BOV Flutter

[scheides]

Since I put a Forge BOV on my Evo I've been having this problem. The BOV flutters under any sort of PARTIAL throttle. The worst is on the freeway. If I give the car partial throttle to accellerate through traffic a bit, and the car builds a small amount of boost (1-5psi or so), the car bucks back and forth, building boost and blowing it off/bypassing air continuously.

The other thing that happens is under partial throttle, higher boost, higher rpms (4500+). The BOV seems to flutter. No bucking, just fluttering.

The worst is when both of these are combined (little of each case above going on).

I also have a hallman MBC hooked up. Both the MBC and Forge are fed manifold pressure, but from seperate feed lines.

Anyone have any advice? Here's some cell-phone vids of these conditions:

http://www.scheides.com/misc/MOV00012.3gp
http://www.scheides.com/misc/MOV00016.3gp

[Shane@DBPerformance]

Is it a recirc style?

[clean2g]

http://www.scheides.com/misc/MOV00012.3gp
http://www.scheides.com/misc/MOV00016.3gp

How do I view these bad boys? Not familiar with the Forge BOV but for the flutter issue, isn't there a way to adjust the hardness/softness?

[scheides]

Yes, sorry it's recirculating bypass valve/BOV as seen in this pic (my car):

http://www.scheides.com/albums/evo8/DSC00607.sized.jpg

You should be able to view those vids in quicktime.

[turbotalon1g]

I have a Forge and haven't had any similar issues, but def. check what colored spring you should be running for the amount of boost you are running.
(They change hardness of BOV)

[FattyBoomBatty]

Perhaps the vacuum line is hooked up to the wrong port on the TB or manifold? the only other thing is the spring strength, if you need a temporary fix, take the sping out and stretch it out so it's longer. or toss some washers in there like a TurboXS.

[HKSenilyks]

Yea sounds like a defective spring.

[blageo23]

I dont know what the inside to this BOV looks like but I read that for the Greddy BOV there are 2 springs and on EVOs you are sapose to remove one of them to not have this happen. Im gonna try and look for where I read that.

Heres the website...
http://www.evomoto.com/tech_info.php?tPath=1&tech_id=7

[blageo23]

Looking at the pic it looks like you have a T fitting off the BOV line. Did you change that or is it still like that. If its still like that try giving it its own source.

[Nash]

My EVO does/did the same thing with the same BOV.