Toyota COMPUTER-CONTROLLED SYSTEM Training Manual page 180

W
INSPECTION AND ADJUSTMENT - Idle Speed and Idle Mixtur e
( d) Remove the tachometer and SST .
SST 09843-1802 0
6 . ADJUST IDLE MIXTURE (MODELS WITHOUT TWC)
NOTICE : It is
usually
not necessa
ry
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.
(a) Race the engine at 2,500 rpm for approx . 90
seconds .
(b) Insert a testing probe at least 40 cm (1 .3 ft) into
the tailpipe .
(c) Measure the CO concentration for 1 to 3 minutes .
Idle CO concentration : 1 .5 ± 0 .5 %
(cooling
fan off )
If the CO concentration is not as specified, adjust the
idle mixture by turning the idle mixture adjusting screw
in the variable resistor .
• If the concentration is within the specification, this
adjustment is complete .
NOTE : Always check the idle speed after turning the
idle mixture adjusting screw . If it is incorrect, repeat
steps 5 and 6 .
173