# Forge Splitter BOV/DV Issue



## 20s2VW (Oct 25, 2007)

I have a forge splitter BOV/DV on my car, and it seems to be staying open at idle when I looked under the hood. I can usually see the piston covering the release hole, but now it just stays open. Any ideas? 
It doesn't hurt the cars performance, it just is .....weird.


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## 20s2VW (Oct 25, 2007)

*Re: Forge Splitter BOV/DV Issue (20s2VW)*

bump


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## WolfPac (Oct 5, 2001)

*Re: Forge Splitter BOV/DV Issue (20s2VW)*

I have the same valve. The brass piston stay open during idle. When you gas it, it shuts close and opens when you release the gas. 
I'm thinking of switching back to the stock 710n because my car seemed more responsive with it then the Forge Splitter.
Also I don't think it's good for the engine if the valve is open to the atmosphere during vacuum. Something could possibly get sucked in there during idle.


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## 20s2VW (Oct 25, 2007)

*Re: Forge Splitter BOV/DV Issue (WolfPac)*

Ya, it's weird, also, which way tightens lol? Clockwise or counter clockwise?


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## cincyTT (May 11, 2006)

*Re: Forge Splitter BOV/DV Issue (20s2VW)*

you guys dont have the large hole venting? The small hole is raised up and cant leak at idle. Also, you do have it installed in reverse to stock orentation?


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## Mspeedy3 (Jun 20, 2009)

I have a Splitter installed, and it doesnt stay open at idle!!!!
The minimum set spring pressure alone should keep it closed... it should only open when theres vacuum on top (little vac hose from mani side of throttle plate) and excessive pressure on the bottom (larger hose from between turbo and throttle plate)...
please tell me its installed so the side (discharge) outlet goes directly into the intake tract, and the bottom (inlet) is connected to the 20mm hose from behind the engine... the atmospheric outlet (that you can see the little hole thru the horn) should be pointing somewhat toward the head, if you have the engine plastic cover removed.


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## Mspeedy3 (Jun 20, 2009)

*Re: Forge Splitter BOV/DV Issue (20s2VW)*


_Quote, originally posted by *20s2VW* »_Ya, it's weird, also, which way tightens lol? Clockwise or counter clockwise?

oh yeah, looking down at the top of the valve (little nipple being the top), clockwise tightens the spring pressure; 8 clicks per revolution, about 7 revolutions... mine is now at about 12 clicks (1.5 turns) from all the way counter-clockwise, and holds 15psi but still blows off when I let off... and response is definitely better than the stock Bosch piece!


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## Green 1.8T (May 16, 2008)

Mine is also closed at idle, it should not be open. Im running at 15-16psi and i had mine turned 24 clicks clock wise and its working 100%


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## 20s2VW (Oct 25, 2007)

*Re: (Green 1.8T)*

It's installed in the right position, I have my car chipped (GIAC) and am running about 19-20psi and my valve is turned about 10 clicks....so I dont know what's going on


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## WolfPac (Oct 5, 2001)

*Re: (20s2VW)*

I just checked on this today again. When I first start the car it's closed, but after it idles down to ~800rpm then it opens a bit. A part of the brass piston is a little visible thru the small opening. The DV is connected directly to the intake manifold, N249 bypassed and I have it cranked about 25 clicks clockwise.
When I drive it around I don't hear the valve leak until I let off the gas, so I know it's holding boost properly (boosting around 18psi). It's just kind of weird that it's open during idle. So everyone else's DV is closed at idle with only 10-20 clicks clockwise. Maybe mine is defective or something.


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## giles14607 (Apr 30, 2009)

umm so i got a different question about this, i have mine about 11 clicks, and i'm running on just stock tuning for now, is that too many/ enough?


