Mitsubishi Colt Ralliart. Manual — part 12

GENERAL INFORMATION

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-2

GENERAL INFORMATION

M1131000102741

The Multipoint Fuel Injection System consists of sen-
sors which detect the engine conditions, the
engine-ECU <M/T> or engine-CVT-ECU <CVT>
which controls the system based on signals from
these sensors, and actuators which operate under
the control of the engine-ECU <M/T> or
engine-CVT-ECU <CVT>. The engine-ECU <M/T>

or engine-CVT-ECU <CVT> carries out activities
such as fuel injection control, idle speed control and
ignition timing control. In addition, the engine-ECU
<M/T> or engine-CVT-ECU <CVT> is equipped with
several diagnosis modes which simplify trouble-
shooting when a problem develops.

FUEL INJECTION CONTROL

The injector drive times and injection timing are con-
trolled so that the optimum air/fuel mixture is sup-
plied to the engine to correspond to the
continually-changing engine operation conditions.
A single injector is mounted at the intake port of each
cylinder. Fuel is sent under pressure from the fuel
tank by the fuel pump, with the pressure being regu-
lated by the fuel pressure regulator. The fuel thus
regulated is distributed to each of the injectors.
Fuel injection is normally carried out once for each
cylinder for every two rotations of the crankshaft. The
firing order is 1-3-4-2. This is called sequential fuel
injection. The engine-ECU <M/T> or
engine-CVT-ECU <CVT> provides a richer air/fuel

mixture by carrying out "open-loop" control when the
engine is cold or operating under high load condi-
tions in order to maintain engine performance. In
addition, when the engine is warm or operating under
normal conditions, the engine-ECU <M/T> or
engine-CVT-ECU <CVT> controls the air/fuel mixture
by using the oxygen sensor signal to carry out
"closed-loop" control in order to obtain the theoretical
air/fuel mixture ratio that provides the maximum
cleaning performance from the three way catalyst.

THROTTLE VALVE OPENING CONTROL

This system electrically controls the opening of the
throttle valve. The engine-ECU <M/T> or
engine-CVT-ECU <CVT> detects the amount of
travel of the accelerator pedal via the accelerator
pedal position sensor, and controls the actuation of
the throttle valve control servo, which is mounted on
the throttle body, in order to attain the target throttle
valve opening that has been predetermined in
accordance with driving conditions.

IDLE SPEED CONTROL

The idle speed is kept at the optimum speed by con-
trolling the amount of air that passes through the
throttle valve in accordance with changes in idling
conditions and engine load during idling.
The engine-ECU <M/T> or engine-CVT-ECU <CVT>
drives the throttle valve control servo to keep the
engine running at the pre-set idle target speed in
accordance with the engine coolant temperature and
A/C and other electrical load. In addition, when the

air conditioning switch is turned off and on while the
engine is idling, the throttle valve control servo
adjusts the throttle valve passes through air amount
according to the engine load conditions to avoid fluc-
tuations in the engine speed.

IGNITION TIMING CONTROL

The power transistor located in the ignition primary
circuit turns ON and OFF to control the primary cur-
rent flow to the ignition coil. This controls the ignition
timing in order to provide the optimum ignition timing
with respect to the engine operating conditions. The

ignition timing is determined by the engine-ECU
<M/T> or engine-CVT-ECU <CVT> from the engine
speed, intake air volume, engine coolant tempera-
ture and atmospheric pressure.

Main

Index

Group

TOC

GENERAL INFORMATION

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-3

SELF-DIAGNOSIS FUNCTION

• When an abnormality is detected in one of the

sensors or actuators related to emission control,
the engine warning lamp (check engine lamp)
illuminates as a warning to the driver.

• When an abnormality is detected in one of the

sensors or actuators, a diagnosis code corre-
sponding to the abnormality is output.

• The RAM data inside the engine-ECU <M/T> or

engine-CVT-ECU <CVT> that is related to the
sensors and actuators can be read by means of
the M.U.T.-III. In addition, the actuators can be
force-driven under certain circumstances.

OTHER CONTROL FUNCTIONS

1. Fuel Pump Control

Turns the fuel pump relay ON so that current is sup-

plied to the fuel pump while the engine is crank-
ing or running.

