GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2000 🢒 Regal 🢒 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 in Symptoms before Starting.
    • Refer to Visual/Physical Checks in Symptoms .
    • Search for bulletins.

Fuel System
    • Test system fuel pressure. Refer to Fuel System Pressure Test (VIN K) or Fuel System Pressure Test (VIN 1) .
    • Test the fuel injectors using the following tests:
       - Refer to Fuel Injector Balance Test .
    • 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 Fuel Trim System Rich .
    • 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 Fuel Trim System Lean .
    • Inspect for fuel in the fuel pressure regulator vacuum hose.

Sensor/System
  1. Inspect for conditions which cause an incorrect idle speed:
    2.  - Throttle body tampering, excessive deposits, or damage. Refer to Fuel Metering Modes of Operation .
     - Restricted air intake system. Refer to Air Intake System Description .
     - Large vacuum leak.
  2. Test the TP sensor and 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 valve for proper operation. Refer to Crankcase Ventilation System Description .
  5. Test the transaxle range switch input with the vehicle in drive and the gear selector in drive or overdrive.
  6. Inspect the following for damage:
    7.  - Bent harmonic balancer interrupter rings
     - Crankshaft position sensor

Ignition System
    • Check for proper ignition voltage output using the following steps:
       - Clip the J 26792 spark tester to engine ground.
       - Connect one end of a spark plug wire to the spark tester. Leave the other end of the spark plug wire to the coil being tested.
       - Connect one end of another spark plug wire to the other coil tower. Connect the other end of the spark plug wire to ground.
       - Crank the engine while observing the spark tester. A spark should be observed.
       - 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
600 ohms per ft

   Important: Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. 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.
    • 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
       - Sticking or leaking valves
       - Worn camshaft lobes
       - Valve timing
       - Bent push rods
       - Worn rocker arms
       - Broken valve springs
       - Excessive oil in combustion chamber -- Leaking valve seals
       - Low cylinder compression
    • For incorrect basic engine parts -- Inspect the following:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.

Additional Checks
    • Test exhaust system for possible restrictions. Inspect for the following:
       -  Exhaust system for damaged or collapsed pipes.
       -  Mufflers for heat distress or possible internal failure.
       - For possible plugged three-way catalytic converter. Refer to Restricted Exhaust System Check .
    •  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 problem exists, inspect routing of secondary ignition wires, high voltage components, near the Ignition Control circuits).
    • Inspect for intake and exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection in Engine Mechanical.
    • Inspect for faulty motor mounts.