Mitsubishi Eclipse. Technical Information Manual (1994) - part 23

ENGINE 

   Control System

CONTROL SYSTEM

N71 BKOOAA

GENERAL INFORMATION

Except the following improvements, the MFI system is essentially the same as the one used on the 1994

4G63 

 DOHC engine.

Major improvements

Remarks

ECU control of the generator is adopted.

Improves idling speed stability electric loads.

ECM control of radiator fan and condenser fan is

adopted.

Basically the same as the one introduced on the 1994

Diagnostic system conforming to OBD-II is adopted.

I

Manifold Difference Pressure (MDP) sensor added to
detect changes in manifold vacuum.

This supports OBD-II EGR monitoring.

ENGINE <TURBO>   Control System

SYSTEM BLOCK DIAGRAM

Sensors

Engine control module (ECM)

Volume air flow sensor

 Fuel injection control

I

I

I

Intake air temperature sensor

I

I

Barometric pressure sensor

Engine coolant temperature sensor

Idle air control

Throttle position sensor

Closed throttle position switch

Ignition timing control

Engine and transaxle

total control

Crankshaft position sensor

Power supply control

Camshaft position sensor

F u e l   p u m p   c o n t r o l

,

Heated oxygen sensor (front, rear)

 Air conditioning compressor

clutch relay control

Vehicle speed sensor (reed switch)

Fuel pressure control

Air conditioning switch

Intake charge pressure control

Air conditioning pressure switch

Turbo meter control

Power steering pressure switch

Electric load switch

Park/Neutral position switch 

Ignition switch-IG

 

 solenoid

Knock sensor

 EGR solenoid control

Transaxle control module (TCM)

 Volume air flow sensor

reset signal control

Manifold differential pressure (MDP)
sensor

,

Cooling fan control

Generator FR terminal

Generator current control

Ignition timing adjustment terminal

Oxygen sensor heater control

Ignition power transistor unit

I

,

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Diagnostic control terminal

Power supply

 

 diagnostic (OBD)

 

Actuators

 No. 1 injector

 No. 2 injector

 No. 3 injector

 No. 4 injector

Idle air control motor

 (stepper motor)

Ignition coil

 (ignition power transistor)

Multiport fuel injection

 (MFI) relay

 Air conditioning compressor

clutch relay

 Fuel pressure solenoid

 Turbocharger waste gate solenoid

 Turbo meter

 EVAP purge solenoid

 EGR solenoid

 Volume air flow sensor

Radiator fan motor relay and air

 conditioning condenser relay

 Generator G terminal

 Oxygen sensor heater

Check Engine/Malfunction

 injector lamp

 Diagnostic output terminal

1-72

ENGINE <TURBO>   Control System

SYSTEM DIAGRAM

 Heated oxygen sensor (Front)

 Volume air flow sensor
 Intake air temperature sensor
 Throttle position sensor
 Closed throttle position switch
 Camshaft position sensor
 Crankshaft position sensor

 Barometric pressure sensor
 Engine coolant temperature sensor

 Knock sensor

 Heated oxygen sensor (Rear)

 Manifold differential pressure sensor

 Power supply

l 

Vehicle speed sensor

l 

A/C switch

 Park/Neutral position switch 
 Power steering pressure switch
 Ignition switch-ST

Intake air temperature sensor

Volume air flow

al injector

 Evaporative emission purge solenoid

a3 Idle air control motor

 EGR solenoid
 Ignition coil, ignition power transistor

 Fuel pressure solenoid

a7 Turbocharger waste gate solenoid

l 

Fuel pump relay

l 

 fuel injection (MFI) relay

l

Air conditioning compressor clutch relay

l

Check engine/Malfunction indicator lamp

l 

Diagnostic output

Idle air control motor

I

Purge control valve

I

Evaporative
emission
canister

 

 

 

 

 

,

 

Evaporative

emission

solenoid

 Engine coolant temperature sensor

 0 Knock sensor

Heated 

sensor (rear)

TWC

Heated oxygen
sensor (front)

 position sensor

Camshaft position sensor

ENGINE <TURBO>   Control System

SENSORS

GENERATOR FR TERMINAL

 Trio diode

Generator

                                                                     

Voltage regulator

I

1 .

Terminal FR of the generator inputs the ON/OFF
state of the generator field coil to the engine control

module. In response to this signal, the engine control
module senses the generator output current, and

drives the ISC servo according to the output current
(electric load). This prevents a change in idling
speed that may otherwise be caused by the electric
load.

The generator generates power when the power
transistor in the voltage regulator is caused to

be ON to supply a current (field current) to the

field coil. When the power transistor is caused
to be OFF, the power generated by the generator

rapidly decreases. The size of the generator

output current, therefore, depends on the ratio
that the power transistor is ON (ON duty). The

Engine control module

 FU0887

voltage at terminal FR is low when the power
transistor is ON, and high when the power tran-
sistor is OFF. Therefore, the ON duty of the

power transistor   the voltage regulator or the
generator output current can be sensed by cal-

culating the ratio that the voltage at terminal

FR is low.

When the generator output voltage reaches the

regulated voltage (approx. 

 the voltage

regulator switches the power transistor from
ON to OFF. When 

 output voltage falls below

the regulated voltage, the voltage regulator
switches the power transistor from OFF to ON.

In this manner, the generator output voltage

is maintained constant.