GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2000 🢒 Impala 🢒 Engine 🢒 Engine Controls - 3.4L 🢒 Cuts Out, Misses

Inspection/Test

Action

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

Preliminary
    •  Refer to Intermittent Conditions .
    •  Search for bulletins.

Fuel System
    •  Test the fuel pressure. Refer to Fuel System Pressure Test .
    •  Test the fuel injectors. Refer to the following procedures:
      •  Fuel Injector Balance Test
    • Test for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
    •  Inspect any items which may cause an engine to run rich. Refer to the Diagnostic Aids for DTC P0172.
    •  Inspect any items which may cause an engine to run lean. Refer to the Diagnostic Aids for DTC P0171.
    •  Inspect for fuel in the fuel pressure regulator vacuum hose.

Sensor/System
  1. Inspect for conditions which cause an incorrect idle speed:
    2. •  Any throttle body tampering, excessive deposits, or damage. Refer to Fuel Metering System Component Description .
    • A restricted air intake system
    •  Any large vacuum leak
    •  Inspect the air intake ducts for being collapsing, damaged areas, looseness, improper installation, or leaking, especially between the MAF sensor and the throttle body.
  2. Inspect the throttle position (TP) sensor and the related circuit wiring. Refer to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage .
  3. Monitor the 24X crankshaft position (CKP) and camshaft position (CMP) sensors on the scan tool. If neither sensor responds, test the sensor feed circuit. Both sensors use a separate feed circuit but are internally connected to power. Test all of the 24X sensor circuits and the CMP sensor circuits for intermittents. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  4. Monitor the 3X parameter on the scan tool. If the 3X is not responding, inspect the 7X CKP sensor and the circuits for intermittents. Inspect the IC circuit, the bypass circuit, the 3X reference high circuit, and the 3X reference low circuit for intermittents. If these circuits become open, or shorted may not set a DTC immediately, but are capable of causing driveability complaints. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  5. Test the exhaust gas recirculation (EGR) system for proper operation. Refer to Exhaust Gas Recirculation (EGR) System Description .
  6. Test the PCV valve for proper operation. Refer to Crankcase Ventilation System Description .
  7. Inspect the Transaxle Internal Mode Switch input with the vehicle in Drive and the gear selector in Drive or Overdrive.
  8. Inspect the following for damage:
    9. • Any bent harmonic balancer interrupter rings
    • A damaged crankshaft position sensor

Ignition System
    • Inspect for the proper ignition voltage output using the following procedure:
        1.  Attach the J 26792 spark tester to engine ground.
        2.  Connect the spark plug end of the spark plug wire to the J 26792 spark tester. Leave the other end of the spark plug wire connected to the coil being tested.
        3.  Connect the spark plug end of the companion spark plug wire to ground.

The companion spark plug wire is the wire attached to the corresponding coil tower.

        4.  Crank the engine while observing the J 26792 spark tester; 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:
       -  Check the coils for cracks, carbon tracking and arcing, or a resistance value outside the specified range.

Coil Resistance
5,000-8,000 ohms

       -  Check the spark plug wires for signs of arcing, cross firing, cracks, carbon tracking, plug boot damage, pinching, improper routing, or a resistance value outside the specified range.

Spark Plug Wire Resistance
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 problem. The ignition voltage will arc to ground when a secondary component is faulty.

       -  Check for a defective ignition module.
       -  Check the ignition system wiring for a loose ignition module feed or ground connection, or damaged system wiring.
    •  Remove spark plugs and inspect for the following conditions:
       -  Fouling
       -  Cracks
       -  Wear
       -  Improper gap
       -  Burned or damaged electrodes
       -  Improper heat range or reach
    •  If the spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs. Refer to Spark Plug Visual Diagnosis in Engine Electrical.

Engine Mechanical
    •  Inspect for the following engine mechanical conditions:
       -  Test the compression--Refer to Engine Compression Test in Engine Mechanical.
       -  Sticking or leaking valves
       -  Worn camshaft lobes
       -  Valve timing
       -  Bent push rods
       -  Worn rocker arms
       -  Broken valve springs
       -  Excessive oil in the combustion chambers and leaking valve seals
       -  Low cylinder compression
    •  Inspect the following components for incorrect basic engine parts:
       -  The camshaft
       -  The cylinder heads
       -  The pistons, etc.
    •  Refer to Base Engine Misfire Diagnosis in Engine Mechanical.

Additional
    • Inspect the exhaust system for restrictions:
       -  Inspect the exhaust system for damaged or collapsed pipes.
       -  Inspect the mufflers for heat distress or internal failure.
       - Inspect for a plugged 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 the 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 the routing of the secondary ignition wires and the high voltage components near the ignition control circuits.
    •  Inspect for intake and exhaust manifold passages for casting flash.
    •  Inspect for faulty motor mounts.