Stock A4 Started Making "Turbo Flutter"

[SilentSquid]

Hi guys,

I got in my stock b7 a4 2.0tfsi quattro last night and noticed a strange sound coming off of hard acceleration (or high boost). It sounds IMO like a turbo flutter sound but more hollow. This is the first time I noticed this and drove it soft the rest of the way home. I searched the forums and found a few threads with no helpful responses. I'm not throwing any codes and my car is BONE STOCK. My initial thought was that it's a bad diverter valve but I'm not sure. I can upload a sound byte if that helps.

Thanks in advance for any help.

[EvolutionArmory]

Looking at your DV would be your first logical step.

Flutter happens when your throttle plate closes and the DV doesn’t recirc the air fast enough forcing it back into the turbo. A slow or broken DV is a good place to start looking, especially if you still have an early revision diaphragm DV on a completely stock A4 that hasn’t acted up until now.

Having some sporatic flutter on certain occasions is a normal occurance. If you can get the car to do it quite regularly then I’d say you have a problem.

[EvolutionArmory]

And if it sounds like playing cards in the spokes of a bike wheel or BB’s in a tin can, it’s probably wastegate rattle.

If it sounds softer than that, like an actual flutter sound, I’d look into your DV or the throttle plate on your throttle body for cracks. The throttle body plate can crack but you only really see that on high boost cars, not stock. Not impossible though.

[SilentSquid]

Looking at your DV would be your first logical step.

Flutter happens when your throttle plate closes and the DV doesn’t recirc the air fast enough forcing it back into the turbo. A slow or broken DV is a good place to start looking, especially if you still have an early revision diaphragm DV on a completely stock A4 that hasn’t acted up until now.

Having some sporatic flutter on certain occasions is a normal occurance. If you can get the car to do it quite regularly then I’d say you have a problem.

And if it sounds like playing cards in the spokes of a bike wheel or BB’s in a tin can, it’s probably wastegate rattle.

If it sounds softer than that, like an actual flutter sound, I’d look into your DV or the throttle plate on your throttle body for cracks. The throttle body plate can crack but you only really see that on high boost cars, not stock. Not impossible though.

Here's a DropBox link to the sound:

https://www.dropbox.com/s/6nym2zzbpp...0Byte.mp3?dl=0

To me it sounds more like an actual flutter as opposed to the "bb's in a tin" and the sound is recreatable every time I accelerate hard and then let off - regardless of the gear. Thanks for your input and I'll crawl under there after work to see if I can figure it out. I changed my oil on Friday, is there anything (like a hose) that I could have disconnected by mistake that would lead to this. The car is a 2006 so I'm assuming it has the rubber diaphragm, but I've only had it for 6 months so I don't know if the previous owner switched it out.

Thanks again.

[2006b7a4]

My 2006 with the diaphragm DV had the same problem and sounded exactly the same as yours. I replaced it with the Rev. D diverter valve ( https://www.europaparts.com/diverter...6h145710d.html ) and it fixed the problem entirely.

[SilentSquid]

My 2006 with the diaphragm DV had the same problem and sounded exactly the same as yours. I replaced it with the Rev. D diverter valve ( https://www.europaparts.com/diverter...6h145710d.html ) and it fixed the problem entirely.

Thank you so much. I ordered the Rev. D DV yesterday and am going to replace it this weekend (along with checking that pesky cam follower ).

[80sGuy]

Look under your car and inspect all cv axle 'boots' for tears, especially the inner ones. Look for grease residue. If all is well then check the DV. But by all means check your boots first!

[SilentSquid]

Look under your car and inspect all cv axle 'boots' for tears, especially the inner ones. Look for grease residue. If all is well then check the DV. But by all means check your boots first!

Why would the issue be the cv axle "boots" if the sound only occurs when coming off of hard acceleration / boost? I can get the sound to occur if I bring it up to high rev's and come off quickly while stopped.

[80sGuy]

Why would the issue be the cv axle "boots" if the sound only occurs when coming off of hard acceleration / boost? I can get the sound to occur if I bring it up to high rev's and come off quickly while stopped.

What makes me think so? Because our cars have a tendency to fuck with our heads when the simplest things go wrong, making one suspect problems that one most often tend to overlooked. Also, that's what mine did when I had a torn inner cv boot. It sounded choppy, fluttering, sort of like a helicopter under hard acceleration. Like I said it'll cost you NOTHING to check it, if not, then move on to the DV.

[SilentSquid]

What makes me think so? Because our cars have a tendency to fuck with our heads when the simplest things go wrong, making one suspect problems that one most often tend to overlooked. Also, that's what mine did when I had a torn inner cv boot. It sounded choppy, fluttering, sort of like a helicopter under hard acceleration. Like I said it'll cost you NOTHING to check it, if not, then move on to the DV.

Okay, thanks for the suggestion. I'll be sure to check it out when I'm under there.

[SilentSquid]

Replaced the DV last night and now I'm back to normal. Thanks to everyone for their help. Has anyone's rubber diaphragm come of in multiple pieces?

[Nollywood]

Sounds like a boost leak.

Either through a torn wastegate diaphragm, or a split boost hose / throttle body boot.

Any noticeable drop in performance?

[SilentSquid]

Sounds like a boost leak.

Either through a torn wastegate diaphragm, or a split boost hose / throttle body boot.

Any noticeable drop in performance?

Replacing the Diverter Valve stopped that sound and also gained back the performance I had lost - on it last night. Thanks.

[Ark88]

I have a similar situation when I let off the gas but the sound is much deeper and the flutter sounds like a f******* pigeon. It seems to occur only when in gear, and is more prominent at low speeds. I am uploading the best clip I can, if anyone has any advice please let me know. I looked and couldn't find any disconnected hoses, but that is finding a needle in a haystack. I am throwing a cell P0420. It is hard to hear but as the engine is winding down there is that pigeon sound. https://photos.app.goo.gl/eBLmHujSYxC6MDcX6

any help or insight would be amazing, losing my mind.

[EvolutionArmory]

Fix your cat. Work on what the car is telling you isn’t working right. It could be clogged and that back pressure can cause turbo flutter.

[Ark88]

That is solid advice. Last year I bought a USP 3" HFC. I mean how would it go about clearing a clogged cat. Could it be any part of the exhaust or more specifically the CAT as it states.

Other mods:
GFB DV+
CTS IC
Race Chip GTS ( not currently installed)

[EvolutionArmory]

That is solid advice. Last year I bought a USP 3" HFC. I mean how would it go about clearing a clogged cat. Could it be any part of the exhaust or more specifically the CAT as it states.

Other mods:
GFB DV+
CTS IC
Race Chip GTS ( not currently installed)

You don’t clean a bad cat. You replace a bad cat.

Sell that Racechip before you install it and buy a real tune.


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[Ark88]

I determined the fluttering sound was coming from the GFB DV+. I removed the GFB DV+ and put back my factory DV version J and all the fault codes that started piling up cleared. Now I am not sure if I should stick with the factory or get a replacement from GFB and reinstall that?

Unfortunately, I already installed the Race Chip, I just removed it to hep troubleshoot the problem.

[EvolutionArmory]

Run the stock DV and sell the Racechip.

You don’t need either of those things.




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