W150 1/2 Ton Pickup 4WD V8-318 5.2L VIN R 4-bbl (1982)
Pulsed Secondary Air Injection: Description and Operation
Fig. 9
PURPOSE
To reduce CO and HC emissions.
OPERATION
This valve uses exhaust pressure pulsations to draw air into the exhaust system to reduce CO and HC emissions.
It draws fresh air from the "clean" side of the air cleaner, past a one-way spring loaded diaphragm. The diaphragm opens to permit fresh air to mix
with the exhaust gases during negative pressure--vacuum--pulses. When the pressure is positive, the diaphragm closes and no exhaust gases are
allowed to flow past the valve.
The aspirator valve works most efficiently at idle and slightly above idle when the negative pulses are maximum.
At higher engine speed, the aspirator valve remains closed.
NOTE: 1982 vehicles equipped with V8-318 engines have two aspirators.
