EFI - Functions
of Engine EC
U
LS
signa
l
Correction
ratio
Decreased Increase
d
Engine ECU
Large
Target
curren
t
Smal
l
OHP 57
❑
Idle
mixture
adjustinc
scre
w
OHP 5
7
D-type EFI without oxygen senso
r
L-type EFI without oxygen sensor but with op-
tical Karman vortex type air flow meter or
hot-wire type air flow mete
r
The ECU also reduces CO emissions by
controlling the injection volume in accordance
with the engine speed
.
RELEVANT SIGNA
L
• Lean mixture
sensor (LS)
OHP 5
7
CO EMISSION CONTROL CORRECTION
(D-type EFI'' and L-type EFI'z
)
The injection volume can be adjusted by
manually adjusting the variable resistor (See
page 41)
. This can be used to adjust the volume
of CO emissions
.
RELEVANT SIGNALS
• Variable resistor (VAF)
• Engine speed (NE
)
NOTICE
It is usually
not
necessary to adjust the idle
mixture in most models, provided that the
vehicle is in good condition
. However, if it
does become necessa
ry
to do so, always use
a CO meter
. If a CO meter is not available, it
is best
not
to attempt to adjust the idle
mixture if at
all
possible
.
REFERENCE
When the voltage of the terminal
VAF is 0
.1 V
or less or 4
.9 V or more, the Engine ECU discon-
tinues CO emission control correction
.
Variable resistor
77
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