Description And Operation
The ETC (Electronic Throttle Control) system has been designed for controlled ignition engines; it is formed by the throttle body, by the potentiometer on the accelerator pedal and by the control unit. The throttle body includes the actuator, the throttle valve and the valve position sensor (potentiometer) incorporated in a single casing.
The actuator is formed by a direct current motor with dual stage gear; the throttle body lasts about 15 years, with a minimum distance covered of 250, 000 km.
The MED 17.3.3 system operates the motorised throttle according to the drive torque request.
The torque request can, for example, be evaluated according to the signal coming from the accelerator pedal; this signal is processed by the Engine Management Node, which then determines more or less sharp opening curves.
The throttle is opened by a direct current motor with a PWM signal that is built into the throttle body. The opening of the throttle occurs between 0° and 80° thereby including the adjustment of the idle speed.
The throttle body is equipped with two built-in potentiometers, each of which controls the other. In the event of the failure of both potentiometers or a power supply failure, the Engine Management Node reduces the drive torque according to the position of the accelerator pedal:
- Fully depressed, the supply is cut to one or more pistons, until a maximum engine speed of 2, 500 rpm is reached.
- In intermediate positions, the supply is cut to one or more pistons, until an engine speed of less than 1, 200 rpm is reached.
If the throttle body, injection Engine Management Node or intake manifold are replaced, the self-learning procedure must be carried out.