BOV problems

[truth211]

I am really getting tired of the small glitches in my car. I now have a ridiculous problem with the BOV. I have a Greddy rs BOV and it wont work. Here's what happens.

I boost up and let off the gas and it goes "Shhh Shhh Shhh Shhh Shhh Shhh Shhh Shhh" Sounds like butterflies. I traced the sound. It comes from where the air filter is. It sounds like when it needs to release the air instead of it blowing out the BOV it is making it's way backwards and going out turbo and back out the air fliter. I have loosened the tension on the BOV. I have removed the springs. I have cut new springs and tried to adjust it from there. I have tried 35 different tensions. Some with no result then the way it is now to it being so loose it wont hold boost and I run rich or can't build boost at all. The BOV has 2 nipples. The top one is connected to the Vacuum port on the intake itself and the lower one I just left alone. I have just tried everything I know of but still can not get the air out the BOV and not back through the turbo. I have removed the BOV and boosted with my hand over the outlet and there is a huge amount of air to blow my hand clean across the car. But why it's going backwards back through the turbo and not the BOV is beyond me.

So any help right now would be awesome because I am about to get rid of the car if I can not fix these stupid problems. Thanks.

[USMCgetsome]

COMPRESSOR SURGE! Look it up on youtube and you'll find similarities. This is due to a faulty blowoff valve that does not release(dump) the boost pressure properly. you then get the residual effect on the compressor side of the turbo due to it spinning backward. Which, destroys the turbo eventually.

Get your wastegate checked. If its an internal gate, get it cleaned up from rust. If you use a vacuum tester you will find that it will actuate at 8psi.

Also, more details on the turbo. Stock or aftermarket? Another thing to think of is to check your vacuum source to the blow off valve and waste gate.

for reference only and the proper term is compressor surge. ENJOY!http://jp.youtube.com/watch?v=...lated
Modified by KUILLIN_DRIFTER at 1:26 PM 10/13/2008

[zenki_myles]

do you mean the top vacume nipple is connected to the intake, or intake manifold.

cause that could be yoru problem. if its just conneceted to the intake there is no pressure difference when you let off throttle so it wont open. but if its connected to the manifold thats what allows it to open.

you probably meant the manifold but im jsut checkin

[truth211]

I am running a pretty simple set up. I wanted to sit around 250Hp so it's not wild or nothing. I have a stock T-25 (which keeps blowing the turbo to header gasket)grrrr. The top of the BOV is connected to the intake manifold just behind the throttle body. About 2". 370cc injectors, retuned ecu (crap job by redline performance...F-). Also a side note. My car boost creeps to 10.5 psi due to a 3" turbo down pipe. WG is connected to a nipple on the hot pipe and is turned all the way down. All my parts are new and have about 1100 miles on them if that. It's just racking my brain out why it's not working the way it should. If I disconnect the BOV, put my hand over it and have someone hit the gas to raise the boost; the second on letting off the gas there is a tremendous amount of pressure that shoots out. Now I have loosened the BOV enough to where is was easy to push the piston inside the BOV open but yet the damn thing will not work when I reconnect it. I am absolutely stupidfied on this. It litterally makes no sense to why it's not functioning as it's supposed to. Perhaps I will try using a different vacuum sorce such as the brake booster or what not. If that does not work I don't know what to do. Let me know if you have any idea's on this compressor surge. DO you think I should replace the BOV? It's a new Greddy r/s. They usually have a wonderful reputation so I would think it's not the BOV but I am open to the possibility.

[USMCgetsome]

you sure it's a greddy and not a freddy(fake greddy) Also, if it is a stock wastegate you should look into that. You sure as hell should not be seeing boost creep with a stock turbo and manifold. Also, use the vacuum source from the intake manifold to the waste gate. See how that works. From what i remember the rb25det has a 2 stage boost setup. Starts off high 10 and settles back down to 7-8psi.

btw i did see that the greddy type rs bov only has one vacuum source which is on top. You stated that yours has two?

http://cgi.ebay.com/ebaymotors...1wt_0

[Darius]

The vacuum line on the BOV should not be connected to the intake pipe. It should be connected to a vacuum port on the INTAKE MANIFOLD.

[truth211]

Let me clarify a few things up. I think I was not exact on my set up. I have a SS tubular header going into a T25 turbo. I have a 3" turbo down pipe going into a 3" down pipe; then continuing through a Apexi 3" exhaust system. I have read many forums about the boost creep. Using a 3" turbo down pipe does in fact create boost creep of 2.5 to 3 psi. Even with a stock turbo.

The vacuum line on the BOV should not be connected to the intake pipe. It should be connected to a vacuum port on the INTAKE MANIFOLD.

And I need to clarify about that as well. I am using an S14 upper intake manifold, an S13 lower intake manifold and all the emissions have been removed including Charcoal canister filter, EGR blocked off etc. The BOV upper vacuum sorce is connected to the lower intake manifold itself by the nipple right after the throttle body. It is connected to the intake manifold and not the cold pipe.

The BOV does have 2 nipples. One on top and a smaller diameter nipple below it at an angle. The upper one is for the vaccum and the lower is one for pressure from what I have been told. Some other cars like the EVO or the Subaru turbo'd cars that utilize both. Hope this helps. I have tried other vacuum sources and nothing seems to change.

The compressor surge still comes back through the turbo. It does not make any sense. Any other options or thoughts?