Passport 2WD L4-2559cc 2.6L SOHC (4ZE1) (1994)
Air Injection Pump: Description and Operation
Secondary (AIR) Injection System
PURPOSE
Provides extra air at the exhaust manifold to improve post-combustion emission reduction.
CONSTRUCTION AND OPERATION
The air pump consists of the pump body, cover, rotor, vanes and relief valve. It is belt-driven by the engine.
Air is drawn through the air cleaner and suction hose into the pump suction chamber. As the rotor turns, the vanes trap the air and carry it to the
outlet chamber and then to the air manifold.
The relief valve is closed by spring tension under most conditions. When pressure exceeds spring tension, the valve opens to release excess air
that would otherwise surpass pump outlet air pressure.