For 1990-2009 cars

#### Cuts Out, Misses

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

• | Refer to Diagnostic System Check - Engine Controls .

• | Refer to Symptoms - Engine Controls .

• | 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 with Special Tool or Fuel Injector Balance Test with Tech 2 .

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

• | Check 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 .

• | 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 .

• | 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.

• | Test for correct operation of the manifold absolute pressure (MAP) sensor.

• | 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 with the J 36012-A spark plug jumper wires and J 26792 spark tester or equivalent.

• | 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

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

- | The correct oil viscosity

- | Refer to Symptoms - Engine Mechanical in Engine Mechanical.

• | Check for 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 Symptoms - Engine Mechanical 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 in Engine 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 Symptoms - Engine Mechanical 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.

- | A 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.