Toyota 4A-FE Repair Manual page 21

90 Seconds
ENGINE MECHANICAL - Engine Tune-up (4A-FE) EM-23
Tachometer
rpm
EC0163
HC/CO Meter
EM7454
INSPECTION' AND ADJUSTMENT OF
IDLE SPEED AND IDLE MIXTURE
(w/o
TWC)
1.
INITIAL CONDITIONS
(a) Air cleaner installed
(b} Normal engine operating temperature
(c) All pipes and hoses of air induction system con-
nected
{d)
All accessories switched off
{e) EFI
system wiring connectors
fully
plugged
{f) Ignition timing set correctly
(g] Transmission in "neutral" range
(h} HC/CO meter operates normally
2. WARM UP ENGINE
Allow the engine to reach normal operating temperature.
3.
CONNECT TACHOMETER (See page EM-20)
4. CHECK AIR VALVE OPERATION
(See page Fl-131)
5. INSPECT AND ADJUST IDLE SPEED
6.
Idle speed: 800 rpm (w/ Cooling fan OFF)
If not as specified, adjust the idle speed by turning the
IDLE
SPEED ADJUSTING SCREW.
ADJUST IDLE MIXTURE
NOTICE: Always use a HC/CO meter when adjusting
the idle mixture. It is not necessary to adjust with the
idle mixture adjusting screw in most vehicles if they
are in good condition. If a CO meter is not available# DO
NOT ATTEMPT TO ADJUST IDLE MIXTURE.
(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 concentration 1 - 3 minutes after racing
the engine to allow the concentration to stabilize.
Idle CO concentration: 1.5
±
0.5 %
(w/
Cooling fan OFF)