My twin turbos are not acting normally and I'm trying to figure this out. I decided to see if I could find some of the check valves and solenoids to test them. I moved the pressure tank out of the way and I think I found 4 check valves (3 of them in this picture) and 2 of the solenoids.

However, I noticed a tube that looks like maybe there should be a vacuum line attached to it? Should there be something attached to it?

 

According to the vacuum diagram in the 3rd gen FAQ thread stickied in this forum, no. That just vents to atmosphere.

You have seen the 3rd gen FAQ thread right? It is indispensable if you are researching stuff like this.

 

Thanks!

Using the 3rd gen FAQ, under Turbo Troubleshooting, I followed one of the links and found this vacuum diagram: http://www.autosportracetech.com/RX-7/vacuum.jpg

That diagram does not show the "empty pipe", but the diagram in the Vacuum Diagrams thread does: https://www.rx7club.com/showthread.php?p=8113663

I guess I'm going to start off checking the components that I can get at easily like the 4 check valves I can see and the I and J solenoids...

 

Yeah, there are a couple of different versions of that diagram that people have worked on over the years. Some are more clear on certain areas than others. Its always a pita to work on though.