Aspirator Air System: Operation

Aspirator valve draws fresh air from "clean" side of air cleaner, past a one-way, spring-loaded rubber diaphragm. Diaphragm opens to allow fresh air to mix with exhaust gases during negative pressure (vacuum) pulses, which occur at exhaust ports and manifold passages.

If pressure is positive, diaphragm closes and no exhaust gas is allowed to flow past valve into "clean" side of air cleaner.

Aspirator valve works best at idle and slightly off-idle, when negative pulses are at maximum. At higher engine speeds, valve remains closed.