GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Grand Prix 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 Cuts Out, Misses

Checks

Action

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

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

Fuel System
    • Test the fuel system pressure. Refer to Fuel System Pressure Test (VIN K) . Refer to Fuel System Pressure Test (VIN 1) .
    • Test the fuel injectors using the following tests:
       -  Fuel Injector Balance Test .
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Inspect for conditions which can cause an engine to run rich, indicating a long-term fuel trim that is significantly in the negative range. Refer to DTC P0172 Fuel Trim System Rich .
    • Inspect for conditions that can cause an engine to run lean, indicating that the long-term fuel trim is significantly in the positive range. Refer to DTC P0171 Fuel Trim System Lean .
    • Inspect for fuel in the fuel pressure regulator vacuum hose.

Sensor/System
  1. Inspect for conditions which can cause an incorrect idle speed.
    2.  - Inspect for throttle body tampering, for excessive deposits, or for damage. Refer to Fuel Metering System Component Description .
     - Inspect for a restricted air intake system. Refer to Air Intake System Description .
     - Inspect for a large vacuum leak.
  2. Test the TP Sensor and test the related circuit wiring. Refer to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage .
  3. Test the EGR system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .
  4. Test the PCV for proper operation. Refer to Crankcase Ventilation System Description .
  5. Test the transaxle range switch input with the vehicle in drive, and with the gear selector in drive or overdrive.
  6. Inspect for the following components:
    7.  - Bent harmonic balancer interrupter rings for bends
     - A damaged crankshaft position sensor

Ignition System
    • Check for proper ignition voltage output using the following steps:
        1. Clip the spark tester J 26792 to engine ground.
        2. Connect one end of a spark plug wire to the spark tester, and leave the other end of the spark plug wire to the coil that is being tested.
        3. Connect one end of another spark plug wire to the other coil tower, and connect the other end of the spark plug wire to ground.
        4. Crank the engine while you observe the spark tester. You should observe a spark.
        5. Repeat the above steps for each coil.
    • If there is no spark at the coils, inspect for the following conditions:
       - The coils--Inspect for cracks, for carbon tracking or arcing, or for a secondary resistance value that is outside the specified range.

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

       - The spark plug wires--Inspect for signs of arcing or cross-firing, for cracks, for carbon tracking, for plug boot damage, for pinches, for improper routing, or a resistance value that is outside the specified range.

Spark Plug Wire Resistance
600 ohms per ft.

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

       - A defective module
       - The ignition System Wiring--Inspect for a loose ignition module feed or ground connection, or for damaged system wiring.
    • Remove the spark plugs and inspect for the following conditions:
       - Fouled plugs
       - Cracks
       - Wear
       - Improper gap
       - Burned or damaged electrodes
       - Improper heat range or reach
    • If the spark plugs are gas or oil fouled, determine the cause of the fouling before you replace the spark plugs.
    • Test for the following intermittent ignition system conditions:
       - An intermittent CKP 18X signal.
       - An intermittent ignition feed circuit or sensor ground circuit to the crankshaft position sensor or to the camshaft position sensor
       - An intermittent 3X reference signal
       - An intermittent camshaft position signal

Engine Mechanical
    • Test and inspect the engine mechanical components for the following conditions:
       - Test compression
       - Sticking or leaking valves
       - Worn camshaft lobes
       - Valve timing
       - Bent push rods
       - Worn rocker arms
       - Broken valve springs
       - Excessive oil in the combustion chamber that is caused by leaking valve seals.
       - Low cylinder compression
    • Inspect for incorrect basic engine parts. Inspect the following conditions:
       - the camshaft
       - The cylinder heads
       - The pistons
       - Other components, as applicable

Additional Checks
    • Test the exhaust system for possible restrictions. Inspect for the following conditions:
       - Damaged or collapsed pipes in the exhaust system.
       - Heat distress or possible internal failure in the muffler
       - A plugged 3-way catalytic converter--Refer to Restricted Exhaust System Check in Engine Exhaust.
    •  An engine miss condition can be caused by electromagnetic interference (EMI) on the reference circuit. You can usually detect EMI by monitoring the engine RPM with a scan tool. A sudden increase in RPM, with little change in the actual engine RPM indicates that EMI is present. If a problem exists, inspect the routing for the secondary ignition wires, and for high voltage components that are near the ignition control circuits.
    • Inspect the intake and exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection refer to in Engine Mechanical.
    • Inspect for faulty motor mounts.