GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Isuzu 🢒 2001 🢒 S/T Isuzu - 4WD 🢒 Engine 🢒 Engine Electrical 🢒 Cuts Out, Misses

Checks

Action

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

Preliminary
    •  Refer to Symptoms - Engine Controls .
    •  Search for service bulletins.
    • Connect a scan tool and look at the misfire data to possibly isolate a specific cylinder fault.

Fuel System
    • Check system fuel pressure. Refer to Fuel System Diagnosis .
    • Check the fuel filter for a plugged or restricted condition.
    • Check items which can cause an engine to run rich--Long Term FT significantly in the negative range. Refer to Diagnostic Aids for DTC P0172 .
    • Check items that can cause an engine to run lean--Long Term FT significantly in the positive range. Refer to Diagnostic Aids for DTC P0171 .
    • Check for proper operation of the evaporative emission (EVAP) control system.

Sensor/System
    • Check the oxygen sensor (O2S 1). The O2S 1 should respond quickly to different throttle positions. If not, check the O2S 1 for silicon or other contaminants from fuel or the use of improper RTV sealant. The sensors may have a white powdery coating. Silicon contamination causes a high but false O2S 1 signal voltage--rich exhaust indication. The powertrain control module (PCM) will reduce the amount of fuel delivered to the engine, causing a severe driveability problem.
    • Check for proper operation of the MAP sensor..
    • Check for proper operation of the TP sensor.
    • Check for proper operation of the ECT sensor.
    • Check for proper operation of the CKP sensor.
    • Check for proper operation of the CMP sensor.

Ignition System
    • Check for proper ignition voltage output with the J 26792 spark tester.
    • Check the spark plugs for the following conditions:
       - Wet or fuel fouled spark plugs
       - Cracks on the spark plugs
       - Wear
       - Improper spark plug gap
       - Burned electrodes or heavy deposits
    • If the spark plugs are fuel or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.
    • Check the ignition control module (ICM) for proper ground connection.
    • Check the ignition coils for cracks or carbon tracking.
    • Check the spark plug wires for proper resistance and condition.

Engine Mechanical
    • Check engine mechanical for the following:
       - 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 combustion chamber and leaking valve seals
       - Low cylinder compression
    •  Inspect the following components for incorrect basic engine parts:
       - Camshaft
       - Cylinder heads
       - Pistons, etc.
    • Refer to the appropriate diagnostic procedures in Engine Mechanical.

Additional Checks
    • Check the following components of the exhaust system for possible restrictions:
       - 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 malfunctioning motor mounts.