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Air control valve
CalifornIa models
The
air
control
valve
con
troIs
the
quantity
of
secondary
air fed
from
the
air pump
according
to
engine speed
and
load condition
and
prevents
ex
cessive
temperature
rise
of
the
cataly
tic
converter
The
construction
is
as
shown
in
Figure
EC 16
The
intake manifold
vacuum
and
air pump
discharge
pres
sure
applied
to
the
diaphragm
chamber
actuate the
valve which
is
coupled
to
the
diaphragm
and control
the
quanti
ty of
secondary
air
to
be fed
into
the
exhaust manifold
in
response
to
the
engine
condition
c
From
air
pump
To
carburetor
air cleaner
lr
J
EC291
Fig
EC 16 Air control valve
Anti backfire valve
This
valve
is
con
trolled
by
intake
manifold
vacuum
to
prevent backfire
in the
exhaust system
at
the
ini
tial
period
of
deceleration
At this
period
the
mixture in the
intake
manifold becomes
too
rich
to
ignite
and
burn
in
the
combustion
chamber
and burns
easily
in
the
ex
haust system
with
injected
air in the
exhaust manifold
The
anti
backfire
valve
provides
air
to
the
intake
manifold
to
make the
air
fuel
mixture leaner
and prevents
backfire
A
schematic
drawing
of the
anti
backfire
valve
is
shown
in
Figure
EC 17
The anti
backfire
valve inlet is
con
nected
to
the air cleaner and the
outlet
to the intake
manifold
Th
correct
function
of It jS valve
reduces
hydrocarbon
emission
during
aeceleration
If the
valve does
not
work
properly
unburned
mixture
will
be
emitted
Emission
Control
System
from
the
combustion
chambers
and
burns with the
aid of
high
temperature
and
injected
air
which
causes
backfire
I
Tointake
c
manifold
vacuum
I
L
AirdisChaJ1le
I
to
mtake
manifold
From
air
cleaner
ECQ69
Fig
EC 11 Anti back ir
valve
Check valve
A check
valve
is
located
in the air
pump
discharge
lines
The valve pre
ven
ts
the
backflow
of exhaust
gas
which
occurs
in
one
of
the
following
cases
1
When
the air
pump
drive
belt
fails
2
When
relief valve
spring
fails
Construction
is
shown
in
Figure
EC
18
F
rom
m
pump
1
Spring
2
Rubber
valve
3
Seat
Secondary
air
Exhaust gas
EC292
Fig
EC 1B
Check valve
AIr
InJaction
Into axhaust
port
The
secondary
air
fed from
the
air
pump
goes
through
the
check valve
to
the air
gallery
where it is
distributed
to
each exhaust
port
The
secondary
air
is then
injected
from the
air
injection
nozzle
into
the exhaust
port
near
the
exhaust valve
n
L
y
r
V
Air
pump
relief valve
The
air
pump relief
valve
controls
the
injection
of
the
secondary
air into
the exhaust
system when
the
engine
is
EG
11
3
I
Air
gallery
2
Exhaust
port
3
Air
jnjection
nozzle
4
Exhaust manifold
EC293
Fig
EC 19
Air
injection
into exhaust
port
running
at
high speed
under
a
heavily
loaded condition
It
accomplishes
the
following
functions without
affecting
the
effectiveness of
the exhaust emis
sion
control system
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