Supercharging Control Valve - Fiat Bravo Service Manual

Bravo-Brava

Supercharging control valve

The function of the supercharging control valve is to adjust the value of the maximum fuel f l o w rate ac-
cording to the variations in the pressure of the intake air created by the turbocharger.
The supercharging control valve is composed of a valve body (1) which contains a piston (2) w h i c h
rests on a spacer (3).
There are t w o different size diaphragms (4) at each side of the spacer ( 3 ) .
The supercharging pressure, produced by the turbocharger, enters between the two diaphragms via the
connector (7).
The supercharging valve is fitted in the transfer pressure circuit somewhere between the transfer pump
and the supplementary f l o w rate device.
It varies the pressure acting on the supplementary device pistons according to the pressure of the air
supplied by the turbocharger.
On accelerating the engine speed increases and consequently so too does the pressure produced by the
turbocharger which reaches the supercharing control valve gradually moving the diaphragms (4) w h i c h
compress the spring (5).
The valve piston (2) moves opening the discharge port (8) producing a drop in pressure behind the sup-
plementary flow rate device pistons.
Under these circumstances the supplementary device spring can gradually thrust the system towards
the "supplement engaged" position.
This movement allows the control valve piston (2) to gradually open a port (8) which allows the fuel to
be discharged via the diesel return pipes to the vehicle tank and makes it possible to reduce the pressure
w h i c h builds up upstream of the supplementary device pistons.
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Copyright by Fiat Auto
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TD 100
IX-96 - Ctinculi. cincl iitplau.-<i
1. Valve body
2. Piston
3. Spacer
< z )
4.
Diaphragms
5. Spring
6. Adjustment screw
7. Connector for the super-
charging pressure
®
Discharge of the transfer
8.
pressure
9. Recovery connector
P4A13EJ01
E n g i n e
Fuel system
10.
13