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BOV Flutter?

SleepinGVR4

Well-known member
Joined
Feb 12, 2003
Messages
2,483
Location
Danville, Pennsylvania
What would cause my BOV to flutter at part throttle? It just started doing this. I guess it could be compressor surge idk. I can watch my boost gauge needle bounce around at the same time.

My car has a E316G with supporting mods. I should also mention I use a dodge missed 1st gen bov.
 

prove_it

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Joined
Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
If you blocked of the lower port feed to the underside of the diaphragm then the compressor will surge. It's from the valve not being able to open fast enough. I had the same issue when I modded mine. Low throttle compressor surge all the time.

This won't give you an exact answer, but it's what I did with mine.

Modded bov info/
 

G

Staff member
Joined
Feb 24, 2004
Messages
8,896
Location
zompton
Are you running speed density? Or recirc the bov?
 

gvr4ever

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Joined
Aug 6, 2002
Messages
6,190
Location
central Indiana
Spring inside the BOV could be getting stuck a little. On an adjustable BOV, if it does this, the spring is too tight.
 

prove_it

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Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
The flutter is from the valve not opening fast enough. I'd agree that the valve must be sticking. Try cleaning it up. If it still does it swap it out for another one. Also check your vacuum/boost line and see if it's leaking or kinked.
 

blacksheep

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May 1, 2002
Messages
15,485
Location
Urbandale, Iowa 50323
isn't there something about the bov vaccum line also not being tee'd too many times or too long of a run? I forget these things..
 

prove_it

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Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
Yes. You should NEVER tee into the BOV feed line. Also it's important to run the appropriate sized line. I still use the factory line since it's still in good shape. Too big and response is affected, also too small will have good response, but not enough volume to sufficiently open the valve instantly. Also the length will create the same issues, too long and response is hindered, but there is not too short. Shorter is better. Anything under 2 feet should be ok I think as long as the diameter is right.
 

James

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Joined
Apr 7, 2012
Messages
1,322
Location
Port richey Florida
Pretty much. I mean every tee or every inch of line makes the BOV work that much harder to open. I don't know if you've ever tried to push one open with your fingers but its pretty stiff.
 

blacksheep

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Joined
May 1, 2002
Messages
15,485
Location
Urbandale, Iowa 50323
In my modding days, I went thru so many damn BOV's for flutter, surge etc. I will say the HKS BOV re-circulated helped cure most of the issues I had. I believe its a pull-type (opens based on vacuum rather than boost - more boost and more it stays shut, I think). I think the only other one that makes as much sense is the Synchronic which is based on HKS design. The HKS will also make a flutter-like noise since it has a soft spring and a heavy spring or something. I know that the HKS does require a good vaccum source.

Also, I remember someone saying bigger cams cause less vacuum and this effects BOV's or something?

I am not super technical - so, pardon me!
 

prove_it

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Jul 3, 2008
Messages
4,201
Location
Sioux Falls, SD
Yes, cams will affect vacuum which changes the valves operation. When you shift though the engine will see a deep vacuum as it's revving higher and the plate is shut, so between shifts the valve will act normal. At idle it won't open as far for recirculation.
 

Try a 1jz with a 72mm turbo you want to talk about compresser surge.And yes bigger cams do effect vacuum
 
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