Celica Supra L6-2759cc 5M Ser (1982)
Pulsed Secondary Air Injection: Description and Operation
This system is used to direct air into the exhaust port to extend the combustion of unburned hydrocarbons (HC) and carbon monoxide (CO) into
the exhaust system. This air is also used as the oxygen source for the catalytic converter.
Operation
1981-82 4K-C Engine
This system ,draws fresh air from the air suction valve into the exhaust port by using negative pressure created by the overlap of the valves and
pulsation in the exhaust port. When the vacuum acts on the valve, the valve opens and fresh air is drawn in from the exhaust ports of Nos. 1 and 4
cylinders.
1980 3T-C Engine
The operation of this system is controlled by a bi-metal vacuum switching valve which responds to crankcase temperature. When crankcase
temperature is below 42.8° F, the valve is open, closing the air passage in the air suction valve.
When crankcase temperature is above 62.6° F, the valve is closed. When cruising, the vacuum in the two chambers of the air suction valve is
equalized, causing the air passage to open. When vacuum is present at the exhaust ports, the check valve is open and fresh air is drawn into the
exhaust port. When pressure is present, the check valve is closed and fresh air is not drawn in.
During sudden deceleration, the air passage in the air suction valve is closed and air is not drawn in. After a few seconds, vacuum in the chambers
of the air suction valve equalizes through the vacuum transmitting valve, opening the air passage in the air suction valve. The system now responds
as during cruising.
1980 1A-C & 1981-82 3A-C Engine
In this system air is drawn through air suction valve "A" when vacuum is present at exhaust port regardless of intake manifold vacuum. Air is
drawn through suction valve "B" only when intake manifold vacuum is above 5.51 in. Hg. and vacuum is present at exhaust port. The opening and
closing of air suction valve "B" is delayed by the restrictor on 1A-C engine or vacuum transmitting valve on 3A-C engine.
1981-82 Pickup Except California
This system is controlled by a vacuum switching valve and computer which responds to catalytic converter and coolant temperature. The air
suction system operates only when the temperature of the catalytic converter is below 1110° F, and coolant temperature is between 64° and 208° F.
Under these conditions the system momentarily shuts down during sudden deceleration because of high vacuum acting on chamber "A".