burned electrodes
       - Heavy deposits
    • If the spark plugs are fuel or oil-fouled, determine the cause of the fouling before you replace the spark plugs.
    • The ignition control module (ICM) for proper ground connection
    • The ignition coils for cracks or carbon tracking
    • The internal and external ignition coil housing for cracks and for carbon tracking

Engine Mechanical

Check for the following conditions:

    • Sticking valves
    • Leaking valves
    • Worn camshaft lobes
    • The valve timing
    • Broken valve springs
    • Excessive oil in the combustion chamber, caused by leaking valve seals
    • Proper oil viscosity
    • Low cylinder compression
    • Incorrect basic engine parts--Inspect the following components:
       - The camshafts
       - The cylinder head
       - The pistons
       - Other components, as necessary

Additional Checks

    • Check the exhaust system for possible restrictions. Check for the following conditions:
       - Inspect the exhaust system for damaged pipes, or for collapsed pipes.
       - Inspect the mufflers for heat distress, or for possible internal failure.
       - Inspect for a plugged 3-way catalytic converter. Refer to Restricted Exhaust in Engine Exhaust.
    • Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. You can usually detect EMI by monitoring the engine RPM with a scan tool. A sudden increase in the RPM, with little change in the actual engine RPM change indicates that EMI is present. If a problem exists, check the routing for the following components:
       - The secondary ignition wires
       - The high-voltage components, near the ignition control circuits
    • Check the intake and exhaust manifold passages for casting flash. Refer to Symptoms - Engine Mechanical in Engine Mechanical 2.4L.
    • Check for malfunctioning engine mounts. Refer to Symptoms - Engine Mechanical in Engine Mechanical 2.4L.
    • The following conditions can cause an intermittent connection:
       - Poor electrical connections
       - Rubbed through wire insulation
       - Broken wire inside the insulation
    • Thoroughly check any circuitry that you suspect of causing an intermittent complaint for the following conditions:
       - Backed-out terminals
       - Improper terminal mating
       - Improperly-formed terminals
       - Damaged terminals
       - Poor terminal-to-wire electrical connections
       - A damaged wiring harness
       - Corrosion