Recovery

In order to obtain this result the system uses a stepping motor (1) fixed to the butterfly casing assissted by the electronic control unit which, when operating, moves a stem with a shutter (4) which alters the section of the by-pass duct (2) and consequently varies the quantitye of air (Q + Qo) drawn in by the engine.

The electronic control unit uses the engine angular speed and coolant temperature parameters from the respective sensors to regulate this type of action.

Air flow rate from butterfly (constant) - Qo

Air flow rate adjusted by actuator (variable) - Q

Diagram showing supplementary air and idle adjustment actuator

1. Stepping motor
2. By-pass duct
3. Butterfly valve
4. Shutter

Wiring connector

The numbers indicate the corresponding control unit pins.

Recovery

When the control unit detects that the operating current for one or more motor phases increases beyond a certain value, an error is detected and the operation of the actuator is immediately disabled.