PIAGGIO 633823 Service Station Manual page 155

MP3 250 i.e.
1
2 Throttle body and electronic injection control
3 Diagnostics socket connector
4
5
6
7
8
9 Water temperature sensor
10 Injection load remote control
11
MIU injection system
This vehicle is fitted with an integrated injection and ignition system.
Injection is indirect in the manifold through an electro-injector.
The injection and ignition are timed on the four-stroke cycle by means of a tone wheel keyed on to the
crankshaft (24-2 teeth) and pick-up sensor.
Combustion and ignition are managed on the basis of engine revs and throttle valve opening. Further
corrections are made according to the following parameters:
- Coolant temperature.
- Intake air temperature
- Lambda probe strength
The system implements an idle feeding correction with cold engine through a Stepper motor on a by-
pass circuit of the throttle valve. The control unit manages the Stepper motor and the injector opening
time, thereby ensuring the idle steadiness and the proper combustion.
In all conditions of use, mixture preparation is managed by modifying the injector opening time.
The fuel supply pressure is kept constant based on the ambient pressure.
The feed circuit consists of:
- Fuel pump
- Fuel filter
- Injector
- Pressure regulator
Pump, filter and regulator are placed into the fuel tank using a single support.
The injector is connected by two pipes provided with quick couplings. This allows obtaining a continuous
circulation, thereby avoiding the risk of fuel boiling. The pressure regulator is situated at the end of the
circuit.
The fuel pump is controlled by the MIU; this ensures the scooter's safety
The ignition circuit consists of:
TRANSPARENCY
Specification
Fuel injector
unit (MIU)
Battery
Engine rpm sensor
HV coil
Lambda sensor
Fuel pump
Instrument panel
Injection
Desc./Quantity
12V - 12 Ah
INJEC - 3