THROTTLE VALVE OPENING ANGLE CONTROL AND IDLE SPEED CONTROL



Engine-ECU 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 compensations and controls the throttle valve opening angle according to the target opening angle.



While starting


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

While idling


Engine-ECU controls the throttle valve to achieve the target opening angle that are set based on the engine coolant 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.

List of main compensations for throttle valve opening angle and idle speed control


Compensations
Content
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, engine-ECU compensates the throttle valve opening angle based on that difference.
Atmospheric pressure compensation
At 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 compensation
Compensation is made according to the engine coolant temperature. The lower the engine coolant temperature the greater the throttle valve opening angle.
Electric load compensation
Throttle 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 functioning
Throttle 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.

Initialize control


After ignition switch turns OFF, engine-ECU drives the throttle valve from fully closed position to fully open position 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.

Engine protection control


When the racing is continued during the vehicle stopped period (no-load period) for more than the specified time, the engine-ECU closes the throttle valve and restricts the engine speed to protect the engine.