Bronco L6-300 4.9L VIN Y 1-bbl (1983)
Pulsed Secondary Air Injection: Description and Operation
Fig. 79 Thermactor II system (typical)
Fig. 80 Thermactor II pulse air valve operation
Some engines are equipped with this type of exhaust air injection system, Fig. 79, which does not have an air pump. The system uses the natural
pulses of the exhaust system to draw air into the exhaust manifold. The system is regulated by a pulse air valve. The valve, Fig. 80, is connected to the
air cleaner with a hose and to the exhaust manifold with a metal tube. Some pulse air valves closely resemble the standard Thermactor check valves, but
are not interchangeable with them.
When pressure inside the exhaust manifold is more than the pressure in the air cleaner, the reed in the pulse air valve is closed. When pressure in the
exhaust manifold is lower than in the air cleaner, the reed opens and allows air to be drawn into the exhaust manifold.
