Air Injection System: Operation

Negative pressure from exhaust pulsation reaches suction valve through suction pipe. This causes reeds in suction valve to draw open. Secondary (fresh) air from air cleaner is drawn through silencer(s) and into exhaust passages. See Fig 1 or Fig 2 .

When positive pressure is present in exhaust, reeds are closed to prevent reverse flow of exhaust gas.

Fig 1: Air Injection (Justy)

Courtesy of SUBARU OF AMERICA, INC.

Fig 2: Air Injection (Except Justy)

Courtesy of SUBARU OF AMERICA, INC.