Flutter with stock 1G BOV

[Thebeast431]

I just recently replaced my old BOV with a new stock 1G BOV. Ever since I have been gettting flutter, only when I let off the gas while in boost range. I am not sure if it is coming from the filter or BOV, I tried to hear for it while a friend pressed the accelerator down and let off, but it didn't make the noise then. I have the 2 hoses hooked up just like stock. The only thing I did at the same time was a new K&N filter.
I have searched on the "flutter" topics, and half the responses say its bad, and the other half say the flutter won't harm anything. I don't want to take any chances, I just want to know how to fix it. I thought this would only happen to aftermarket BOV's?

Any help would be appreciated. Car is in Sig.

Thanks in advance,

Travis

 

[Kevin90GSX]

Couple questions.

What did you have prior to the new air filter?

If it was the stock Air Box and filter dont worry about it. When you get the cone air filter and remove the box the BOV is louder and more hearable.

Was it making this flutter noise at low boost levels? (8 lbs maybe 9lbs)

If you were at those levels and you let off and heard the BOV its simply doing its job and releasing air.


Hope that helps a little. Mine does the same thing.

 

[Thebeast431]

Everything I installed was already on there. I had the same intake, same K&N and same BOV as before. I just replaced the BOV and filter, figuring the BOV is 11 years old and the filter was pretty dirty.
It will make the flutter noise only when I let off the gas, at all boost levels. I have my MBC at 12psi right now, but it spikes to 14psi. As soon as I get into boost range, as low as 0 psi, and I let off I will hear the flutter. I heard my BOV before and it use to make the regular whoosh noise, but never fluttered. Since I put the same BOV in there, just brand new, I can only assume it will react the same.

Thanks,

Travis

 

[Kevin90GSX]

not necessarily man. As long as your holding boost and the car seems to be running fine I wouldnt sweat it.

I know my does both the whoosssiieeee and flutter.

Are you saying even at 12lbs when you let it off and your at full boost it doesnt whhooossiieeee but it only flutters? Id say put down your windows and listen again. If its still doing just the flutter exchange it. Also maybe your intake was so dirty you could hear the bov as well before. Or maybe I dunno where you live it was cold out and you didnt have the windows down and now you do and hear more. Coud be on of those.

 

[98TsiAWD]

Is it a flutter or a hihg-pitched kinda whistling sound?

 

[Thebeast431]

Thank for the info. As long as nothing is going to blow up, I can live with the fluttering.
As for the sound, when I let off the gas the whoosh sound is combined with the flutter. Starts with a whoosh, but almost simultaneously has the flutter added to it.
Just so I know, what is causing this flutter? Not enough air being released? Or possibly and obstruction, such as a piece of gasket covering the hole and getting flapped around in the intercooled air?
No high pitch sound, just the normal BOV sound combined with the flutter.

 

[Kevin90GSX]

Id definitely take the bov off and check make sure the gasket is ok and such and if everything looks good and its still bothering you exchange it.

 

[DSMgurlie]

Originally posted by 98TsiAWD
Is it a flutter or a hihg-pitched kinda whistling sound?

I'm having sort of the same problem. I just started noticing it a couple weeks ago. It kind of sounds like a tea pot whistle. I can only hear it when i'm going slow with the rpm's between about 1000 and 2000. Didn't know if it was some kind of leak or what.

 

[jott5555]

flutter like that stuff in thr robin williams movie????

 

[mitsuspeed]

Originally posted by jott5555
flutter like that stuff in thr robin williams movie????

thats flubber you tool. ya, mine does that to, dont worry about it

 

[Artago]

I have the same problem with a 1G Bov. I just installed a used 1G BOV on my 2G Talon and it flutters when I let off the gas. It does it under high and low boost. Is there anything I can do the 1G bov to stop it from fluttering? Thanks, Tom.

 

[2GeNTSi]

You know I just noticed this the other day when I got my car back, I had to use a 1g bov Paul (@ Newlogics) had lying around because my type-s was hitting the hood. I noticed that at low boost (0-2psi) it would flutter like the type-s would, it would have actually fooled me if I hadn't known the 1g was swapped in. Anyways a week or so later I swapped that one out with the 1g I was running before (it was cleaned up and painted rather than the dirty one I was using in the meantime) and I noticed the sound totally changed to how it always sounded (which was almost completely silent).

Now I noticed when I was swapping the dirty 1g w/ mine, that Paul put RTV under the gasket, so perhaps it was sealing up better than just the gasket by itself hence the difference in sound? I also noticed the cap on the temp bov was rotated at about 5 o'clock if the dump tube was facing directly at 6 (telling by the vacuum nipple). I don't know if this was a difference in design or the cap was simply rotated cause my vacuum nipple is parallel to the dump tube. I'm not sure what might've caused the change...

 

[Artago]

So what causes the 1G bov to flutter like that and what can I do to change it? I want the woosh sound a BOV is supposed to have. Could the line from the throttle body be causing it to flutter? Any help would be appreciated. Thanks, Tom.

 

[2GeNTSi]

No clue. It's a non-adjustable bov so I don't know what would cause it to make such a noise unless it wasn't sealing properly.

 

[Artago]

No clue. It's a non-adjustable bov so I don't know what would cause it to make such a noise unless it wasn't sealing properly.

