Most Mazda piston engines use the conventional air injection system. This system uses a belt-driven vane-type pump to force air through air injection nozzles into the exhaust manifold. The system employs a check valve near the exhaust manifold to keep exhaust gases from traveling back into the air lines if the air pump fails. The system also uses an air control valve which regulates the amount of air sent to the exhaust manifold, increasing it when the vehicle is overrunning (throttle closed at speeds beyond about 20 mph), at which time extra fuel is admitted to the manifold.
Various models replace the air pump with a pulse-type system which utilizes pressure waves in the exhaust system and a reed valve to pump air into the exhaust manifold. Models not using pulse air employ a conventional air pump, a catalytic converter, and a system which protects the converter from overheating by interrupting air flow at high converter temperatures.