10-11-2006
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#1
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flips McGee
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BOV Flutter
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
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10-11-2006
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#2
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formerly ecoli
Join Date: Oct 2003
Location: On the dyno
Posts: 4,892
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Re: BOV Flutter
Is it a recirc style?
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10-11-2006
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#3
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Boost Junkie
Join Date: Apr 2005
Location: MN
Drives: I teleport
Posts: 586
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Re: BOV Flutter
Quote:
Originally Posted by scheides
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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?
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10-11-2006
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#4
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flips McGee
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Re: BOV Flutter
Yes, sorry it's recirculating bypass valve/BOV as seen in this pic (my car):
You should be able to view those vids in quicktime.
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10-11-2006
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#5
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Join Date: Mar 2005
Location: Blaine, MN
Drives: '91 Automagic
Posts: 13,908
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Re: BOV Flutter
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)
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10-11-2006
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#6
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Banned
Join Date: Dec 2003
Location: Boulder, CO
Drives: Conquest
Posts: 5,049
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Re: BOV Flutter
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.
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10-11-2006
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#7
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Join Date: Aug 2006
Location: Mpls
Posts: 290
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Re: BOV Flutter
Yea sounds like a defective spring.
__________________
Thaught
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10-11-2006
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#8
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AWD4G64
Join Date: Jun 2004
Location: Shoreview, MN
Posts: 2,286
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Re: BOV Flutter
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
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10-11-2006
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#9
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AWD4G64
Join Date: Jun 2004
Location: Shoreview, MN
Posts: 2,286
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Re: BOV Flutter
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.
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10-11-2006
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#10
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Re: BOV Flutter
My EVO does/did the same thing with the same BOV.
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10-11-2006
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#11
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Hold Alt & press F4...LoL
Join Date: May 2006
Location: Twin Cities
Posts: 344
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Re: BOV Flutter
How does it run with the bov disconnected and line pluged?
Has it been doing this from day one?
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10-12-2006
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#12
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flips McGee
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Re: BOV Flutter
In the pic I'm running a t-fitting. I'm currently running seperate runs from the intake manifold to the MBC and BOV. I've swapped springs and added washers/spacers (just like I said above) to no avail.
This has been happening since I installed the forge unit.
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10-12-2006
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#13
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R U DTF bro?
Join Date: Aug 2003
Location: Oak Point, TX
Drives: C8 Stingray Z51
Posts: 20,620
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Re: BOV Flutter
If this happens to both you and Nash it must be a common problem. What do the guys on the EVO board(s) say?
__________________
Quote:
Originally Posted by Murlo26
I agree with Kracka.
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10-12-2006
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#14
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flips McGee
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Re: BOV Flutter
Some people seem to have similar issues, but no one seems to have it as bad as I have...I'm going to do some boost leak tests (again) and possibly swap on the stock BOV this weekend just to see what will happen.
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10-12-2006
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#15
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R U DTF bro?
Join Date: Aug 2003
Location: Oak Point, TX
Drives: C8 Stingray Z51
Posts: 20,620
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Re: BOV Flutter
How about a different brand of BOV? If people have problems with them, why do people continue to use them?
Does the stock BOV leak like a 2G?
__________________
Quote:
Originally Posted by Murlo26
I agree with Kracka.
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10-12-2006
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#16
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flips McGee
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Re: BOV Flutter
I've heard nothing of this sillyness when I bought my forge. Nash says his car did it, but I can't imagine it is as bad as my car is. When driving at the limit, having partial throttle control is absolutly necessary, and it just isn't there on my car. The car falls on its face and I feel like I'm gonna die if I push the limit too much.
The stock BOV doesn't leak as bad as a 2G, but it is cheapo plastic, so I imagine it won't hold up to much abuse.
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10-12-2006
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#17
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Join Date: Jan 2004
Location: Ramsey, MN
Posts: 476
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Re: BOV Flutter
The IX's have a different BOV and so far people think it's better. Just another option to consider.
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10-26-2006
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#18
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flips McGee
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Re: BOV Flutter
Well, after swapping in every possible spring/shim combo, several boost leak tests, and a bunch of just driving, I gave up. I swapped in the stock DV/BOV and the fluttering is gone.
WTF should I do now? The stock DV is not going to hold up to what I have in store for it. New Forge? Go for something else? I'd go straight to a Tial, but I am still running the stock MAF. :P
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10-26-2006
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#19
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R U DTF bro?
Join Date: Aug 2003
Location: Oak Point, TX
Drives: C8 Stingray Z51
Posts: 20,620
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Re: BOV Flutter
Hks
__________________
Quote:
Originally Posted by Murlo26
I agree with Kracka.
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10-26-2006
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#20
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flips McGee
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Re: BOV Flutter
I'm gonna try getting a bung welded onto my LICP and see if that helps. I'm thinking the MBC and BOV seeing the same boost pressure (i.e. manifold pressure, after the TB) is causing some sort of weird loop: the BOV opening, dropping pressure in the system and making the MBC ball/spring close thus shutting the wastegate, which instantly causes boost to rise again. As this happens, the pressure in the IC piping is slightly higher than in the manifold, causing the BOV to open, dropping pressure in the IC piping and ......ah fuck it I'm gonna go buy a FORD
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