what is the purpose of this vacuum line?
 

So I just installed a front mount. There is a 1/4inchish sized 3inchesish long vacuum line that goes from the upper manifold on the top side at about 2oclock (if it where a clock), and it goes to the intercoolers back left underside. Its interesting because one side of the line (the manny side) is after the TB and the other (on the ic) is before the tb. Anyone know what this is there for? Does having or not having this set up that way effect idle or anything else for that matter? There are no provisions on the front mount kit for it plumb back in as it was. I was planning on using it as a vacuum source for accessories if possible, but I am unsure. If it matters it's a ser 4 T2.

Thanks in advance for any input

:ttiwwp:

I'm assuming you're talking about the nipple that goes to the air supply valve that's located on the back of the UIM. All this does is increase the idle during hot start or during power steering usage....(similar to the BAC valve) I've never heard of anyone complaining that it didn't work. I'd just cap off the hole and see if it's a problem.

thanks eag8 I appreciate your input. I am sure your right as I did use it as a vacuum source for my boost guage and it seems fine.

For what its worth there is only one vacuum nip on the ic so if you know the answer to the q a picture is not necessary. Eage 8 knew that---thanks homie!

hopefully this will help?
https://cimg3.ibsrv.net/gimg/www.rx7...d1b7a3f267.jpg

Well thats the weird thing I have the same image on hand in my fsm but the vacuum nipple is not there in that image. Its on the top of the upper manny, in that pic it would be just to the right of the fpr. That and the other side of that where it attaches to the underside of the ic are not shown or mentioned anywhere in the fsm.

as Eage8 said earlier, this goes to your Air Supply Valve. When you are sitting at idle, it kicks in when your air conditioning and your power steering are used, to keep the engine from bogging down. When you turn your steering wheel at idle,this kicks in and raises your idle air input to compensate for the transient load. If you are wanting to keep your creature features, such as power steering and have your engine not lug when you do it, leave it there.

You can run that vacuum line from the ASV to anywhere in between the turbo and throttle body. If you are using an aftermarket intercooler, you may have to tap a vacuum nipple into the new piping. Muffler shop should be able to do it in a couple minutes if you don't have tools. It would probably behoove you to take a look at your boost gauge plumbing. That line is used to regulate air from one side of the throttle to the other. If you are wanting the actual boost pressure, take it from the intake manifold, post throttle body. That will tell you the boost your engine is seeing. T-ing off the intercooler for boost pressure, you wont see the vacuum numbers you need, and it's kinda like a stuffed bra, it looks alright, but that's not the real measurement...

If you like not having to keep flogging the throttle while backing out of your driveway, leave this solenoid on and hooked up.

I should have mentioned that the car has no PS or AC. So I havnt had any issues with it. Thanks for all the input guys. I really appreciate it