THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE SPEED CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-38
THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE
SPEED CONTROL
M2132003500328
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.
AK602236AE
Throttle
position
sensorMain
Main Sub
SubMotor drive circuit
A/C switch (CAN) Engine coolant
temperature sensor
Intake air temperature
sensor
Crankshaft position sensor
Power steering pressure
switch
Generator FR terminal
Transmission range
switch (CAN) Motor drive power supply
(From throttle actuator
control motor relay)
Throttle actuator
control motor
Control unit
Barometric pressure
sensor Accelerator
pedal position
sensor
ECM
THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE SPEED CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-39
List of main compensations for throttle valve opening angle and idle speed control
Initialize control
After ignition switch turns OFF, ECM drives the throt-
tle valve from fully closed position to fully open posi-
tion and records the fully closed/open studied value
of the throttle position sensor (main and sub) output
signals. The recorded studied values are used as
studied value compensation for compensating basic
target opening angle when the engine is started next.
CompensationsContent
Stable idle compensation (immediately after start)In order to stabilize idle speed immediately after
start, target opening angle is kept big and then
gradually reduced. Compensation values are set
based on the engine coolant temperature.
Rotation speed feedback compensation (while
idling)In case there is a difference between the target idle
speed and actual engine speed, ECM
compensates the throttle valve opening angle
based on that difference.
Atmospheric pressure compensationAt high altitudes atmospheric pressure is less and
the intake air density is low. So, the target opening
angle is compensated based on atmospheric
pressure.
Engine coolant temperature compensationCompensation is made according to the engine
coolant temperature. The lower the engine coolant
temperature the greater the throttle valve opening
angle.
Electric load compensationThrottle valve opening angle is compensated
according to electric load. The greater the electric
load, the greater the throttle valve opening angle.
Compensation when shift is in D range When transmission is changed from P or N range
to some other range, throttle valve opening angle is
increased to prevent reduction in engine speed.
Compensation when A/C is functioningThrottle valve opening angle is compensated
according to functioning of A/C compressor. While
A/C compressor is being driven, the throttle valve
opening angle is increased.
Power steering fluid pressure compensationThrottle valve opening angle is compensated
according to power steering functioning. When
power steering oil pressure rises and power
steering pressure switch is ON, the throttle valve
opening angle is increased.
STARTER RELAY CONTROL
MULTIPORT FUEL SYSTEM (MFI)13A-48
When the ignition switch-ST signal is input, ECM
turns ON the power transistor for control of the
starter relay.
AK604137
M
AB P
DNR
OFF ON OFF
ON
Engine-ECU
Starter relay
controlTransmission
range switch Ignition switch-STBattery
Starter relay
Starter ETACS
-ECU
