Evaporative Emission Control System; Egr System - Saab 1992 900 Owner's Manual

Car care and technical information 67
Evaporative emission control
system
A sealed fuel system is used to prevent the
emission into the atmosphere of vapors
from the stored gasoline supply. Evapo ­
rated fuel is vented from the fuel system to
the storage canister which is connected to
Sealed fuel system
1 Fuel lank
2 Fuel tank vent lines
3 Ventilation line to storage canister
4 Inlet air
5 Storage canister
6 Inlet air and gas vapors
7 Inlet manifold
8 Check valve
9 Rollover valve
9
SG 571
the throttle housing. The evaporated fuel is
purged from the storage canister and
burned by the engine when it is running.
EGR system (if equipped)
Exhaust gas recirculation (EGR) is em ­
ployed on certain models to reduce forma­
tion of oxides of nitrogen by introducing a
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Electronic EGR
1 LH-system ECU
2 EGR valve
3 Temperature sensor
4 EGR pipe
5 Modulating valve
6 Turbo
7 Vacuum lank
8 Non-return valve
9 Exhaust manifold
10 Bypass valve
small amount of downstream exhaust gas
to the intake charge to lower the peak com ­
bustion temperature. Exhaust gases are
routed from the exhaust manifold through a
valve controlled by the LH electronic con­
trol unit and are introduced in the intake
manifold. The electronic control unit also
controls system operation according to the
working temperature of the engine.