Bov flutter. Help fix?

[nek]

SO my 1g bov started to flutter after I installed a gm maf on the upper ic right before the tb.. I really dont know why. At first I thought it was because my vacuum hose was to short and maybe it was kinking so I replaced it with another smaller ID one that was longer. Didnt fix it, then I thought the small ID on the new hose might be the problem so I put back on the old one and turned the bov so the hose has no flow issues. Still doesnt work.
I really dont like the fact that I can hear what sounds like my newly rebuilt turbo scratching the turbo housing after the flutter. I have a direct line to the intake manifold and it didnt do it before the gm maf install with ecmlink and new ecu.
Recommendations on how to fix it? Thanks!
And a random addition, the gmmaf is supposed to point its arrow towards the tb right (with airflow)

 

[ramsack]

The BOV opens, pressure drops, as pressure in the charge pipe nears zero the BOV will close, pressure will build again because the turbo is still spinning, the BOV opens, repeat over and over. It's normal and doesn't mean anything is dysfunctional. It is also not surge. It's a simple oscillator.

 

[NHerron]

Then the spring is too tight. It should not flutter with low boost applications.

 

[ramsack]

A spring in a BOV is not made to keep it closed under boost. You're thinking of these POS aftermarket BOVs. They are there to return it to a closed position. They are not there to hold it shut. What holds them shut is pressure via the hose that runs to the intake manifold. The area on the diaphragm is larger than the area of the piston that seals off the outside from the charge pipe. More area at equal pressure means more force. Flutter is normal and doesn't hurt anything. If you shift slow enough to have to worry about that flutter slowing down the turbo, then you have problems.

 

[NHerron]

I never said anything about how the BOV holds boost. I'm talking about why too strong of a spring causes flutter.

The springs main purpose is to keep the BOV closed at idle/high deceleration, this is where flutter comes in. Too tight of a spring (one rated at higher than current IM VAC) and low enough boost pressure in the charge pipes keeps the BOV from staying open long enough to fully release the air, thus results in mild flutter. The spring should be picked according to the highest IM vacuum recorded, IE high RPM's/throttle closed such as when just letting off the accelerator.

The spring plays a part in holding boost, albeit a small role. If there was no spring, the valve would float. Although, I agree, equalibrium on each side of the BOV mostly keeps it shut.

*Okay I think maybe I can agree on the area vs. pressure thing. It makes sense but I have a bit more reading to do for my own curiosity.
http://www.turbov6camaro.com/bov.htm

 

[Tooltrt87]

Flutter means its working? Please explain.

 

[ramsack]

I've already explained. I should have said "flutter doesn't mean it's broken."

 

[Tooltrt87]

i have completed another boost leak test and........the boost source off the turbine housing was leaking a bit, the spaces between the gm maf were leaking and last but not least my brand new tial!!!! top hat section where ya change the spring.
absolutely ridiculous. it was only a little bit but any amount is obviously uneven pressure and will not work!!
my car now holds its boost pressure and my hz for my maf are better.
car has zero knock at 30 psi with 11 degrees of peak timing how am i doin?
As for my vacuum issue. I put new seals in my throttle body last year and im not certain but when ever i flick the throttle the idle changes it must be sticking a bit gonna disassemble in the future and see what i find. unless someone has a 1g throttle body that dosnt leak that they would sell

 

[NHerron]

There's a few article on how to rebuild your TB and snowborder714 sells a nice rebuild kit

TB Rebuild
TB Rebuild
http://www.dsmtuners.com/forums/new...many-you-have-rebuilt-your-throttle-body.html
Throttle Body Rebuild Kit - Classifieds

 

[Tooltrt87]

Thats the site i used last year i must of done something wrong is all i can figure. well......i obviously did something wrong haha

 

[NHerron]

Well maybe it's just an adjustment needed and not a rebuild if during your BLT the seals weren't leaking?

 

[jmdst28]

Mine does a similar thing when building low boost on my evo316g. but when i accelerate quickly and let off the gas it seems normal. I have my heavy spring in my Greddy rz bov. Max boost is 22 psi. Should i go to the lighter spring

 

[NHerron]

Boost doesn't matter for picking the spring. It's based on IM vacuum.

The RZ is adjutable, have you loosened it up to get it away from fluttering? Just idle the car, look inside the BOV while loosening the threaded rod. Once the valve starts to open up, tighten the threaded rod until the valve is closed again and then give it one more full turn past closed

 

[jmdst28]

I have only tried making it harder and softer. But it still seems to flutter no matter what

When you say look inside the bov should i take the recirulating tude off and look inside?

 

[NHerron]

Yeah take the tube off and look inside.

So if you loosen it all the way it still doesn't make a difference? Have you done a BLT and at what PSI?

 

[Tooltrt87]

yes i have no TB leaks

 

[NHerron]

I am having this same issue after my gm maf install my bov flutters. This occurs with high engine load. Low revs in let say third gear bost build up gets to max boost 28psi flutters for about 100 rpm then settles and its fine

This is saying you punch it WOT, let pressure to build up to 28psi, then let off the throttle and it flutters right?

I thought your issues cleared up according to post 32?

 

[Tooltrt87]

My issues are solved yes. My bov flutterd during a a wot pull. My bov is just one good "swoosh" when i let off. I didnt have a flutter at throttle release or let off if you will.

 

[NHerron]

OHHH! Okay reading fail on my part for your original post, sorry about that. We could have figured this out a while ago.

This is a different problem, which just so happens to be the same sound as flutter. But has nothing to do with the correct spring inside.

When people mention flutter it usually means the BOV isn't releasing fully as it's supposed to when letting off the accelerator with boost still in the charge pipes.

Instead in your case, the top portion of valve started leaking boost bad enough above a certain threshhold, causing a fluttering condition, but worked fine releasing the air, since the leak wasn't big enough until "x" amount of boost.

It looks like a few have had this problem with the same TiAL..

Glad you got it figured out anyhow

 

[Tooltrt87]

It was a simple fix. I just got a zip tie and used it to dab rtv on the outside of the diapram to the outer edge where the top hat of the valve bolts down on the bottom half.
Either way this is ridiculous! After this slight error the valve will work great!!! But cmon? Really? Cant guarantee a perfect product after 239 bucks?