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)

[norcal_drifter]

try a different bov or crush it???

[Skippysnax]

yes the arrow is supposed to point in the direction of the airflow.

[topekagsx]

take off the blow and take a look at it to see if anything is hanging up/sticking

[nek]

I have taken a look at the bov and it looks fine. I dont think its the bov though because it worked fine before my newest install. And I dont think its a premature opening problem because Im currently not boosting to much.
Is it possible that maybe the bov isnt seeing enough vacuum from the intake mani? Maybe the mani is drawing air from a different source and its causing issues.
Thanks for the input

[Jerkychew]

Don't you have to change a setting in DSMlink for the GMmas?

[drunkin_idiot]

Try an adjustable Bov like the Greddy.

[nek]

Yes, I did have to change the ecmlink setting to use 3in gm maf.
The idea is not to find a bov that works, Im pretty sure mine works fine.. Its to find what is wrong and whats causing my issue Oo. The 1g bov has been proven to work many times without issues on psi much higher then what I am running.
I would ask if its possible that the bov is to far away from the tb right now but Ive seen bovs placed right after the fmic so I dont think thats the issue either. Blah...

[rx7ttlm]

Originally Posted by nek

Yes, I did have to change the ecmlink setting to use 3in gm maf.
The idea is not to find a bov that works, Im pretty sure mine works fine.. Its to find what is wrong and whats causing my issue Oo. The 1g bov has been proven to work many times without issues on psi much higher then what I am running.
I would ask if its possible that the bov is to far away from the tb right now but Ive seen bovs placed right after the fmic so I dont think thats the issue either. Blah...

get your hands on a vacuum pump, and measure what your idle vacuum is. Whatever the value is in inches of hg, subtract 3-5 and that is where your bov should be opening. So if your idle is 20 in/hg, your bov should START to open between 15-17in/hg. It should also not leak during a boost leak test.

cheers

[TenSecondSTi]

Originally Posted by rx7ttlm

get your hands on a vacuum pump, and measure what your idle vacuum is. Whatever the value is in inches of hg, subtract 3-5 and that is where your bov should be opening. So if your idle is 20 in/hg, your bov should START to open between 15-17in/hg. It should also not leak during a boost leak test.

cheers

I boost leak tested and mine was opening a little at 20psi so i crushed it down a little.

Maybe you have a boost leak? Or your throttle plate isn't fully closing try adjusting the BIS back out some. Or the BOV could be crushed to much.

[nek]

Originally Posted by TenSecondSTi

I boost leak tested and mine was opening a little at 20psi so i crushed it down a little.

Maybe you have a boost leak? Or your throttle plate isn't fully closing try adjusting the BIS back out some. Or the BOV could be crushed to much.

Hm, didnt think about the tb not closing all the way. Ill try to pull the biss out some tomorrow. My bov isnt crushed. I have gd mod though.

More opinions on what it might be would be awesome. I gotta have everything settled for this weeks dsm meet

[TenSecondSTi]

Originally Posted by nek

Hm, didnt think about the tb not closing all the way. Ill try to pull the biss out some tomorrow. My bov isnt crushed. I have gd mod though.

More opinions on what it might be would be awesome. I gotta have everything settled for this weeks dsm meet

Is that the mod where you block off the original vaccum port and run it out the side to the manifold?

If so i think that may cause a flutter. I know doing this mod on subaru BPV's gave it a flutter sound because the valve was more active.

[nek]

Originally Posted by TenSecondSTi

Is that the mod where you block off the original vaccum port and run it out the side to the manifold?

If so i think that may cause a flutter. I know doing this mod on subaru BPV's gave it a flutter sound because the valve was more active.

Sorry for not responding sooner. I had bov flutter before I did this mod. The gd mod doesnt effect the vacuum port. It adds a side exit for trapped air to get out on top of the bov. Basically all it does is allow me to hold more boost.

I found out my 1g bov leaks air at idle. I read online this could be because my IM has very strong vacuum. My boost gauge reads -20 so Im thinking this might be causing the problem but Im not sure what to do to fix it.

[EclipticalGS]

a side exit for what trapped air?? air in the IC piping or air from the vacuum hose. If its air from the vacuum hose, thats not good.

Do a BLT.

[nek]

Research Garage door mod. As I said before, it happened before I did the mod. I attempted the mod to try to fix it.

[Tooltrt87]

Digin up somethin old it seams.
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.
Im wondering if thos was solved. I have an fp green and a tial q.
Lokking for a solution its hard to set afr with this flutter issue.

[Dert]

What spring is in your tial q? Your vacuum may be different and your spring may be too tight for your vacuum.

[NHerron]

What Dert/Gary said.

Record your engine vacuum via the intake manifold with a vacuum gauge like a MityVac and compare to this chart:
http://www.tialmedia.com/documents/BOVspc.png

[Tooltrt87]

My vacuum is at -10 i have the black spring rated for between -8/-11.
should i just try an even lower spring? would there be a draw back to having a spring that is to weak?

[NHerron]

If you're only at 10inHg, you either have a boost/vacuum leak or a worn engine. How long does it take to get to full boost?

Actually I see you have cams, so that could effect the reading. Have you done a BLT?

[Tooltrt87]

Ill post a log tomorrow it will give you full detail on your questions.
I have done many boost leak tests the results are perfect i have no leaks.
Engine compression is 150 in all 4 when it is fully
Warmed up.
I was told maybe its surge. 28 psi fp green stock block and head. Possible??

[Dert]

Stock head??? Your prof says you have kelford cams...to my understanding with aftermarket cams your inhg gets lower the higher the lope of the cams. A stock head with stock cams will idle around -19inhg, I'm thinking that your 264 kelfords should probably be around -15 ish as a lot of 272's idle a little lower than that. As stated earlier, you probably have a vac leak somewhere.

[Tooltrt87]

When you say 272 idle with less vacuum than my 264 what brand do u speak of? Kelfords or just any?

[ramsack]

Flutter means it's working correctly.

[NHerron]

Originally Posted by ramsack

Flutter means it's working correctly.

Really.

Care to expound on that any further?

[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.