Quote:
Originally Posted by dawsonj3
Brian, I have a difficult time accepting that the operation is as simple as you describe. A purely binary operation (vacuum present or vacuum absent) would appear not to require the usage of two different valves which are both influenced by throttle position.
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Here is how it works:
At "closed throttle," Valve A is closed, preventing vacuum from actuating the EGR valve. At slight throttle and higher, Valve A routes vacuum to the EVR valve so that it opens. At near full throttle, Valve B vents the EGR vacuum to the atmosphere so that the EGR valve closes.
So, the two valves combine to operate the EGR valve only when the throttle is in a "middle" position. And they prevent EGR operation at closed throttle and at WOT.
Quote:
Originally Posted by dawsonj3
These valves almost certainly have a specific function as it pertains to the shifting behavior of the transmission- which I don't currently understand.
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That is a common misconception which, undoubtedly, has its roots in the fact that replacing the 3/2 valves often improves transmission performance. The reason for improvement, however, is the fact that a vacuum leak was eliminated, not that the 3/2 valves have a direct role in the operation of the transmission.