Best way to adjust GFB BOV

It does not seem to matter whether I blow out full atmosphere or fully recirc. It does not backfire or have rough idle. There is also the center adjustment that is responsible for how easy the air is released and how long the valve stays open for.

 

If I set for 50% Blow off to atmosphere w/ no back fire will that still be okay? I know there is a second that the MAF does not get the air it accounts for causing a rich condition. Can it cause other issues other than backfire?

 

I simply installed the new BOV and made no adjustments. I sure adjustments need to be made but what are they and what is the best place to start from?

 

Any advice would be great.

 

 

Thank you,

 

 

Scott

if youre stock turbo you should be fine right out of the box. i had to mess with my spring a little, and i keep mine at about 40 % atmosphere 60 % recirc. i was always adjusting mine trying to get rid of the wimpy fart sound before the "pshhh" but it never went away until i went to a FMIC

You should probably state if you have the GT hybrid or Respons (sp?)

With the GFB if you are fully open it is actually 50/50 not 100% atmosphere. Look at the valve with it out of the car you will notice both ports are open.

To late now it is installed and I am not taking it off to confirm According to the instruction sheet that is not the case in regards to fully open open only being 50% but maybe you are on to something.

Also I thought this BOV would put out a high pitched whistle and whoooossshhh sound. This is just a sloppy sounding whooosshhh. Is that a different brand that sounds like this? Not a big deal though. I am almost certain I was leaking under boost as the boost it much more constant and power is up. I do not have a boost gauge just yet believe it or not.

Sorry this is the GFB Respons TMS, T9001. Also I have the standard trumpet so whooossshhh is all I get unless I buy the long trumpet.

Still need to understand how I should adjust the center spring for pressure control and length of time it releases.

If the screw is too loose, there won't be enough pressure on the spring, and ergo the piston will move too easily and may move or remain open during idle. You do not want that.

 

If it's too tight, then you'll hear flutter from compressor surge during vent conditions because the piston doesn't open quickly or wide enough.

 

The way I did it was I tightened it down a turn and made sure the idle was good and it wasn't venting. You can actually see the piston through the VTA port. If it's closed, tighten the spring down another 1/2 to 1 turn and drive the car and see if it vents okay under boost (WOT and partial). If it's okay, tighten it down a bit more and check again. Repeat until you just start to hear the flutter, then back the spring off a half turn or so and you should be fine.

 

edit: Sorry, just reread my post and want to clarify: look through the VTA port. If the piston is moving at idle or open, tighten it down gradually until it closes, and then tighten it just another half a turn more. THEN drive off and see if it vents properly. No compressor surge means you can tighten it down a tiny bit more. When you get just the tiniest bit of surge, back the spring off a bit.

Cool thanks that makes total sense.

 

Scott

edited my post a bit to clarify.

http://legacygt.com/forums/showthread.php/technical-info-bov-bpv-set-up-and-operation-150687.html

^ Thank you sir.

 

Funny thing, OP is a customer of mine, but did not buy the BOV from me. It was accidentally shipped from another vendor to my shop and I forwarded it to the OP.

 

Scott, it cost $10 and change to ship it to you. lol.

Jw would a bov fr a08+ wrx work on our cars?

yes, same TMIC/flange

Hey Mike,

 

I did not even thing about that, I will get you back on that. Thanks for the quick ship.

 

Scott

No problem. Have fun with the GFB. My favorite BOV/BPV for a Subie.

the screw just adjusts for compressor surge or early opening for pressure differential from compressor housing/end of IC

Already covered. But thanks and welcome to the forum.

Noticed something, if I have the BOV opened at all the car idles terribly in the morning, backfires now in between shifts, and stutters more than normal. General lower drivibility even when its warmed up but sounds mean on hard shifts.

 

So if it idles poorly while warming up tells me the BOV is releasing a slight amount of air to atmosphere that the MAF should be seeing during warm up. How can this be? I thought the BOV was closed unless boost is release between shifts? If I close the BOV circ valve the poor idle goes away. the surge spring does not make any diff only noticed change during shifts.

 

Scott

Did you adjust it the way I told you to? Turn the knob so that you're full VTA and sit there with your car idling. Look at the piston through the VTA opening. If it's opening at all during idle, you didn't do it right.

Should not be open at idle. If venting to atmos and it is open at idle, you have problems.

 

On my old (pre-Response) GFB that I run on the 5EAT, I have had to replace the spring twice in the last 4 years because it got weakened and would lift at idle. Replaced it just a few months ago.

I spun the center adjuster until there was no backfire and no weird idle especially in the the morning. Seems to be just fine now it is about 1cm below the surface. I am still blowing off to atmosphere about 25% so it does not sound to ridic opposed to 50%. I need to get the other long trumpet that sounds more mechanical or metal whistle opposed to that sloppy ass whooossshhhhhh it has now. Thanks everybody and here I thought Mike just jacked up my engine... Just bustin your balls Mike glad you did the work than anyone else by far. I will tell you I need to move e85 though. I will contact you soon.

I have very mild actuator flutter, more normal than anything else at low speeds when lifting.

When the BOV/BPV is set right for full boost you will get a light flutter at low boost when letting off. This is normal.

 

Rarely will a Subaru allow you to vent more than 40% without a slight pop on shift. Some I can get to 50% (like 5EAT's, lol). 40% seems to be the normal maximum amount of vent without pop.

 

I am here if you need anything. If there is/was/were an issue with motor all you have to do is bring it in.

Mine started popping at even lower levels, doh! But I think I'm getting tired of the pssh noises already so I closed it completely. The car almost seems eerily quiet now. I think my BOV is actually quieter than the stock one.

Pssstt, stay recirc, get a decent 1 from FORGE or trusted company.

I usually crush the stocker a little (non Legacy platform) to hold solid boost levels up to 25 psi, obviously not on stock set up and never had any issues.

Your stockers should hold solid up to 18-19 psi.

Ive ran a lot of stock BOVs up to 19 psi on various platforms.

 

Ive messed with my own Variable BOV, did not like the rich spots on shift change or the noise, it came on a car I purchased and was swiftly exchanged for a stocker I had on the shelf, it ran so much better instantly.

 

iNVAR - I'm not stalking you