Aspirator Air System: Operation

The aspirator valve draws fresh air from the "clean" side of the air cleaner, past a 1-way, spring-loaded rubber diaphragm. The diaphragm opens to allow fresh air to mix with the exhaust gases during negative pressure (vacuum) pulses, which occur at the exhaust ports and manifold passages.

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

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