Saab 1987 900 Owner's Manual page 46

44 Technical description
B Electronic injection system (LH), 16 valve engines
20
19
d:::==:::::I.
S G483
1.
Fuel tank 11.
Inlet manifold
2.
Fuel pumps
3.
Fuel filter
12.
Throttle switch
13.
Idle speed actuator (AIC)
4.
Fuel pipe 14.
Airmass meter
w/hot
wire
5.
Pressure regulator
6.
Electronic control unit
15.
Heated oxygen sensor
16.
Overpressure switch (Turbo only)
7.
Ignition distributor
8.
Temp. transmitter (NTC)
17.
Relay system
18.
Fuel pump relay
9.
Injection valves
(4)
10. Vacuum hose
19.
Battery
20. Ignition switch
C. Decel dashpot (automatic transmis-
sion, 8 valve/all 16 valve)
The decel dash pot acts upon the throttle
mechanism to minimize incomplete com-
bustion during engine deceleration.
D. Decel fuel shutoff (manual trans-
mission only, 8 valve)
A solenoid operated air by-pass valve redu-
ces air flow in the air flow sensor, lowering
the fuel distributor plunger interrupting
fuel flow during deceleration. The solenoid
is controlled by an engine speed relay and a
throttle contact switch. During decelera-
tion at engine speeds above 1575 RPM the
solenoid opens the by-pass valve. When the
speed drops below 1375 RPM the system de-
activates allowing normal operation.
E. Lambda control system (8 valve)
The Lambda control system is a closed loop
feedback system adapted to the
C.l.
System
to constantly maintain close air/fuel ratio
control under all operating conditions. At
an air/fuel ratio of14.5 to one (Lambda
=
1
at this ratio) , all three regulated pollutants
(unburned hydrocarbons, carbon monox-
ide, oxides of nitrogen) may be simultaneo-
usly controlled efficiently by a special thre-
eway catalyst. An oxygen sensor in the