Toyota 4-Runner 1985 Repair Manual page 149

EMISSION CONTROL SYSTEMS (CARB.) - High Altitude Compensation (HAC) System EC-49
EC0376
~l'
No Air
EC0377
Sub-diaphragm
Plug
~
EC0378
EC0380
INSPECTION OF HAC SYSTEM
PRECHECK:
Before checking the HAC system, determine the position
of the HAC valve. This can be done by blowing into any
one of the three ports on top of the HAC valve with the
engine idling. If the passage is open, the valve is in the HIGH
ALTITUDE position.
If.it is closed, the valve is in the LOW ALTITUDE position.
A. AT HIGH ALTITUDE
1. CHECK IGNITION TIMING AT IDLE
(a) Warm up the engine.
(b) Disconnect the hose from the distributor subdi-
aphragm, and plug the hose end.
(c) Check the ignition timing.
Ignition timing: 0° BTDC
@
Max. 950 rpm
(d) Reconnect the hose to the sub-diaphragm.