I have been searching and trying to find out what this device is... I have looked through online tech info and my FSM and EFI bible, and I can't figure it out.. what ever it is, its not connected to anything... its the object on the left that has a wire going to it and is a cylinder type shape...

try looking in the emissions area of the books that you have, those are vaccum controls of some sort

The one on the right isthe control valve for the EGR, the other is a vacuum switching valve

Ok, i think I found the name for it finally, BPT valve, the question is, if the end of this is not connected, what goes on within my vaccum system? I have yet to check if it has suction, it is cold and its dark on the eastcoast. I have considerd this also the possible cause of my richness I suffer from...

I would like to know what the BPT valve is FOR. I was thinking it lets air in so the EGR valve will close up. Otherwise, ithe egr valve will keep opening until the engine stalls.

thx

I take my description back. In the photo, the cylinder on the left is what I have, and I don't know what it is. Hanes book ( p. 220) has a photo of the egr valve & "vac switching valve," but the switching valve is not what's in the above pic.

Using the blue connector on the back part of the intake manifold as a reference point. Are you talking about the item at the 9:00 o'clock position that's attached to the manifold with the flat bracket and (3) screws and (3) bolts??

webdawg1

correct, it has an outlet with is not connected to anything....

The flat bracket is bolted to the side on the intake manifold. The tube coming from the bottom of the mystery valve which goes off to the right (in my 280Z) went across the pass. side to to the vacuum solenoids. the isn't any wire going to it, just a hose on either end.

I haven't removed it as yet until I figure out what it does. I thought it was some kind of vacuum port.

I have that on my 78 and have never been able to find out what it is! It is left out of the picture in the FSM. It seems to pull against the linkage under vacuum. Like Tomohawk says, Haynes show a picture of the vacum switching valve which my car and yours does not have. The BPT (Back pressure transducer) valve is the large round one to the left of the EGR valve. Mine is hooked up differently than yours in that vacuum comes directly from the manifold. I always thought it was just part of the California emmisions stuff. If anyone finds out what this actually does, let me know!

Steven-

I don't have that 'S' tube in the forground. Instead my 280Z has a vacuum head sticking up with several nipples for vacuum, and a rubber tube coming from the mystery valve. These are on my (fastfrog vacuum hose diagram), which is below. Maybe we can contact some Z-specialist to help us with this? It seems to be the key to several things, including how to get rid of egr valve. Assuming it doesn't help to have it still on there.

The thing that pulls on the throttle linkage is a fast-idle doohickey for cars with a/c.

My car has the 'dealer installed' a/c rather than the factory installed setup. It doesn't have some of the things shown in your diagram like the solenoids, the vacuum bottle etc. That 'S' tube is just a vacuum hose. The 'thing that pulls on the throttle linkage' (labeled ? in my picture) is the item that sonofzzap and I are questioning. It doesn't seem to act as part of a fast idle control device (F.I.C.D.) at least not on my car.