For 1990-2009 cars

#### Cuts Out, Misses

Tests/Inspections | Action
--- | ---
DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases.
Preliminary |

• | Refer to Powertrain On Board Diagnostic (OBD) System Check .

• | Refer to Symptoms .

• | Search for service bulletins.

Fuel System |

• | Test the fuel pressure. Refer to Fuel System Diagnosis .

• | Test the fuel injectors. Refer to Fuel Injector Balance Test .

• | Test for a contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

• | Inspect for a restricted fuel filter.

• | Inspect the 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 the 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 .

• | Test for the correct operation of the evaporative emission (EVAP) control system. Refer to Evaporative Emission Control System Diagnosis .

• | Inspect for fuel in the fuel pressure regulator vacuum hose.

Sensor/System |

• | Test the oxygen sensor (O2S 1). The O2S 1 should respond quickly to different throttle positions. If not, inspect the O2S 1 for silicon or other contaminants from fuel or the use of improper RTV sealant. The sensor may have a white powdery coating. Silicon contamination causes a high but false O2S 1 signal voltage (rich exhaust indication). The PCM will reduce the amount of fuel delivered to the engine, causing a severe driveability problem. Refer to Information Sensors/Switches Description .

• | Test for correct operation of the manifold absolute pressure (MAP) sensor. Refer to Manifold Absolute Pressure Sensor Output Diagnosis .

• | Test for the correct operation of the throttle position (TP) sensor.

• | Test for the correct operation of the engine coolant temperature (ECT) sensor.

Ignition System |

• | Test for the correct ignition voltage output.

• | Inspect the spark plugs for the following conditions:

- | Any wet or fuel fouled plugs

- | Any racks

- | An incorrect gap

- | Any burnt 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.

• | Inspect the ignition control module (ICM) for a correct ground connection.

• | Inspect the ignition coils and the housing for cracks or carbon tracking.

Engine Mechanical |

• | Inspect for the following conditions:

- | Any sticking or leaking valves

- | Any worn camshaft lobes

- | An incorrect valve timing

- | Any broken valve springs

- | Refer to Valve Train Diagnosis in Engine Mechanical.

- | Any excessive oil in a combustion chamber and leaking valve seals

- | The correct oil viscosity

- | A low compression

- | Refer to Engine Compression Test in Engine Mechanical.

• | Any incorrect basic engine parts. Inspect the following:

- | The camshafts

- | The cylinder head

- | The pistons, etc.

• | Refer to Engine Mechanical Specifications in Engine Mechanical.

Additional |

• | Inspect the exhaust system for the following conditions:

- | Any damaged or collapsed pipes

- | Any heat distress or internal failure of the muffler

- | A plugged 3-way catalytic converter. Refer to Restricted Exhaust .

• | 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 the actual engine RPM change indicates EMI is present. If a problem exists, inspect the routing of secondary ignition wires near high voltage components.

• | Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection and to Exhaust Manifold Cleaning and Inspection in Engine Mechanical .

• | Inspect for malfunctioning engine mounts. Refer to Engine Mount Inspection in Engine Mechanical .

• | An intermittent may be caused by the following conditions:

- | Any faulty connections.

- | A rubbed through wire insulation.

- | BA broken wire inside the insulation.

• | Inspect the circuitry that is suspected of causing an intermittent complaint for the following conditions:

- | Any backed out terminals.

- | Any incorrect mating of terminals.

- | Any incorrectly formed or damaged terminals.

- | Any faulty terminal-to-wiring connections.

- | Any physical damage to the wiring harness.

- | Any corrosion.