I’m told it’s part of the egr system.
where is it located?
what does it do?

 

https://www.rx7parts.com/products/lh...azda-s11b23-12

Its part of the valve itself. As you have it, it doesn't do anything. It's just junk

 

Thanks for the link, that helped a lot. However, that fits 93-95 fd’s. But the egr valve on my 93 looks like this:

 

That valve was only on 93 California emissions cars and all 94 cars. 95 cars didn't have EGR. That's just the sensor that goes on the EGR valve that tells the ECU "the EGR got the vacuum signal to open, it has opened, system is working right".

It's a fairly rare part now - I don't think you can buy it new and if if fails tough luck.

Dale