I was taking a look at my motor today and I discovered that there was a vac line connected to the black box tucked under the manifold and just laying there. Not sure if its suppose to connect to anything. But when I looked at it more I think that its suppose to connect to the second hose. I labled the pic for you to see. Hose 1 and 2. Let me know thanks.

 

pic 2

 

looks like a broken 1 way valve on hose 1. I think hose 2 is supposed to be like that.

 

Oh really? Do you have any idea where this hose hook up to then? I tried looking for the other half but cant seem to find it. This maybe the reason for the bouncing idle effect. My RPM bounces between 1000rpm and 1500rpm continuously. Does anyone have the vac line Diagram? Thanks

 

Yep, that is definitely a broken one-way valve. You'll need to look and see where the other end fell. That same valve on mine broke about two months ago.
Here's the diagram

 

here is a stock vac diagram that shows the upper vac chamber and the one way valve.

 

I found the other end. I will probably have to glue it or buy a new one. Did it make your car idle all funny?

 

Hose one is a broken valve, BUT hose two is normal. I dont know about you guys, but every fd I have seen has that little breather there.

SOOOOOO correct me if I am wrong, but

hose 1 broken check valve
hose 2 is normal.

.

The vacuum lines out of there either go to the turbo control, or the y-pipe. I beleive that one goes to the turbo control, but dont quote me on that one.



gooduluck,
-josh

 

Yup, the breather on hose 2 is normal for manual tranny cars.

I don't think it matters, but it looks like the 2 hoses on the pressure tank (your "box") are swapped. The one with the check valve goes down under the cross-over pipe -- just pull that off to get to the rest of the line.

btw, what's your boost pattern been like?

 

Don't glue it, just buy a new one at any auto parts store for a couple of bucks. Doesn't have to be a Mazda part. The broken valve didn't affect my idle but it did affect my boost pattern.