Mitsubishi Evolution X. Manual - part 129

MULTIPORT FUEL INJECTION (MFI) RELAY CONTROL

TSB Revision

MULTIPORT FUEL SYSTEM (MFI)

13A-45

Thus, by operating the turbocharger wastegate solenoid under 
duty cycle control, the ECM is able to control the intake charge 
pressure within a duty cycle range of 0% to 100%. The ECM 
actuates the turbocharger wastegate solenoid 1 at a duty cycle 
rate that suits the engine speed and throttle valve opening 
angle, and actuates the turbocharger wastegate solenoid 2 at a 
duty cycle rate that suits the engine speed. By operating a com-
bination of two turbocharger wastegate solenoid, the ECM is 
able to control a wide range of intake charge pressure.

MULTIPORT FUEL INJECTION (MFI) RELAY CONTROL

M2132006000388

When the ignition switch-IG "ON" signal is input, 
ECM turns ON the power transistor for control of the 
MFI relay. As a result, current flows through the MFI 
relay's coil, the relay switch turns ON and power is 
supplied to each sensor and actuator. Also, when 
ignition switch-IG "OFF" signal is input, ECM per-
forms the following controls and then turns OFF the 
power transistor for control of MFI relay.

• Initializing control of throttle valve

• After run control of fan for cooling

AK501260AF

Intake
charge
pressure
kPa (in.Hg)

When turbocharger
wastegate solenoid is
always in "ON" position

When turbocharger
wastegate solenoid is
always in "OFF" position

AK604134AB

OFF

ON

IG2

ST

LOCK

ACC

IG1

MFI relay

Power
supply

MFI relay control

Ignition switch-IG

Battery
back up

To each sensor and
actuator

Ignition switch

ETACS-ECU

Battery

E

CM

FUEL PUMP RELAY CONTROL

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MULTIPORT FUEL SYSTEM (MFI)

13A-46

FUEL PUMP RELAY CONTROL

M2132006500424

AK702866

M

Battery

AE

OFF

ON

IG2

ST

LOCK

ACC

IG1

ETACS-ECU

ECM

Fuel pump
relay 2

Crankshaft position sensor

Ignition switch

Ignition switch-ST

Fuel pump
relay 2 control

MFI relay

OFF

ON

Fuel pump
relay 1 control

Fuel pump
circuit resistor

Fuel pump
relay 1

To ECM

OFF

ON

Fuel pump

FUEL PUMP RELAY CONTROL

TSB Revision

MULTIPORT FUEL SYSTEM (MFI)

13A-47

When the ignition switch-ST signal is input, ECM 
turns ON the power transistor for control of the fuel 
pump relay 2. As a result, the fuel pump relay 2, 
which is integrated in the ETACS-ECU turns ON, 
supplying power to the fuel pump. Also, the ECM 
turns the fuel pump relay 1 ON or OFF in accordance 
with the driving conditions of the engine, in order to 
switch the actuation condition (High or Low) of the 
fuel pump. If the engine speed is low, the ECM turns 
OFF the fuel pump relay 1. As a result, the current 
travels through a fuel pump circuit resistor to the fuel 
pump. Because the voltage that is applied to the fuel 
pump is reduced by the resistor, it decreases below 
battery voltage. This results in a lower fuel pump 
speed, which reduces the fuel supply volume. If the 
engine speed is high, the ECM turns ON the fuel 
pump relay 1. As a result, there is no voltage drop 
caused by the fuel pump circuit resistor, allowing the 
fuel pump to operate at high speeds. Thus, the fuel 
supply volume increases. Also, if engine speed falls 
below a set value, the fuel pump relay is turned OFF. 
Thus, it deals with sudden stoppages such as engine 
stalling etc. by stopping the pump.

STARTER RELAY CONTROL

TSB Revision

MULTIPORT FUEL SYSTEM (MFI)

13A-48

STARTER RELAY CONTROL

M2132025500274

When the ignition switch-ST signal is input, ECM 
turns ON the power transistor for control of the 
starter relay.

AK702867

M

AD

OFF

ON

OFF

ON

ECM

Starter relay
control

ETACS
-ECU

Ignition switch-ST

Battery

Starter relay

Starter

<M/T>

Clutch
interlock 
switch

Shift lever
position
switch (P)

Shift lever
position
switch (N)

Shift lever

<TC-SST>

OFF

ON

OFF

ON

OFF

ON