Computers and Control Systems: Description and Operation

Purpose
The electronically controlled Multiport injection system (ECI-MULTI) maintains emission levels and fuel economy within government agency standards, while optimizing driveability. The system consists of an Electronic Control Module (ECM), Multiport Fuel Injection Control (MFI) relay, wiring, sensors and actuators.

Operation
The ECM uses an 8-bit microprocessor, random access memory (RAM), read only memory (ROM) and an Input/Output (I/0) interface. The MFI supplies positive current to the purge solenoid, ECM, and injectors. It also supplies current to the fuel pump during starting.

The system also performs self-diagnostic procedures and provides back-up functions if certain circuits fail.

Sensors/Inputs
- A/C control unit
- Air flow sensor (AFS)
- Barometric pressure sensor
- Battery voltage
- Coolant temperature switch (A/C only)
- Crank angle sensor
- EGR temperature sensor
- Engine coolant temperature sensor
- Idle position switch
- Ignition switch
- Ignition timing adjustment connector
- Inhibitor switch (A/T only)
- Intake air temperature sensor
- Oxygen sensor
- Power steering load switch
- Throttle position sensor
- Vehicle speed sensor
- Camshaft (TDC) sensor

Actuators/Outputs
- A/C relay
- Diagnostic check connector
- EGR solenoid
- Fuel injector
- Fuel pump
- Fuel Pump Drive Terminal
- Idle Air Control (IAC) motor
- Malfunction indicator light
- Power transistor
- Purge control solenoid