Ok so thanks to my fellow b5 owners here I found out that I need a new n75 valve. Until I can get a new one, I disconnected the vacuum line that connects in front of the IM in order to stop the erratic boost. Well, today I was looking at where the line connects to and noticed that its connected to the same module where the vacuum for the DV is connected. Does this mean that I'm also not allowing the DV to function properly? I don't want to ruin the turbo by driving around like this if that's the case. TIA.

 

Are you saying that the line coming off the front of the IM doesn't go right to the DV?

What "module" are you talking about?

 

If it's shutting down the DV's function and not allowing it to recirculate, chances are in the short term you'll be fine. At or near stock boost levels, you're not moving enough air for the backsurge to do damage. Worst case is you may see some lag as you hit the gas in the next gear due to the boost air reverse-flowing toward the turbo and creating a counterpressure against the airflow coming toward the engine. It may slow the turbo slightly but I doubt you'll hurt anything.

 

So yours goes directly to the DV?? I actually have two little metal boxes that connect under the IM. One is for the IM and DV and the other one is for the EGR valve I think and I forgot which one is also interconnected to a tube that connects to the suction pump. Each box is hooked up to wires too which looks like the same type of connection that the n75 has.

Ok, so if this is the case then 5 lbs. of boost shouldn't really do any damage then. But I'm guessing it would shorten the life of the turbo then if I were to just leave it like this? What if I just hooked up a line directly to the DV from the IM like lm0812 was saying?

 

Must be an AWM vs AEW difference, mine does run right to the DV.

I don't see any reason why you shouldn't do the same on yours until you get your problem solved.

Personally, I wouldn't want to run without a DV even at stock boost levels at all if its avoidable. It was installed from the factory for a reason.

 

If you just run a vac line to your DV, you should be ok, but flutter is sexyyyy

 

LM0812, I agree with you that it's much better to run with it - my only point was that it'd likely be ok for a bit without it. You're definitely right that it's better to run with it.

I'm not familiar with those boxes eitherbut as stated above, tapping into any vacuum line at the manifold will give the proper pressure reference for it to work right.

 

Actually its a ndbw(AEB) vs DBW(2000+) thing. Most DBW owners end up bypassing that valve and running the line directly from the front of the IM to the DV like it is on the AEB. The valve under the IM allows the ECU to open the DV as a safety feature to control over boosting.

On the DBW cars another thing that the ecu can do to cause erratic/lower boost is to close the throttle body and this is also done to control boost/power.

 

This is how my vacuum setup is and how I recommend it. It involved getting the SAI blockoff plate from Integrated Engineering and my tune from K0mpressd tuned out the SAI codes so I have no CEL. For the blockoff plate, you can use any piece of metal that is straight, thick enough (1/8" perhaps) to not flex, and use some high temperature RTV around (not covering) the hole. I didn't feel like fabricating even that simple piece so I just bought it. It goes where the kombi valve goes. You can ignore the SAI stuff in this if you want, though.

 

I have a hand full of the IE SAI block off plates in stock. But that is not needed when just bypassing the N249 valve to keep it from controlling the BPV.