Datsun 1980 200SX Service Manual page 92

AI R FLOW SYSTEM
Intake
air
from
the air
cleaner
is
metered at the air
flow
meter
flows
through
the throttle chamber and in to
the intake manifold and then
flows
through
each intake manifold branch
into the
cylinder
Air
flow during
driving
is controlled
by
the throttle
valve located
in
the throttle chamber
During
idling operation the throttle
valve
is in the
almost closed
position
and the air is led
through
the by
pass
line between air pipe
and throttle
chamber In this
case
the
quantity
of
suction air is
adjusted
by
means
of the
idle
speed adjusting screw During
warming
up
operation
the air flow is
bypassed through the
air
regulator
to
increase
engine
rpm
ELECTRICAL FLOW
SYSTEM
The
suction air
flow
varies with the
movement
of
the air
flow
meter
and
the
quantity
of fuel
to be
injected
should be controlled
correctly
in
cor
Injector
11 R
A
respondence with the
present
air
flow
In the EFI
system
the
injection
pressure is held
constant at
250 kPa
2 5 5
kg cm2
36 3
psi
and
the
area
of the
injector
noule hole is also
con
stant
Therefore the fuel injection
quantity
can
be determined
by
the
l
11
I
ENGINE
FUEL
EFISystemOperation
Idle
speed
adjusting
Air
cleaner
screw
0
AirflOwm
ter f
LA S unit
i
I
Throttle
chamber
L
Air
pipe
LAir
by
pass
screw
SEF084
injector
open
valve time
period
The
control unit of
the EFI system
deter
mines this
pulse
width duration
ac
cording to
information
electrical sig
nals from
various
types
of
sensors
thereby controlling
the fuel injection
quantity
L
Vacuum switch California models
Switching
module
Air flOW
o
Air
by
pass
screw
I
Air
temperature
sensor f
s Control unit
SEF085
EF
5