Um ok. That's not a bad idea. Which seal(s) should I check and how? Thanks, Tom.

 

[2GeNTSi]

Well first take off the BOV and test it to see if it holds boost (handpump and a vacuum line). You'll know when it's starting to leak once the valve at the bottom starts to peak out a bit. I think the 1G can hold about 18psi? Don't quote me on that but I know it's around there, or at least it's supposed to be.

After that, put some RTV sealant around the flange under the gasket, bolt it back together and it should have a good seal.

Oh and here is a mod you can do to the 1G BOV:

http://www.thedodgegarage.com/turbo_bov_mod.html

 

[gsxtasy]

Flutter could be compressor surge. Not likley, but it is a possability. I had my vac line off once, so it couldnt open(or close) i forget. Mine would flutter when it was like that b/c of surge. So maybe the 'valve' in your bov isnt opening right...just thinkin out loud. btw mine whistles doesnt flutter though.

-aaron

 

[Artago]

Thanks for the link Matt, looks like a good mod to do the the BOV, and thanks for the info in testing my BOV seals. In response to Aaron, I don't think it's compressor surge, I have a stock setup, T-25 , and it's unlikely that it's surging because I'm running stock boost. However, I will look into it. Thanks for the info everyone, I'll get back to you once I figure it out and stop the flutter.

-Tom

 

[Mikelb]

The "flutter" you are describing is perfectly normal. Some BOVs will do it more than others, especially if the BOV was "crushed". The flutter comes from the BOV opening and closing really fast. This usually happens at low boost.

The BOV opens to let off an initial burst of pressure (pshhht) and closes, now the turbo is still spooled, and is spinning fast enough to still build pressure. The BOV has to open to let this pressure off, and with the low amount of boost, it will repeat this really fast and make a "flutter".

Mine does it, usually only when I'm not really boosting or letting off the gas and not hitting it again. The only thing is, you don't normally hear this, because when you're accelerating, you are usually shifting fast enough that the BOV doesn't have to keep opening, b/c you are accelerating and the BOV needs to remain closed.

I found a really good explanation of what's going on. I found this on some evo forums. There was lots more information, but I'm not going to post the link here. PM me if you'd like it. Below is the important stuff.

Valve Fluttering:

Valve fluttering is commonly thought to be an automatic indicator of compressor surging, and I would like to put that rumor to rest right now. This could not be further from the truth.

Compressor surging (caused by a bypass valve) implies that the bypass valve is not opening fully to allow the optimal amount of airflow required to keep the compressor wheel of the turbo spinning at an optimal speed.

Bypass valve fluttering will occur under various circumstances, so please consider under what situations you are experiencing fluttering before you presume that compressor surging is taking place, or more importantly, before it is assumed that a problem even exists.

Valve fluttering under wide open throttle or full boost throttle lift, again, typically means that a valve is tuned or adjusted to stiffly, and while this can lead to compressor surging and potential damage over an extended period of time, if the user fixes the issue quickly, no significant damage will occur. It would only be after prolonged use of a valve in an improperly tuned configuration that compressor surging MAY lead to damage or excessive wear on the turbocharger.

Valve fluttering under partial throttle or partial boost throttle lift, on the other hand, is a completely normal occurrence and IS NOT an indication of compressor surging by any measure.

Partial throttle or partial boost valve fluttering is solely an indication that the valve is directly responding to the inconsistent pressure differential on either side of the throttle plate (throttle body).

An internal combustion engine naturally creates a vacuum effect during the intake stroke of a given cylinder. When boost pressure is built from the turbocharger, it will reach a certain level inside the intercooler piping, but as it enters the intake manifold, it is almost instantly reduced by a given amount of vacuum created by the intake stroke of the engine, thus resulting in a marginally lesser amount of boost pressure inside the intake manifold compared to inside the intercooler piping.

Since the bypass valve sees references from both of these pressure sources, the sealing surface of the valve, be it a diaphragm or a piston, will respond to these differences in pressure, as minor or severe as they may be. This sealing surface response is what is creating the fluttering effect at partial throttle or partial boost throttle lift.

It may be more pronounced on some applications than others, and as mentioned above, the OEM Evo valves incorporates a feature to combat this issue, and while it will always be present to a small extent, it is not a problem for the vehicle in any way whatsoever.

So, as the article said, fluttering under full boost IS a bad sign. Fluttering under partial boost/no boost is NOT a problem.


Edit: I do realize that we pulled up a thread from 4 yr ago, I just figured it was ok, since we were adding to the original issue and found some sort of a resolution.

 

[stojo07]

1. Your spring on the BOV is probably tighter than your 11 year old BOV.
2. If you're not releasing alot of pressure, aka. letting off the throttle partially or not letting off of WOT, then there may not be enough pressure to open it fully making the fluttering noise.

As long as it's not doing it while you have the accelerator down then you're not having a compressor surge and it's not too big of a deal. Hope this helps

 

[richard33]

1. Your spring on the BOV is probably tighter than your 11 year old BOV.
2. If you're not releasing alot of pressure, aka. letting off the throttle partially or not letting off of WOT, then there may not be enough pressure to open it fully making the fluttering noise.

As long as it's not doing it while you have the accelerator down then you're not having a compressor surge and it's not too big of a deal. Hope this helps

look at the dates of the threads before you post on them. This thread was started in 2003. Figure it out.