Bambam7

I know this has been posted before, a few times actually, but searching back through them I've never found the answer I'm looking for.
The OMP vacuum lines. I don't think they go directly to vacuum, but rather to just metered air- atm. pressure. Not sure though.
Same with the primary and secondary (Same??) fuel injector air bleeds.
I have two nipples on the backside of my throttle body for the lines to hook up to, but I've never known exactly which to hook up. There are actully 3 on top of each other in a line, but the bottom one is sealed from the factory. Of the other two, one feels like almost full vaccum, the other feels like very very weak vacuum-or no vacuum.
I have an S5 NA Throttle bodyI've seen diagrams fo s4 throttle bodies, and I have an FSM diagram of my S5, but you can't tell at all by it.
Anyone have any info as to which of these nipples to use? Both? One teed to both OMP and inj bleeds? What?

Thanks- oh, and the other threads have a lot of people jumping in and saying "Well, I think... or.. Maybe it's.,." No offense to anybody, but thats how it didn't go anywhere... does anyone actually know?? Thanks!

NZConvertible

They suck air in all the time. The vacuum in the manifold or chamber sucks air through passages in the manifold, then through vac lines to the UIM, then through passages in the plunum and TB, with the pick-up point being in front of the throttles. For turbos, under boost the air is obviously blown not sucked, but the principle is the same.

The air mixes with the injected fuel or oil and helps to atomise it. There's debate overhow much benefit this provides, but it's safe to assume Mazda didn't go to all that trouble for nothing. There's certainly no downside to it.

The NA diagrams don't show which nipples these lines connect to, so the best thing to do would be to blow smoke or somthing through the nipples to find out if they're fed from before or after the throttles. You need the UIM, spacer and TB all assembled to do that. The oil nozzle nipple is the big one.

Bambam7

Well, the one nipple is definately a vacuum source.
The other feels like it is usually under very light vaccum, which is odd, and is what makes my wonder if it isn't purely atmospheric pressure air that either of these systmes use.
I think I can tee the lines together and run them both off of the more netral of the two nipples.... and then cap off the vacuum source one....