Hatchback 4WD F4-1781cc 1.8L (1983)
Pulsed Secondary Air Injection: Description and Operation
Air Suction System
Fig.3 Air suction system.
The purpose of the air suction system, FIG. 3, is to reduce HC and CO emissions during low-speed and light load operation by supplying necessary
amounts of air into the exhaust ports.
The operating principle of the system is based on a utilization of the negative pressure caused by exhaust gas pulsation and intake manifold pressure
during valve overlap period.
The gas pressure in each exhaust port is transmitted to the air suction valve through the air suction hole and air suction pipe. When pressure transmitted
is negative, the reed valve of the air suction valve is opened towards the valve stopper and simultaneously fresh air is drawn from the air cleaner through
the air suction hose and silencer into the exhaust port. When positive pressure reaches the air suction valve, the reed is closed in an instant to prevent the
flow of exhaust gas into the valve assembly
