Mitsubishi Outlander XL. Manual - part 1246

(injection time). There is a prescribed basic drive time
that varies according to the engine speed and intake
air volume. ECM adds prescribed compensations to
this basic drive time according to conditions such as

the intake air temperature and engine coolant
temperature to decide injection time. Fuel injection is
done separately for each cylinder and is done once in
two engine rotations.

System Configuration Diagram

ZK602750

ECM

Injector

Mass airflow sensor

Manifold sbsolute pressure
sensor

Intake air temperature sensor

Engine coolant temperature
sensor

Throttle position sensor

Crankshaft position sensor

Camshaft position sensor

Knock sensor

Ignition switch-ST

Heated oxygen sensor

AA00

1. INJECTOR ACTUATION (FUEL INJECTION)

TIMING

Injector drive time in case of multiport fuel injection (MFI) is
controlled as follows according to driving conditions.

13A-32

MULTIPORT FUEL SYSTEM (MFI)

FUEL INJECTION CONTROL

Fuel Injection During Cranking and Normal Operation

ZK600287

<No.6TDC>

<No.1TDC>

<No.2TDC>

<No.3TDC>

<No.4TDC>

<No.5TDC>

Camshaft position
sensor signal

H
L

Cylinder Stroke

No.1 cylinder

No.2 cylinder

No.3 cylinder

No.4 cylinder

No.5 cylinder

No.6 cylinder

Intake

Fuel injection

Fuel injection Fuel injection

Fuel injection

Compression

Combustion

Exhaust

AA01

Crankshaft position
sensor signal

Fuel injection to each cylinder is done by driving the injector at
optimum timing while it is in exhaust process based on the
crankshaft position sensor signal. ECM compares the crankshaft
position sensor output pulse signal and camshaft position sensor
output pulse signal to identify the cylinder. Using this as a base,
it performs sequential injection in the sequence of cylinders 1,
2, 3, 4, 5, 6.

Additional Fuel Injection During Acceleration

ZK600288

<No.6TDC>

<No.1TDC>

<No.2TDC>

<No.3TDC>

<No.4TDC>

<No.5TDC>

H
L

Cylinder Stroke

No.1 cylinder

No.2 cylinder

No.3 cylinder

No.4 cylinder

No.5 cylinder

No.6 cylinder

Intake

Compression

Combustion

Exhaust

AA01

Increase injection for acceleration

Crankshaft position
sensor signal

In addition to the synchronizing fuel injection with crankshaft
position sensor signal during acceleration, the volume of fuel is
injected according to the extent of the acceleration.

MULTIPORT FUEL SYSTEM (MFI)

13A-33

FUEL INJECTION CONTROL

2. Fuel injection volume (injector drive time)

control

The figure shows the flow for injector drive time calculation.
Basic drive time is decided based on the airflow sensor signal
(intake air volume signal) and crankshaft position sensor signal
(engine rotation signal). This basic drive time is compensated
according to signals from various sensors and optimum injector
drive time (fuel injection volume) is calculated according to
driving conditions.

Fuel Injection Volume Control Block Diagram

ZK600289

Mass airflow sensor

Crankshaft
position sensor

Heated oxygen
sensor

Engine coolant
temperature
compensation

Engine coolant
temperature sensor

Manifold absolute
pressure sensor

Fuel pressure
compensation

Barometric pressure
sensor

Battery voltage
compensation

Battery voltage

Basic fuel
injection time
determination

Air fuel ratio
compensation
(Predetermined
compensation)

Heated oxygen
sensor feedback
compensation

Injector

Acceleration-
deceleration
compensation

AA00

13A-34

MULTIPORT FUEL SYSTEM (MFI)

FUEL INJECTION CONTROL

[Injector basic drive time]
Fuel  injection  is  performed  once  per  cycle  for  each  cylinder.
Basic  drive  time  refers  to  fuel  injection  volume  (injector  drive
time) to achieve theoretical air-fuel ratio for the intake air volume
of 1 cycle of 1 cylinder. Fuel injection volume changes according
to  the  pressure  difference  (injected  fuel  pressure)  between
manifold pressure and fuel pressure (constant). So, injected fuel
pressure  compensation  is  made  to  injector  drive  time  for
theoretical air-fuel ratio to arrive at basic drive time.

ZK600290AA00

Basic fuel
injection time

Fuel injection pressure compensation

Intake air amount per cycle per cylinder

Theoretical air-fuel ratio

Intake air volume of each cycle of 1 cylinder is calculated by ECM
based on the airflow sensor signal and crankshaft position
sensor signal. Also, during engine start, the map value
prescribed by the coolant temperature sensor signal is used as
basic drive time.

[Injector drive time compensation]
After calculating the injector basic drive time, the ECM makes
the following compensations to control the optimum fuel injection
volume according to driving conditions.

List of main compensations for fuel injection control

Compensations

Content

Heated oxygen sensor feedback compensation

The heated oxygen sensor signal is used for making
the compensation to get air-fuel ratio with best
cleaning efficiency of the 3-way catalytic converter.
This compensation might not be made sometimes
in order to improve drivability, depending on driving
conditions. (Air-fuel ratio compensation is made.)

Air-fuel ratio compensation

Under driving conditions where heated oxygen
sensor feedback compensation is not performed,
compensation is made based on pre-set map values
that vary according to engine speed and intake air
volume.

Engine coolant temperature compensation

Compensation is made according to the engine
coolant temperature. The lower the engine coolant
temperature, the greater the fuel injection volume.

Acceleration/ Deceleration compensation

Compensation is made according to change in
intake air volume. During acceleration, fuel injection
volume is increased. Also, during deceleration, fuel
injection volume is decreased.

MULTIPORT FUEL SYSTEM (MFI)

13A-35

FUEL INJECTION CONTROL

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