For 1990-2009 cars

#### Cuts Out, Misses

Checks | 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 |

• | Check system fuel pressure. Refer to Fuel System Diagnosis .

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

• | Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis Testing.

• | Check the fuel filter for being plugged or restricted.

• | 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 proper operation of the Evaporative Emission (EVAP) control system. Refer to Evaporative Emission Control System Diagnosis .

• | Check for fuel in the Fuel Pressure Regulator vacuum hose.

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 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 Oxygen sensor in Information Sensors/Switches Description .

• | Check for proper operation of the MAP Sensor. Refer to Manifold Absolute Pressure Sensor Output Diagnosis .

• | Check for proper operation of the TP sensor.

• | Check for proper operation of the ECT sensor.

Ignition System |

• | Check for proper ignition voltage output with the J 36012-A spark plug jumper wires and J 26792 spark tester or equivalent.

• | Check the spark plugs for the following conditions:

- | Check for wet or fuel fouled spark plugs.

- | Check for cracks on the spark plugs.

- | Check for wear.

- | Check for improper spark plug gap.

- | Check for 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 ignition coil housing internal or external for cracks or carbon tracking.

Engine Mechanical |

• | Check the following:

- | Sticking or leaking valves.

- | Worn camshaft lobe(s).

- | Valve timing.

- | Broken valve springs.

- | Excessive oil in combustion chamber-Leaking valve seals.

- | Proper oil viscosity.

- | Low cylinder compression.

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

- | Camshafts

- | Cylinder head

- | Pistons, etc.

• | Refer to Engine Mechanical.

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. Refer to Engine Mechanical .

• | Check for malfunctioning engine mounts. Refer to Engine Mechanical .

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

- | Poor electrical connections.

- | Rubbed through wire insulation.

- | Wire broken inside the insulation.

• | Any circuitry that is suspected as causing an intermittent complaint should be thoroughly checked for the following conditions:

- | Backed out terminals.

- | Improper mating of terminals.

- | Improperly formed or damaged terminals.

- | Poor terminals to wiring electrical connections.

- | Physical damaged to the wiring harness.

- | Corrosion.