Mitsubishi Evolution X. Manual — part 127

IGNITION TIMING AND CONTROL FOR CURRENT CARRYING TIME

TSB Revision

MULTIPORT FUEL SYSTEM (MFI)

13A-37

IGNITION TIMING AND CONTROL FOR CURRENT

CARRYING TIME

M2132027100205

Ignition timing is pre-set according to engine driving
conditions. Compensations are made according to
pre-set values depending on conditions such as
engine coolant temperature, battery voltage etc. to
decide optimum ignition timing. Primary current con-
nect/disconnect signal is sent to the power transistor
to control ignition timing. Ignition is done in sequence
of cylinders 1, 3, 4, 2.

System Configuration Diagram

AK703692

1

2

3

4

AC

ECM

Mass airflow sensor

Intake air temperature
sensor 1

Engine coolant
temperature sensor

Intake camshaft position
sensor

Crankshaft position
sensor

Throttle position sensor

Knock sensor

Ignition switch-ST

Clutch pedal position switch
<M/T>

Ignition coils

Battery

Spark plugs

Cylinder No.

MFI relay

: Coil driver

IGNITION TIMING AND CONTROL FOR CURRENT CARRYING TIME

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MULTIPORT FUEL SYSTEM (MFI)

13A-38

1. Ignition distribution control

Based on the crankshaft position sensor signal and intake cam-
shaft position sensor signal, ECM decides the ignition cylinder,
calculates the ignition timing and sends the ignition coil primary
current connect/disconnect signal to the power transistor of
each cylinder in the ignition sequence.

2. Spark-advance control and current carrying
time control

.

[During start]

ECM initiates ignition at fixed ignition timing (5

° BTDC) syn-

chronized with the crankshaft position sensor signal.

.

[During normal operation]

After determining the basic spark-advance based on the intake
air volume and engine speed, ECM makes compensations
based on input from various sensors to control the optimum
spark-advance and current carrying time.

AK703693

<No. 2 TDC>

H

L

H

L

<No. 1 TDC>

<No. 3 TDC>

<No. 4 TDC>

<No. 2 TDC>

AC

Cylinder stroke

No.1

cylinder

No.3

cylinder

No.4

cylinder

No.2

cylinder

Combustion

Intake

Exhaust

Combustion

Exhaust

Compression

Intake

Exhaust

Compression

Combustion

Intake

Compression

Intake

Exhaust

Combustion

Compression

Intake camshaft
position sensor
signal

Crankshaft
position sensor
signal

Ignition

IGNITION TIMING AND CONTROL FOR CURRENT CARRYING TIME

TSB Revision

MULTIPORT FUEL SYSTEM (MFI)

13A-39

List of main compensations for spark-advance control and current carrying time control

.

[Control for checking ignition timing]

During basic ignition timing set mode for M.U.T.-III actuator test
function, sparking is done with fixed ignition timing (5

° BTDC)

synchronized with crankshaft position sensor signal.

Compensations

Content

Intake air temperature compensation

Compensation is made according to intake air
temperature. The higher the intake air temperature
the greater the delay in ignition timing.

Engine coolant temperature compensation

Compensation is made according to engine coolant
temperature. The lower the engine coolant
temperature the greater the advance in ignition
timing.

Knocking compensation

Compensation is made according to generation of
knocking. The greater the knocking the greater the
delay in ignition timing.

Stable idle compensation

Compensation is made according to change in idle
speed. In case engine speed becomes lower than
target speed, ignition timing is advanced.

Delay compensation when changing shift

During change of shift, sparking is delayed
compared to normal ignition timing to reduce engine
output torque and absorb the shock of the shift
change.

Battery voltage compensation

Compensation is made depending on battery
voltage. The lower the battery voltage the greater
the current carrying time and when battery voltage is
high current carrying time is shortened.

Delay compensation when depressing clutch pedal

During depression of clutch pedal, sparking is
delayed compared to normal ignition timing to
reduce engine speed.

THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE SPEED CONTROL

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MULTIPORT FUEL SYSTEM (MFI)

13A-40

THROTTLE VALVE OPENING ANGLE CONTROL

AND IDLE SPEED CONTROL

M2132003500500

ECM detects the amount of accelerator pedal
depression (as per operator's intention) through the
accelerator pedal position sensor. Based on pre-set
basic target opening angles it adds various compen-
sations and controls the throttle valve opening angle
according to the target opening angle.

While starting

ECM adds various compensations to the target
opening angle that are set based on the engine cool-
ant temperature, so that the air volume is optimum
for starting.

While idling

ECM controls the throttle valve to achieve the target
opening angle that are set based on the engine cool-
ant temperature. In this way best idle operation is
achieved when engine is cold and when it is hot.
Also, the following compensations ensure optimum
control.

While driving

Compensations are made to the target opening
angle set according to the accelerator pedal opening
angle and engine speed to control the throttle valve
opening angle.

AK702312AE

Throttle
position
sensor

Main

Main

Sub

Sub

Motor drive circuit

A/C switch (CAN)

Engine coolant temperature sensor

Intake air temperature sensor 1

Crankshaft position sensor

Motor drive power supply
(from throttle actuator control
motor relay)

Control unit

Accelerator
pedal position
sensor

ECM

Throttle actuator
control motor

Mass airflow sensor

Barometric pressure sensor

Power steerling pressure switch

Generator FR terminal

Transmission range signal
(CAN) <TC-SST>