Fuel Injection System: Notes
DESCRIPTION
The fuel injection system consists of the following:
| 1. | Refer to MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR . |
| 2. | Refer to FUEL INJECTORS . |
| 3. | Refer to POWERTRAIN CONTROL MODULE (PCM) . |
| 4. | Refer to THROTTLE BODY . |
| 5. | Refer to CAMSHAFT POSITION (CMP) SENSOR . |
| 6. | Refer to IGNITION COIL . |
| 7. | Refer to CRANKSHAFT POSITION (CKP) SENSOR . |
| 8. | Refer to OXYGEN (O2) SENSOR . |
| 9. | Refer to ACCELERATOR PEDAL POSITION SENSOR (APPS) . |
OPERATION
The Powertrain Control Module (PCM) operates the fuel injection system. Various sensors and switches provide the inputs necessary for the PCM to correctly operate these systems. The PCM can adapt its programming to meet changing operating conditions. Fuel is injected into the intake port above the intake valve in precise metered amounts through electrically operated injectors. Under most operating conditions, the PCM maintains an air fuel ratio of 14.7 parts air to 1 part fuel by constantly adjusting injector pulse width. Injector pulse width is the length of time the injector is open. The PCM adjusts injector pulse width by opening and closing the ground path to the injector. Engine RPM (speed) and manifold absolute pressure (air density) are the primary inputs that determine injector pulse width.
The PCM regulates:
- Ignition timing
- Air/fuel ratio
- Emission control devices
- Electric cooling fan
- Charging system
- Idle speed
- Vehicle speed control
The PCM monitors the fuel injector and wiring for electrical faults as well as the voltage spike created by the collapse of the magnetic field in the injector coil.