I have a S4 TII engine, JDM if it matters. I'm wondering what the original use of this vacuum nipple on the rear of the LIM is.

I pulled my removed vacuum rack/rat's nest out of storage and it doesn't have anything that would connect to this as far as I can tell. It doesn't seem to show up in any of the 'removed emission vacuum layout' diagrams I've seen.

Part two of my question; If it has no other purpose, could I run a line from it to the stock bypass valve/BOV? I've read about teeing off of the pressure sensor hose to run the BOV but also heard that's not optimal. Another option I've seen is adding a nipple to the ACV block off plate, but I don't think my block off plate has enough 'meat' to tap it for a screw-in nipple in the correct location (my understanding is that the nipple must be located over one of the three small holes at the top of the ACV mounting flange of the LIM)

Thanks.

 

it looks like that would work, if you can see it going to the rear runner it will work. if not you should put a boost gauge on it and verify that is sees vacuum and boost.

 

It does indeed run straight into the runner.

But, I've decided to try adding a nipple to my ACV block off plate. I'm going to try soldering in a bit of steel tube to run the BPV, and use the factory nipple on the UIM flange under the BAC for the boost sensor.