General System Description

Purpose
The Mitsubishi electronically controlled multipoint injection system (ECI-MULTI) maintains emission levels and fuel economy within government agency standards, while optimizing driveability. The system consists of an electronic control unit (ECU), control relay, wiring, sensors and actuators.

Operation
The ECU uses an 8-bit microprocessor, random access memory (RAM), read only memory (ROM) and an Input/Output (I/0) interface. The control relay supplies positive current to the purge solenoid, ECU, 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 (Ca. only)
- Engine coolant temperature sensor
- Idle position switch
- Ignition switch
- Ignition timing adjustment connector
- Inhibitor switch (A/T only)
- Intake air temperature sensor
- Detonation (Knock) sensor (Turbo only)
- Oxygen sensor
- Power steering load switch
- Throttle position sensor
- Vehicle speed sensor
- Camshaft (TDC) sensor

Actuators/Outputs
- A/C relay
- Automatic transmission control unit
- Diagnostic check connector
- EGR solenoid (Ca. only)
- Fuel injector
- Fuel pressure control solenoid (Turbo only)
- Fuel pump
- Fuel pump check connector
- Idle speed control servo
- Malfunction indicator light
- Power transistor
- Purge control solenoid
- Wastegate control solenoid (Turbo only)


On-Board Diagnostics
The ECM monitors input and output signals--some are monitored at all times and the others only under specified conditions.

When the ECM detects an irregularity which has continued for a specified time or longer, pa, the ECM memorizes the corresponding trouble code, and outputs the signal to the on-board diagnostic output terminal.
- There are 16 diagnostic items including the normal state, which can be read using a voltmeter or scan tool.

Since trouble code memory is backed up directly by the battery, the diagnostic results are retained even if the ignition key is turned off.
- Trouble codes will, however, be erased when the battery terminal or the ECM connector is disconnected.
- Trouble codes are erased by turning ON the ignition switch and sending the erase signal from the scan tool to the ECM.

For fault code descriptions see Fault Code Identification and Fault Code Descriptions and Set Conditions.

Caution: If a sensor connector is disconnected with the ignition switch turned ON, the trouble code is memorized. If this occurs erase the fault code.