GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2003 🢒 Bonneville 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Cuts Out, Misses

Checks

Action

DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases.

Preliminary
    • Refer to Important Preliminary Checks Before Starting.
    • Refer to Visual/Physical Checks.
    • Search for bulletins.

Fuel System
    • Test system fuel pressure. Refer to Fuel System Diagnosis .
    • Test the fuel injectors using the following tests:
       - Refer to Fuel Injector Solenoid Coil Test .
       - Refer to Fuel Injector Balance Test with Tech 2 .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect items which can cause an engine to run rich (long term fuel trim significantly in the negative range). Refer to Diagnostic Aids for DTC P0172 .
    • Inspect items that can cause an engine to run lean (long term fuel trim significantly in the positive range). Refer to Diagnostic Aids for DTC P0171 .
    • Inspect for fuel in the fuel pressure regulator vacuum hose.

Sensor/System
    • Inspect for conditions which cause an incorrect idle speed.
       - Throttle body tampering, excessive deposits, or damage
       - Restricted air intake system--Refer to Air Intake System Description .
       - Large vacuum leak
    • Test the throttle position (TP) sensor and related circuit wiring. Refer to DTC P0123 .
    • Test the exhaust gas recirculation (EGR) system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .
    • Test the positive crankcase ventilation (PCV) valve for proper operation.
    • Test the transaxle range switch input with the vehicle in drive and the gear selector in drive or overdrive.
    • Inspect the following for damage:
       - Bent harmonic balancer interrupter rings. Refer to Crankshaft Balancer Replacement in Engine Mechanical-3.8L.
       - Damaged crankshaft position sensor. Refer to Crankshaft Position Sensor Replacement .

Ignition System
    • Test for proper ignition voltage output using the following steps:
        1. Clip the J 26792 spark tester to engine ground.
        2. Connect one end of a spark plug wire to the J 26792 . Connect the other end of the spark plug wire to the coil being tested.
        3. Connect another spark plug wire between the remaining tower of the coil being tested and ground.
        4. Crank the engine while observing the J 26792 . A spark should be observed.
        5. Repeat the above steps for each coil.
    • If spark is not present at the coils, inspect for the following conditions:
       - Coils--Cracks, carbon tracking/arcing, or a secondary resistance value outside the specified range

Coil Resistance
5000-8000 ohms (5K-8K ohms)

       - Spark plug wires--Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range

Spark Plug Wire Resistance
9840 ohms per meter (3000 ohms per foot)

Spark Plug Wire Resistance Police
1,968 ohms per meter (600 ohms per foot)

   Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent condition. Ignition components will arc to ground when a secondary component is faulty.

       - Defective module
       - Ignition system wiring--Loose ignition module feed or ground connection, or damaged system wiring
    • Remove spark plugs and inspect for the following:
       - Fouled plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned or damaged electrodes
       - Improper heat range or reach
    • If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs. Refer to Spark Plug Inspection .
    • Test for the following intermittent ignition system conditions:
       - Intermittent CKP 18X signal
       - Intermittent ignition feed circuit or sensor ground circuit to the crankshaft position sensor or the camshaft position sensor
       - Intermittent 3X reference signal
       - Intermittent camshaft position signal

Engine Mechanical
    • Test and inspect engine mechanical for the following:
       - Test compression, refer to Engine Compression Test in Engine Mechanical-3.8L.
       - Sticking or leaking valves
       - Worn camshaft lobes
       - Valve timing
       - Bent push rods, refer to Valve Rocker Arm and Push Rod Cleaning and Inspection in Engine Mechanical-3.8L.
       - Worn rocker arms, refer to Valve Rocker Arm and Push Rod Cleaning and Inspection in Engine Mechanical-3.8L.
       - Broken valve springs, refer to Cylinder Head Cleaning and Inspection in Engine Mechanical-3.8L.
       - Excess oil in combustion chamber--Inspect for leaking valve seals.
    •  Inspect for incorrect basic engine parts, such as the following basic components:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.

Refer to Symptoms - Engine Mechanical in Engine Mechanical-3.8L.

Additional Checks
    • Test exhaust system for possible restrictions. Inspect for the following:
       - Inspect exhaust system for damaged or collapsed pipes.
       - Inspect mufflers for heat distress or possible internal failure.
       - For possible plugged 3-way catalytic converter--Refer to Restricted Exhaust in Engine Exhaust.
    •  An engine miss condition can be caused by electromagnetic interference (EMI) on the reference circuit. EMI can usually be detected by monitoring engine RPM with a scan tool. A sudden increase in RPM with little change in actual engine RPM change, indicates EMI is present. If a condition exists, inspect routing of secondary ignition wires, high voltage components (near ignition control circuits).
    • Inspect for intake and exhaust manifold passages for casting flash.
    • Inspect for faulty motor mounts.