BOV Fluttering

[pitbullowner_2]

I just bought a greddy type s bov and it sounds to me that its fluttering i know i adjust the screw up top but i dont know do i soften it or tighten it... also i did not cap the lower nipple or use it good or bad idea could that be the problem? also i smell a weird almost like a burning smell not quite for sure....someone please help!

 

[97GSTJake]

this is really weird, i posted a thread today about the same thing! my greddy type s was installed yesterday, lower nipple left alone, left open ......and i smell some weird burning type smell whenever the car is stopped. my bov is fluttering as well, i dont know how much to harden or soften it.....someone please help us

 

[kottyking]

screw down w/ an allen key to tighten in. Then tigten the bolt. The bov should sound crisp when set right. If its fluttering its set to soft, which usually causes surge to the turbo. So you might wanna tighten it.

 

[97GSTJake]

so is the smell the turbo being too soft and getting fried?????

 

[pitbullowner_2]

if i put my hand on it, it feels like its surging so just tighten it till i dont fell it anymore? sorry for the dumb ?'s i'm new to dsms but love them to much to ever leave

 

[pitbullowner_2]

also how much should i turn it each time i dont know how touchy they are? also i just put in a mbc and have not set the boost yet its as low as it can go

 

[kottyking]

so is the smell the turbo being too soft and getting fried?????

I would hope not. It doesn't smell. It just flutters like a chicken. Its pushing the air back to the compressor wheel, and over time damages it. Thats why you set it harder.

 

[cHz]

Well, when I got my headers put on, for the first 2 days or so, there was a pretty bad smell coming off and I talked to the garage that put them on, he said that it's just cause they're new and it will go away soon, so maybe that same thing is happening with your BOV, but that's just a guess .

 

[97GSTJake]

i actually bought the bov used from a friend of mine, in great working shape though

 

[kottyking]

if i put my hand on it, it feels like its surging so just tighten it till i dont fell it anymore? sorry for the dumb ?'s i'm new to dsms but love them to much to ever leave

Hey there arn't any dumb questions thats how you learn. We were all noobies once. You tighten the main bolt sticking out w/ the nut on it. You find the appropriate size allen key for the top of the bolt and tighten. THen get in ## car rev it and see if it is a high pitched whistle when it blows. Once you get the high pitched whistle your golden and its set. If you keep getting the fluttering sound, its usually compressor surge. Also, be careful tightening down the bolt as they have been known to strip, its happened to me before. Good luck.

 

[pitbullowner_2]

cool.. i didnt think about that...ahout the touchyness of the bov start turning a half a turn or what?

 

[kottyking]

yea, maybe more towards a full turn.

 

[hereitcomes]

The fluttering (turkey) sound is called "compression surge". You will find alot of information in the forums- check out the search area.

The bottom nipple can be left open. Its an extra release valve for the BOV and does not need to be tapped.

To adjust the BOV - turning the screw to the right will tighten the spring and loosening it will need to be turned to the left. This is the spring that controls how much boost requires the BOV to open. The harder it is set the more boost will require the spring to open, and the softer the spring is set the less boost will make the spring blow off. You have to find the right setting for how much boost you are running and what your set-up is.

 

[pitbullowner_2]

so at an idle i cant tune the bov cause the screw up top is even with the lock nut and at an idle it sounded like it was fluttering

 

[97GSTJake]

ok guys i just took the car out: I would run it down the road and let it blow off, if it was flutter i would stop on the side of the road and turn one full turn to loosen.....the looser it got, the less i heard the flutter before the whislte.....i probably did this about 10 stops haha, each stop was a FULL turn.....i gave up on it for tonight but right now it is at the point to where i can rev it to about 4k rpm and hear it whistle..... i can still just A LITTLE bit of flutter before the whistle when blowing off....it might need just one more full loose turn.....

 

[pitbullowner_2]

awesome idea i didnt think about that i just kept going back to my house, and one of the people said to tighten it but if you loosened it and it worked i'm gonna do the same thing thanx man

 

[97GSTJake]

yea people have told me to tighten mine as well , but when i tighten it, the more i tighten, the more FLUTTER i get, less whistle..... i probably have a good 6 or 7 threads showing on the top around the wing nut (about 1/2 of an inch above wing nut)

 

[desertspyder]

If you tighten it down it takes more pressure to release. The pressure returning to the turbo causes the surge so you definately need to loosen it in order to stop the pressure returning to your turbo and release with less pressure in your pipes. Hope this helps.

