GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 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 Before Starting.
    • Refer to Visual/Physical Checks.
    • Search for bulletins.

Fuel System
    • Check system fuel pressure. Refer to Fuel System Pressure Test (VIN K) or Fuel System Pressure Test (VIN 1) .
    • Check the fuel injectors. Refer to the following procedures:
       -  Fuel Injector Balance Test
    • Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    • Check 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 .
    • Check 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 .
    • Check for fuel in the Fuel Pressure Regulator vacuum hose.

Sensor/System
    • Check for conditions which cause an incorrect idle speed.
       - Throttle body tampering, excessive desposits, or damage. Refer to Fuel Metering System Component Description .
       - Restricted air intake system. Refer to Air Intake System Description .
       - Large vacuum leak.
    • Check the TP Sensor and related circuit wiring. Refer to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage .
    • Check the EGR system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .
    • Check the PCV Valve for proper operation. Refer to Air Intake System Description .
    • Check the Transaxle Range Switch input with the vehicle in drive and the gear selector in drive or overdrive.
    • Check the following for damage:
       - Bent harmonic balancer interrupter rings.
       - Damaged Crankshaft Position Sensor.

Ignition System
    • Check for proper ignition voltage output using the following steps:
       - Clip the spark tester J 26792 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 coil(s), check for the following conditions:
       - Coil(s) - 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 check 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.
    • Check 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
    • Check engine mechanical for the following:
       - Check compression.
       - Sticking or leaking valves.
       - Worn camshaft lobe(s).
       - 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.
    • Refer to Base Engine Misfire Diagnosis .

Additional Checks
    • Check exhaust system for possible restrictions. Check for the following:
       - Inspect exhaust system for damaged or collapsed pipes.
       - Inspect 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, check routing of secondary ignition wires, high voltage components (Near Ignition Control circuits).
    • Check for intake and exhaust manifold passages for casting flash. .
    • Check for faulty motor mounts. Refer to Engine Mechanical