17C-11
MR-372-J84-17C000$118.mif
V2
GAS INJECTION
Fault finding - System operation
LPG 3000
Program No: AB
Vdiag No: 08/10
17C
Expansion valve (CNG):
–Purpose:
–It enables the pressure of the gas from the tank to be lowered to a value which is compatible with the injection
system (injectors and temperature pressure sensor downstream from the expansion valve).
–The gas pressure is approximately 3 bar at the expansion valve outlet.
–It regulates the pressure in the injector rail to the pressure in the manifold.
Reducer (LPG):
– Purpose:
–It has the same functions as the expansion valve. Furthermore, it ensures that the fuel switches from a liquid state
to a gaseous state (the gas pressure is approximately 2 bar at the reducer output).
–Operation:
The LPG expansion valve and the CNG reducer are essential components and are composed of:
●a stage for lowering the pressure from 25 bar maximum to a pressure in line with the manifold pressure,
P
output = Pmanifold + 0.85 bars (LPG)
Poutput = Pmanifold + 1.8 bars (CNG with 100 bar of pressure in the tank)
●a pressure regulator, comprised of a system of valves, springs and diaphragms,
●a cut-off solenoid valve,
●a water heating system.
–The expansion solenoid valve
This component controls only supply of gas to the expansion valve. Controlled by the computer, the solenoid valve
allows LPG into the two stages of the expansion valve, thus supplying the LPG injectors.
2. Intersystem connections:
Connections to the other computers:
–Petrol injection computer,
–protection and switching unit
–instrument panel.
