PIAGGIO MP3 400 i.e., Service Manual, Page: 239 / 394

With the control unit side connector disconnected
and the coolant temperature connector discon-
nected, check the continuity between pin 9 of the
interface wiring harness and the light blue/green
cable of the connector.
Specific tooling
020481Y Control unit interface wiring
020331Y Digital multimeter
Zeroing the throttle
Resetting the throttle valve position signal (TPS reset)
The MIU control unit is supplied with a throttle valve position sensor that is pre-calibrated.
Pre-calibration entails regulating the minimum opening of the throttle valve to obtain a certain flow of
air under pre-set reference conditions.
Pre-calibration ensures optimal air flow to control idling.
This regulation must not be tampered with in any way whatsoever.
The injection system will complete the management of the idling through the Stepper motor and the
variation of the ignition advance.
The throttle body after the pre-calibration has an opened valve with an angle that can vary depending
on the tolerances of the machining of the pipe and the valve itself.
The valve position sensor can also assume various fitting positions. For these reasons the mV of the
sensor with the valve at idle can vary from one throttle body to another.
To obtain the optimum fuel mixture, especially at small openings of the throttle valve, it is essential to
match the throttle body with the control unit following the procedure known as TPS resetting.
With this operation we inform the control unit, as the starting point, of the mV value corresponding to
the pre-calibrated position.
To reset, proceed as follows.
MP3 400 i.e.
Injection
INJEC - 43