F-body-fan

Testing my EGR & Solenoid & finding my solenoid switch might be bad?
When the engine is off, the solenoid appears to be open & passes vacuum both directions (TB side, or EGR side)

With the key on & in diagnose mode, (solenoid energized) it seems it doesn't pass vacuum but rather it leaks, not air tight.

So the question is, is the EGR solenoid air tight? should it either pass vacuum or not pass vacuum with no leakdown, sealed system?

Or is it sort of a dump valve? I was thinking it would be a closed, sealed valve when it is not energized, & a pass through valve when energized (no leaks)

In other words like pinching off the line, stops the flow, but doesn't leak any vacuum from either line.

F-body-fan

I think I found some answers by inspecting my solenoid, but if anyone want to confim that would be great. It would appear that when the engine is not running, the solenoid is not energized, this opens the vacuum port from the TB to the EGR. When the engine's started & idling, the solenoid is energized, blocking the vacuum, but porting the EGR side of the solenoid. Sound about right?

darbysan

That sounds right to me.

F-body-fan

Thanks!

Keith Maloy

Ok so was that no vacuum should leak down with the solenoid energized? I have a questionable solenoid as well and am trying to determine how it was designed to work. If I energize mine it constricts the flow but does not seal it off. Any help would be appreciated. thanks

darbysan

According to my shop manual, the EGR solenoid is normally "Open", allowing vacuum to flow to the EGR valve. The ECM closes the Solenoid, blocking flow to the EGR valve. The solenoid has to "release" the vacuum on the EGR side when this happens, or the EGR valve would remain open. This is why the solenoid vents the EGR side when activated.

HTH