Fiat 1996 Brava Service Manual page 405

Engine Bravo- Brava ifp ro *>o
Fuel system
10.
EXHAUST GAS RECIRCULATION SYSTEM (E.G.R. - Exhaust Gas Recirculation)
This system makes it possible to send part of the exhaust gases to the inlet in certain engine operating
conditions.
This dilutes the fuel mixture with the inert gases lowering the peak temperature in the combustion
chamber: in this way the formation of nitrous oxides (NOx) is contained, with a 30^-50% at the exhaust.
The recirculation of burnt gases is only possible at medium to low loads, when the air/fuel ratio is very
high and the operation of the engine is not penalized by the presence of inert gases in place of the air.
The recirculation system is operated by the electronic control unit (1) which receives input signals from
the potentiometer at the accelerator control lever (on the injection pump) and from the rpm and engine
coolant temperature sensors and provides an output signal to operate the Borg Warner E.G.R. solenoid
valve (2).
The latter, connected to the atmosphere via a small filter (3), transmits a lesser or greater vacuum, ac­
cording to the signal received, coming from the special brake servoc vacuum pump (4) to the Pierburg
E.G.R. valve (5).
If the vacuum is sufficient, this valve opens, placing the exhaust manifold in contact with the inlet mani­
fold.
The quantity of gases recirculated can therefore be varied by regulating the opening of the E.G.R. valve
continuously, using the maps stored in the control unit memory relating to the degree of opening ac­
cording to the signals received.
P4A26EJ01
1. Electronic control unit 4. Brake servo vacuum pump
2. Borg Warner modulating valve 5. E.G.R. valve
3. Filtrino presa atmosferica
A
-
G a s e s
coming from the exhaust manifold
B. Gases sent to the inlet
26
IX-96 - Update
Print no. 506.670/08