Computers and Control Systems: Description and Operation

Circuit Description
The MPI system controls fuel injection, ignition with selective cylinder knock regulation, idle speed and fuel tank ventilation through a single electronic control unit.

Fuel delivery, idle speed and ignition timing are controlled by the MPI control unit, based on input from these components:
- Air mass sensor
- Coolant temperature sensor
- Oxygen sensor
- Throttle potentiometer
- Idle switch
- Knock sensor #1 and #2
- Engine speed sensor
- Engine reference sensor
- Ignition distributor hall sender

The MPI control unit controls engine management functions through signals to the following output components:
- Electromagnetic fuel injectors with series resistor pack
- Idle stabilizer valve
- Ignition coil with power stage
- Carbon canister frequency valve
- Carbon canister shut-off valve

The MPI system has a permanent fault memory for self-diagnosis.