# Turbo flutter and lack of boost???



## Majestimatix (Jun 7, 2015)

So I just got an APR stage 1 tune on my 2000 Audi TT 180q with 108k miles. It's been about 3 weeks now and I've been running into some problems. 1st I was getting sputtering when pressing on the gas so I replaced my plugs and coil packs and that fixed that. Now my car seems to be fluctuating in boost and I'm getting a weird fluttering noise when I release the pedal in the low RPM's around 3k. Could I have a bad DV? I heard about the stock ones going out after a tune, especially on cars with high mileage. Or could it be something else like the MAF housing or bad turbo? What else should I expect to go out as I slowly add more HP? Any help would be greatly appreciated.

Thank you


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## bonefish (Aug 8, 2006)

First thing that I replaced in my mk1 TT was the dv. The inside flap is made of rubber so it bound to fail and at 108k miles I would spend 200 bucks and replace that and see it that was the issue.


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## Boulderhead (Oct 21, 2012)

Majestimatix said:


> So I just got an APR stage 1 tune on my 2000 Audi TT 180q with 108k miles. It's been about 3 weeks now and I've been running into some problems. 1st I was getting sputtering when pressing on the gas so I replaced my plugs and coil packs and that fixed that. Now my car seems to be fluctuating in boost and I'm getting a weird fluttering noise when I release the pedal in the low RPM's around 3k. Could I have a bad DV? I heard about the stock ones going out after a tune, especially on cars with high mileage. Or could it be something else like the MAF housing or bad turbo? What else should I expect to go out as I slowly add more HP? Any help would be greatly appreciated.
> 
> Thank you


DV Flutter is likely a bad N249 or some other vacuum leaks resulting in not enough vacuum to hold the DV open (or bad DV). What happens when you let off the throttle is the diaphragm in the DV should get sucked open with the vacuum created by the closing throttle plate and the excess pressure in the intake tract. If there is a leak or your vacuum hoses aren't routed correctly then the DV keeps trying to close (the flutter effect) when it should stay open.

Even good DV's will flutter your hose routing is wrong.. so don't jump to the most expensive conclusion first.

Pull the DV out and push up on the bottom side with your finger and put your other finger over the small nipple. When you remove your finger from the bottom side it should stay put and suck your thump to the small nipple. If not, and it falls back down then you found you culprit.


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## isaiahjw (Apr 25, 2014)

I had a similar problem not long ago but I also had a pressure drop from my turbo to the throttle valve. Got under the car and looked at the charge pipe and it was disconnecting from the pancake pipe. So I fixed that and bought a new dv just to be on the safe side and now there no more flutter or boost leaks


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## TheDeckMan (Sep 26, 2004)

Pressure test the system and use Vag-Com to open the N249. Also check the wastegate to see if its leaking. Whats your requested and actual boost levels on a 3rd gear log?


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## Majestimatix (Jun 7, 2015)

Okay, so I tried the finger test as stated above. I pushed up from the bottom and held my finger on the top nipple and I got nothing. The thing inside that I was pushing up on was already stuck at the top. Is that normal? My new DV will be arriving tomorrow afternoon so I will be replacing it regardless. Hopefully that will fix my problem. Where is the wastegate located and how do I check it for leaks? Also, which hoses should I check for leaks and where are they located? Would I be better off taking it into a shop for farther inspection? Id rather fix it myself but if it involves something I don't have I might have to spend some money and take it in. I have some boost but I can hear/feel it going in and out when I floor it.


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## nickpiroTT (Jul 26, 2015)

I have a similar problem. My car seems to flutter when I let off the gas going up a hill or building up pressure at low RPM's. At first I thought it sounded cool until I realized I'm not getting any boost being put down. I can hear my turbo spooling up but the boost seems non existent. I'm going the DV. Local audi performance shop has Kayser oem diverter valves. Let me know if you have any luck! By the way what type of DV did you order??


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## Majestimatix (Jun 7, 2015)

nickpiroTT said:


> I have a similar problem. My car seems to flutter when I let off the gas going up a hill or building up pressure at low RPM's. At first I thought it sounded cool until I realized I'm not getting any boost being put down. I can hear my turbo spooling up but the boost seems non existent. I'm going the DV. Local audi performance shop has Kayser oem diverter valves. Let me know if you have any luck! By the way what type of DV did you order??


 I went with the APR R1. Figured since I have an APR tune I might as well go with the APR DV as well..


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## MoarLowATC (Sep 23, 2013)

Please let us know what you find! i have the same issue after doing rods clutch and a new turbo. I have tried a few friends diverters so I am checking vacuum lines next.


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## Majestimatix (Jun 7, 2015)

Okay, so I installed my new DV today. Seems like the fluttering noise is still there (mainly in 2nd gear only around 3k rpm's). It's definitely not as loud as the old one was, but it's still there. It doesn't seem like the boost is fluctuating anymore, but it definitely doesn't seem like it's getting all the boost it should be. I'm thinking it's a vacuum leak but I have no idea how/where to check for that. Any help would be greatly appreciated!! Thank you


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## Majestimatix (Jun 7, 2015)

Could it be my N75 valve? My stock one does look kind of beat up and old.


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## Majestimatix (Jun 7, 2015)

Been doing a little research and it seems like it may actually be the N75 valve. If not it never hurts to replace an old part. I have a 180q TT with a few mods. 3" 42DD downpipe with custom 3" straight pipe from the cat back. K&N cold air intake. APR R1 diverter valve and APR stage 1 tune. My question is which one should I go with based off the few mods I have. Just a regular N75, N75-J or N75 race? I'm leaning toward the N75-J but just wanna get some other opinions before purchasing..


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## Majestimatix (Jun 7, 2015)

Okay, so I was snooping around my engine today and noticed a hissing noise coming from the N249 hose toward the front of the engine. Replaced that part of the hose with a new one and also replaced the little plastic connector it was connected too. NO MORE HISS, and now my boost seems to be back at a consistent level. I wish I had a gauge to see it's true reading but unfortunately I don't. It's next on my list tho  Anyway, my boost seems to be a little better than it was and it doesn't seem to be fluctuating anymore. Weird thing is tho, now that stupid FLUTTERING noise is back? It was more less gone before I fixed the leak. Just put in a brand new DV, what else could be causing that noise???


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## Marcus_Aurelius (Mar 1, 2012)

^^^ more vacuum leaks is the answer to your question. Pressure test is the only to really locate all the leaks you may have, visual inspection is a shot in the dark. GL!


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## bonefish (Aug 8, 2006)

Turbo in let hose?


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## lite1979 (Sep 9, 2005)

There are two small hoses that attach vertically to the underside if your intake manifold. Iirc, one goes to your N249, and the other goes to your FPR. Check them both. They'll usually fail within months of each other.

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## Majestimatix (Jun 7, 2015)

PROBLEM FIXED!!! So I purchased one of those turbo boost leak testers and did a pressure test on my car. Turns out one of my vacuum lines was completely ripped in half right there under my manifold. Fixed that and now the fluttering noise is completely gone! Was still lacking some boost so I replaced my N75 Valve with an N75J Valve and now my car is better than ever! Turbo spools up very quick. No surging or sputtering. Car is running great now!! Just thought I'd share..

Thanks again for all the help...


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## Marcus_Aurelius (Mar 1, 2012)

Kudos to you for deciding to pressure test to find the problem. Pressure testing is the only sure way to diagnose and fix leak-related problems. But with members always suggesting to visually check this and that hose, it's hard to make everyone understand that visual test is crapshoot. Glad you got it sorted!


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