check valve 1 way or 2?
 

OK the check valve that is in the line going to the pressure chamber... Is it a 1 or 2 way check valve?

How does a 2 way check valve work?

well it allows 2 different amounts of vaccum to flow from each side like the ones on our cars... If you hook up a vaccum pump on one side @ 5kPa it should flow one way and on the other side @ 6kPa it should flowthe other way. Does that make sense?

Yep. Unfortunately, I don't know the answer to your qestion. But I can't recall anyone mentioning a 2-way check valve being used on the car. Try searching the forum and Robinette's and Ciriani's sites for more info.

They are all 1-way.

If you're talking about the check-valve looking thing that goes to the MAP sensor on the firewall, it's supposed to flow both ways. The Mazda vacuum diagram calls it a gas filter. I guess its supposed to keep crap out of the MAP sensor. I think someone else on this list also said that it helps smooth out changes in vacuum too, or something like that.

Wait... I just re-read your post, and you said the line that goes to the pressure chamber. The big black box thing? Besides the thing that goes to map sensor, all the other valves are one way.

The one going to the pressure chamber requires you to blow pretty hard if you are testing the old fashioned way. It will not flow in the other direction. You won't hear anything move inside like the others. I just spent $29 CDN for a new one cause I kept breaking the old.:D