 

[zippyshoe]

If you tighten it down it takes more pressure to release. The pressure returning to the turbo causes the surge so you definately need to loosen it in order to stop the pressure returning to your turbo and release with less pressure in your pipes. Hope this helps.

Exactly. If you experience "flutter" which is actually the sound of compressor surge, then you must adjust your BOV to a SOFTER setting. In some set-ups, even with the Type S set to fully soft, you may still get compressor surge at lower boost levels. In this case, to eliminate it completely, you may need to perform the single-spring mod to your BOV as described here: http://www.evomoto.com/tech_info.php?tPath=1&tech_id=7. Hope this is helpful.

 

[93WhiteLaser]

I'm not sure if this is my first post or not, but I've had my dsm for over 8 years now, I've used the forum countless times, so thanks to all those who has replied with answers. I just want to post my compressor surge fix to any one who's looking.

Compressor surge could be from lack of vacuum to the bov when you release the gas pedal. I have a blitz bov and stock air sensor. Always vented to the atmosphere with no issues. However after I did a larson hose kit upgrade from RRE. my bov didn't blow anymore. I hear surges at any psi, the higher the psi the worse the surging. I search all over the forum and every one gives advice for the spring tension. Yes, too hard of a tension can make it flutter but if you don't have enough of a vaccum pulling on the bov then no matter what the spring tension is, it'll probably still not vent very well. I fixed this issue by removing the 'T' fitting from the bov to the turbo outlet pipe and the wastegate. I plugged the port on the turbo outlet so now the mbc is hooked to the wastegate and then 'T' with the bov port and intake manifold port in the center of the manifold. Therefore, when I let go of the gas now. It's getting full vacuum from the intake manifold instead of some vacuum from there and other side sucking some air from the turbo outlet.

I never had a problem before the new hoses, but I think because the new hoses has less flex and more volume in them, as a result, sucking more air from the turbo outlet killing my vacuum strength on helping the bov vent.

Hope this helps you who are searching for bov fluttering fix.
(I'm gonna add some key words here to help those who are looking for this issue to find this search easier) (compressor surge, blitz bov fluttering, bov not venting, bov flutter)

-Alvin
93 laser rs(nt auto abs- turbo manual no abs)
P.S. Props again to all those who contribute to this forum and give good advice

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[ericbev]

How do I adjust my BOV correctly?

The "harder" the setting (the deeper the adjustment screw. I assume its the same as the type-s), the less prone the valve will be to being blown open and the greater the change in pressure needed to open it. Set too soft, the valve could possibly be blown open under high boost. Set too hard, the valve may flutter or not open at all. Any fluttering from too hard of a setting will be most noticeable during light throttle changes since there is only a small change in pressure on either side of the valve. The more you let off the gas and/or the more quickly you let off, the greater/sharper the change in pressure and the increased ability for the valve to open flutter-free. In short, for the very least potential valve flutter, adjust the spring as light as possible without it being blown open for your setup and boost level. The fluttering sound you will hear is also known as compressor surge and is bad news. So basically, loosen it up enough that you dont hear fluttering at very low throttle releases, but make sure its hard enough that it doesnt start blowing off boost. It shouldnt be hard to find this "neutral" spot. The fulttering is very noticeable and so is the valve blowing off boost. Go on a backroad where its you and the road (nice and quiet), carry the allen wrench and box wrench with you, and play with it till you are satisfied

What is compressor surge?

Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. It is commonly described as a chuffing or fluttering sound depending on the severity. You will know it when you hear it.

What happens If I still get surge at low throttle releases with little to no adjustment left and compromised response?

The "single spring mod" allows for a lower seat pressure and gives you a little more adjustment room if you are running out. Although, it can raise your boost threshold slightly.

You could also utilize the lower chamber of the valve. Compressor surge at light throttle lifts can be further reduced by connecting the lower fitting to a pressure source. Typically a fitting is added to an I/C pipe between the turbo and the BOV to use the trapped pressure to help push open the valve during these low pressure change conditions. Although slightly more involved, this method allows for crisp on/off transient response inbetween gears without the reoccurrence of surge.

I hope that helps.