2016 – MX-5 – Engine

THROTTLE BODY [SKYACTIV-G 2.0]

Purpose

• The throttle body greatly enhances the control of the intake air amount using the internal drive-by-wire^* throttle valve.

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Drive-by-wire is a mechanism which does not link objects physically using a cable but links them using electrical signals.

Function

• The throttle body opens/closes the throttle valve to control the amount of air supplied to the cylinders.

• The amount and timing of the throttle valve opening/closing are controlled by the PCM.

• If malfunctions have occurred in the throttle valve and the PCM, the accelerator opening angle is maintained at a certain angle to assure a certain level of driving performance.

Construction

• The throttle body is located on the intake manifold.

  

• Drive-by-wire has been adopted in which the accelerator operation and throttle valve operation are not physically linked using a throttle cable.

• The throttle body consists of parts such as a throttle valve, throttle valve actuator, throttle position sensor, and return spring.

• The actuator and throttle valve are continuously engaged by a gear and the throttle valve opening angle is linked with the actuator.

• A throttle position sensor, which is equipped on the same axis as the throttle valve, detects the throttle valve opening angle. For the throttle position sensor, refer to CONTROL SYSTEM. (SeeTHROTTLE POSITION (TP) SENSOR [SKYACTIV-G 2.0].)

• The return spring is continuously engaged with the throttle valve, and a force is applied so that the throttle valve is slightly opened (specified angle).

  

  

Operation

• The actuator continues operating based on the duty signal from the PCM while the ignition is switched on (engine run).

• The throttle valve opening angle is determined by the relations between the actuator operation force and return spring force.

• The actuator operation is reversed when closing the throttle valve to the specified angle or less.

  

• The throttle position sensor continuously outputs the throttle valve opening angle to the PCM while the ignition is switched on (engine off or on), and the actuator opens/closes the throttle valve based on the signals from the PCM.

• If the actuator loses operation force due to a malfunction, such as communication is interrupted between the throttle valve and PCM or power to the throttle valve is cut, the throttle valve opening angle is maintained at the specified angle by the return spring force. As a result, a certain level of intake air amount is assured.

  

• For the drive-by-wire control, refer to CONTROL SYSTEM. (SeeDRIVE-BY-WIRE CONTROL [SKYACTIV-G 2.0].)

Fail-safe

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