Boost too high / Diverter Valve question

[mitchelltj1]

Yes, I did a LOT of searching, and have come to the following conclusion... I just want some extra opinions from those with more experience.

I just went stage 3 - and everything has been running great. I did, however, notice a "chirp" a couple times. Then, I realized that the chirp came when my boost pressure was released, and figured that my DVs could possible be going. Soon enough, I noticed that under constant throttle, when the boost would drop, I'd hear the "chirp" noise, then it would repeat a few times in a row, also with a drop of the boost needle.

Now, I notice under WOT the boost seems to jump up way higher... like 24+ where it used to always be around 18... I quickly back off the throttle.

My assumption is that it is a bad or pair of bad DVs. Is this what your opinion would be? Could there be other things to check? F-hose or TBB perhaps? I already have 710Ns, but they are from the previous owner, so I'm not sure how many miles are on them. Thanks in advance for your help.

In the mean time, I assume that it is safe to drive, I've just been keeping my boost to a minimum.

[seadoo4563]

Yes, I did a LOT of searching, and have come to the following conclusion... I just want some extra opinions from those with more experience.

I just went stage 3 - and everything has been running great. I did, however, notice a "chirp" a couple times. Then, I realized that the chirp came when my boost pressure was released, and figured that my DVs could possible be going. Soon enough, I noticed that under constant throttle, when the boost would drop, I'd hear the "chirp" noise, then it would repeat a few times in a row, also with a drop of the boost needle.

Now, I notice under WOT the boost seems to jump up way higher... like 24+ where it used to always be around 18... I quickly back off the throttle.

My assumption is that it is a bad or pair of bad DVs. Is this what your opinion would be? Could there be other things to check? F-hose or TBB perhaps? I already have 710Ns, but they are from the previous owner, so I'm not sure how many miles are on them. Thanks in advance for your help.

In the mean time, I assume that it is safe to drive, I've just been keeping my boost to a minimum.

well first thing you need to do is pressure test.... then come back if there are no leaks

[RolledMySTi]

Pressure test and then drive around and watch your boost. It may be a bad N75 if you are spiking that high.

[seadoo4563]

Pressure test and then drive around and watch your boost. It may be a bad N75 if you are spiking that high.

(or if you are running a MBC)

[mitchelltj1]

No MBC... I'm not exactly sure how to pressure test, but I'm working on it...
My boost builds rapidly and holds fine I believe... It also passes the butt test. I'm guessing that the diverter valve maybe gets stuck open or just has a hole in the diaphragm. I'm learning as fast as possible... seems that vaccuum is ok too.

[seadoo4563]

No MBC... I'm not exactly sure how to pressure test, but I'm working on it...
My boost builds rapidly and holds fine I believe... It also passes the butt test. I'm guessing that the diverter valve maybe gets stuck open or just has a hole in the diaphragm. I'm learning as fast as possible... seems that vaccuum is ok too.

at idle the gauge may appear okay, but a lot of time when u go wot either pressure can open a tear more or when the motor torques back an opens.

today is your lucky day though because this is how you make one
http://www.awe-tuning.com/media/pdf/...ure_tester.pdf

pretty simple to make an operate. make sure u unhook ur pcv valve from the y pipe an take the oil cap off when u start pumping air in. u dont need to make that plg for the pcv hole, i just cover it with my finger.

[mitchelltj1]

OK, here's an update. I haven't done a pressure test yet, but I took the car to the mechanic that did the K04's. We checked the DVs and they same fine... I wish things were that simple. I put another boost gauge on (since mine was getting pinned) and it was displaying 27-28 lbs of boost, then returning to about 19-20. Needless to say, this is too high. It should spike to about 18 and settle about 15 for the Vast stage 3- tune.

Speaking to Vast, they clearly think I have a boost leak (which must have gotten worse in the mean time because I can now hear it), and the computer is over compensating to reach the boost it expects. So... next thing is a pressure test. I really appreciate the help of those who responded. It takes some time learn how to diagnose these things. Thanks!

[mitchelltj1]

Well, unfortunately we did a Pressure Test today, and it held boost everywhere fine... then the hose for the pressure test blew off at 15 psi... so I guess there is no boost leak. The mechanic talked to Vast and it now sounds like it could be the N75... So, gotta order one and hope. Anyone want to chime in?

[archimense]

You should log request boost and N75 duty cycle as I said in another thread recently.

[mitchelltj1]

Thank you. I am going to do that this weekend. I have a new N75 coming today, but I doubt it will help, as I did try to unplug it and experienced the exact same thing... or maybe that means it is just not functioning... hmmm, we'll see

[archimense]

If the N75 fails or is disconnected it will just send boost pressure straight to the waste gate lines causing them to open. So having boost that is too high should not be caused by the N75 in theory.

[mitchelltj1]

^^ Yeah, replaced the N75 with no luck... Anyone need one? :-) So anyhow, guess I got to get reprogrammed... I dunno, I still can't find a leak, but feel as if I can hear an extra whistling sound...

Another curious thing, it sounds occasionally (at idle) like there is a slight high pitched hiss or buzz. At first I thought it was my speakers, but it actually sounds louder outside the car, perhaps near the trunk, or exhaust...

[archimense]

It could possibly be the N249 valve which controls the DVs.

[RolledMySTi]

Any updates on this? I'm having the same problem.

[AE Performance]

Have you tried hooking it up to a vag-com to see if there are any codes being thrown that arent registering a MIL? It is definitely boosting too high. Which software are you running?

Lastly, if you want to upgrade your DV's to Forge 007P valves, let me know as we're still having our special on forge valves.

Good luck with the repair, and definitely check out your TBB carefully as theyre very prone to tearing as well.

[mitchelltj1]

Thanks for the reply. Never know, I may upgrade the DVs but for now, I checked the 710n's and they are fine.

I have bigger problems now... at least 1 bad turbo... hopefully covered under warranty, but I'll probably have to pay labor again. I feel like the shop that did the work, did a lot more harm than I would have, and probably esaserbated the problem by insisting it was software and not something else... I just hope during the rebuild we can diagnose and fix this problem... :-( Anyone else have any suggestions or experience?

I'm running Vast stage 3- software, and they rechecked the map and even nudged the boost down just a hair to make sure...
I have an upgraded TBB and F-hose... We visually inspeceted them, but didn't take them off the car.

[mitchelltj1]

Just an update for anyone that follows this in the future...

Long story short, I was sold cheap knoch-off turbos that went bad in a week. Probably had crappy wastegates and were of poor quality. Working on a refund now and already got Borg Warners in... Just be careful who you buy from people. Especially on ebay. It is an expensive lesson to learn.

[ThirdStrike]

Just an update for anyone that follows this in the future...

Long story short, I was sold cheap knoch-off turbos that went bad in a week. Probably had crappy wastegates and were of poor quality. Working on a refund now and already got Borg Warners in... Just be careful who you buy from people. Especially on ebay. It is an expensive lesson to learn.

ROFL
sux but damn ... not a surprise

[espo4442]

Damn man that sucks, sorry to hear

[jameskkk3]

i just went thru the same thing that you wnet thru no vacume, boost leaks so i tried the n75 and that didnt work so i brought it to audi and one of my wastegates was stuck open so i would start with the n75