2. A/C Relay Control

Turns the compressor clutch of the A/C ON and OFF.

3. Oil Feeder Control Valve Control

The engine-ECU <M/T> or engine-CVT-ECU <CVT>

carries out the duty control of the oil feeder con-
trol valve according to the operation condition.
This varies the phase angle of the intake cam-
shaft to optimize the intake valve timing.

4. Fan Motor Control

The revolutions of the cooling fan is controlled in

response to the engine coolant temperature and
vehicle speed.

5. Alternator Output Current Control

Prevents alternator output current from increasing

suddenly and idle speed from dropping at times
such as when the headlamp are turned on.

6. Purge Control Solenoid Valve Control

(Refer to

P.17-13

, GROUP 17

− Engine And Emis-

sion Control

− Evaporative Emission Control Sys-

tem).

7. EGR Control Solenoid Valve Control <CVT>

[Refer to

P.17-19

, GROUP 17

− Engine And Emis-

sion Control

− Exhaust Gas Recirculation (EGR)

System].

Main

Index

Group

TOC

GENERAL INFORMATION

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-4

GENERAL SPECIFICATIONS

Items

Specifications

Throttle body

Throttle bore mm

45

Throttle position sensor

Hall element type

Throttle valve control servo

DC motor type, having broshes

Engine-ECU <M/T> or
engine-CVT-ECU
<CVT>

Identification No.

Engine-ECU <M/T>

E6T45193

Engine-CVT-ECU <CVT>

E6T45186

Sensors

Barometric pressure sensor

Semiconductor type

Intake air temperature sensor

Thermistor type

Engine coolant temperature sensor

Thermistor type

Oxygen sensor

Zirconia type

Accelerator pedal position sensor

Hall element type

Camshaft position sensor

Magneto resistance element
type

Crank angle sensor

Magneto resistance element
type

Detonation sensor

Piezoelectric type

Manifold absolute pressure sensor

Semiconductor type

Actuators

Engine control relay type

Contact switch type

Fuel pump relay type

Contact switch type

Injector type and number

Electromagnetic type, 4

Injector identification mark

CDH166

Throttle valve control servo relay

Contact switch type

Oil feeder control valve

Duty cycle type solenoid valve

EGR valve <CVT>

Stepper motor

Purge control solenoid valve

Duty cycle type solenoid valve

Main

Index

Group

TOC

GENERAL INFORMATION

MULTIPORT FUEL INJECTION (MPI) <4A9>

13A-5

MULTI-POINT FUEL INJECTION SYSTEM DIAGRAM
<M/T>

AK600525

1 Oxygen sensor
(front)

4 Intake air temperature
sensor

3 Manifold absolute
presssure sensor

2 Oxygen sensor (rear)

3 Throttle valve control
servo

10 Throttle position sensor

(main)

2 Purge control
solenoid valve

8 Engine coolant
temperature sensor

9 Detonation sensor

7 Crank angle sensor

6 Camshaft position sensor

4 Oil feeder control valve

1 Injector

AB

M

1 Oxygen sensor (front)
2 Oxygen sensor (rear)
3 Manifold absolute
presssure sensor
4 Intake air temperature
sensor
5 Throttle position
sensor

(sub)

6 Camshaft position
sensor
7 Crank angle sensor
8 Engine coolant
temperature sensor
9 Detonation sensor
10 Throttle position
sensor

(main)

1 Injector
2 Purge control
solenoid valve
3 Throttle valve control
servo
4 Oil feeder control
valve

Power supply
Ignition switch-IG
Ignition switch-ST
Accelerator pedal
position sensor
(main)
Accelerator pedal
position sensor
(sub)
Alternator FR
terminal
Stop lamp switch

Engine-ECU

Engine control relay
Fuel pump relay
A/C compressor relay
Throttle valve
control servo relay
Ignition coil
Cooling fan

control

relay

Diagnosis output
Alternator G terminal
Oxygen sensor heater
(front)
Oxygen sensor heater
(rear)

Canister

Air
inlet

Catalytic converter

From fuel
pump

5 Throttle position sensor

(sub)

Barometric
pressure
sensor

Main

Index

Group

TOC