## Fuel and Emissions Systems

#### Symptom Troubleshooting Index (cont'd)

11-10

Symptom | Diagnostic Procedure | Also check for
When cold idle out of spec. |

1. Intake System.

   (Intake manifold, air cleaner, MAF sensor)

2. Glow System.

   (Glow Relay, Glow Plug)

3. Injection Timing System.

   (CKP Sensor, CMP Sensor, Mechanical timing)

4. Fuel filter, Fuel Line, Fuel, Fuel Condition.
5. Fuel Injection System.

   (Injector, Supply Pump, Common Rail)

6. ECM (ECT Sensor, ECM, Fail Safe Mode)

Rough idle |

1. Intake System.

   (Intake manifold, air cleaner)

2. Fuel filter, Fuel Line, Fuel, Fuel Condition.
3. Throttle System.

   (AP Sensor, Throttle cable)

4. Injection Timing System.

   (CKP Sensor, CMP Sensor, Mechanical timing)

5. Exhaust System.

   (EGR system, Turbocharger, Vacuum system)

6. Fuel Injection System.

   (Injector, Supply Pump, Common Rail)

- Low Compression
- Contaminated Fuel
- Chassis Parts Error

When warm engine speed too high |

1. Throttle System.

   (AP Sensor, Throttle cable)

2. Fuel Injection System.

   (Injector, Common Rail)

3. ECM (ECT Sensor, ECM, Fail Safe Mode)

When warm engine speed too low |

1. Oil viscosity.
2. Intake System.

   (Intake manifold, air cleaner, MAF sensor)

3. Throttle System.

   (AP Sensor, Throttle cable)

4. Fuel Injection System.

   (Injector, Supply Pump, Common Rail)

Over Heat |

1. Thermostat, Radiator, Cooling Fan, Coolant
2. Fuel Injection System.

   (Injector, Common Rail, ECM)

Over Run |

1. Operation Error
2. Fuel Injection System.

   (Injector, Common Rail, ECM)

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