Subaru 1600 Service Manual page 180

2) Oxidation Catalyst
The basic material of the oxidation
catalyst is as follows:
Canada models and 4WD of non·
California models: Platinum (Pt) and
Palladium (Pd)
Non4WD of non-California models:
Palladium (Pd) and Rhodium (Rh)
A thin film of their mixture is applied
onto honeycomb or porous ceramics
of an oval shape (carrier). To avoid
damaging the catalyst, only unleaded
gasoline should be used.
The catalyst is used to reduce HC, CO
in exhaust gases.
3) Exhaust Gas Recirculation
(EGR) System
Exhaust gas recirculation (EGR) sys-
tem is aiming at reduction of NOx by
reducing the top combustion tempera·
ture in cylinders through recirculating
a part of exhaust gas into cylinders.
The EGR valve opens in response to
the engine driving conditions and a
part of exhaust gas flows into cylinders
through the intake manifold.
The vacuum signal to control the EGR
valve is picked up from the port near
the slightly up stream portion of
throttle valve after being modulated
with the atmospheric pressure through
the orifice (EGR leak orifice equipped
models). At the specific wall tempera·
ture of intake manifold or below, the
vacuum signal is modulated with the
atmospheric pressure through the
thermo vacuum valve I.
Additionally for non4WD of non·
California models, the vacuum signal is
modulated with the atmospheric pres-
sure through solenoid valve II at the
specified driving condition.
EGR leak orifice
mm(in}
US.A.
c .....
Cafifomi.
Non-Califomi4
Non"'W
NOlt.cWO
.wo
.""
"""
..
""
4W1>
HUadd
c·w
NT
0.7
-
0.5 0.7 0.1 0.1
D.5
SlL
(0.021) (0.«10) (0.028) (O.oJI) (0.028) (0.020)
AT
-
-
-
- -
- -
NT
-
-
1.0 1.7 1.1
- -
(0.039) (0.061) (0.067)
H/A
AT
-
- 0.1 1.0 -
-
(0.028) (O.ll39)
EMISSION CONTROL SYSTEM
Canada models, California models and 4WD of non·California models
(MT)
rAir cleaner
I
I
I
,
Thermo vacuum}
valve
I
Fig. 5-21
Thermo vacuum
EGR
pipe valve
I
\..#1. #3
Cylinder head
OM-721
I
Non4WD of non-California models
I
(MT)
,
, ,
I
,
L---D--~i
ECM :
Thermosensor
~
#1-#3
EGR
valve
, ,
, ,
I
Solenoid
valve II
L"-D"'~
ECM 1
Thermosensor
*
(AT)
(AT)
LEGR valve
EGR
pipe
\#1, #3
Cylinder head
OM·722
EGR
valve
#1-#3
EGR
ct
pipe
ct
pipe
..
..
GaRb
QR.qt>
" w' /
... l'"
,
r
A10·182
A10·183
Fig. 5·22