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## Mspeedy3 (Jun 20, 2009)

*Re: (WolfPac)*


_Quote, originally posted by *WolfPac* »_I just checked on this today again. When I first start the car it's closed, but after it idles down to ~800rpm then it opens a bit. A part of the brass piston is a little visible thru the small opening. The DV is connected directly to the intake manifold, N249 bypassed and I have it cranked about 25 clicks clockwise.
When I drive it around I don't hear the valve leak until I let off the gas, so I know it's holding boost properly (boosting around 18psi). It's just kind of weird that it's open during idle. So everyone else's DV is closed at idle with only 10-20 clicks clockwise. Maybe mine is defective or something.









Well at 800 rmp, there might be enough vac, and no spool pressure that it might open a bit...???
If you can see brass through the hole tho, its still closed... when the brass piston skirt starts to clear the little peanut-shaped hole, then its 'open' atmospherically anyway - but by then it should be all the way open on the recirc port. You could always throw the 'recirc only' plug on in place of the horn if youre still worried... 
I have mine directly to the intake mani also - and 25 clicks should be more than enough for 18psi, so Im told... hear thats good for around 23psi from the Forge guys...
Wouldnt hurt to check it out tho - eventhough its a piston valve (not diaphragm) there is always a chance the spring is damaged or defective...???


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## Mspeedy3 (Jun 20, 2009)

*Re: (giles14607)*


_Quote, originally posted by *giles14607* »_umm so i got a different question about this, i have mine about 11 clicks, and i'm running on just stock tuning for now, is that too many/ enough?

As long as when you snap the throttle closed, it blows down and keeps the turbo spinnin... thats good
However, on a stock tune, 8-9psi, I think it'll hold even if you back it all the way out... I bounce from between 8 and 15 Psi, and 12 clicks works fine on either tune...
Hope that helps


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## EPwho (Feb 27, 2005)

*Re: (Mspeedy3)*

Im running mine on the stage 3+ kit from APR, I have it maxed, seems to run fine with no obvious problems. You guys think I should have it set lower?


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## Mspeedy3 (Jun 20, 2009)

*Re: (EPwho)*

My best guess was to dial it up to the minimum needed spring pressure (clicks clockwise) until just a few clicks past where it would hold the maximum boost pressure I was planning to run... you could also do a leak test, pressurize the intake (again, to a few psi over you plan to run) and dial the valve until it held that pressure.
The lower you have the valve or spring pressure set, the quicker it will react when you close the throttle, and the longer it will stay open and blow down excess pressure, while keeping the turbo spinning. The purpose it to keep SOME pressure in the intake, and not slow down the compressor wheel too quickly - which minimizes the time it takes to get spooled up and back into boost after you shift and get hard on the gas again...

_Quote, originally posted by *EPwho* »_Im running mine on the stage 3+ kit from APR, I have it maxed, seems to run fine with no obvious problems. You guys think I should have it set lower?

Id dial it back a bit, if you can and still not loose boost... what pressure are you running on the stage 3? If you can dial it back and still hold your max. pressure, you should notice a bit less lag after you shift... (and a longer/louder woosh too, as it lets off more excess pressure!) 
It will still run fine if its set too tight (maxed) but it wont be opening/doing what its supposed to do, as well as it can...
Hope that helps!


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## Yosh_Cupra (Jun 28, 2008)

Thx for the comments Mspeedy3! Been tryin to fully understand this valve and a way of dialling it in since I bought it 2 yrs ago LOL! I have mine set fully clicked clockwise and am spiking 1.5bar...Going to be chaning to my k04-023 setup in the next 2 weeks and would really like to have it setup properly...Any advice would be appreciated







Any way of using VAG-Comm to set it up properly?


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## EPwho (Feb 27, 2005)

*Re: (Mspeedy3)*



Id dial it back a bit said:


> http://www.vwvortex.com/vwbb/biggrin.gif[/IMG]


I'm spiking at 24-25psi, holding around 21-22


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## Mspeedy3 (Jun 20, 2009)

*Re: (EPwho)*


_Quote, originally posted by *EPwho* »_
I'm spiking at 24-25psi, holding around 21-22

I talked to Angel at Forge recently, and on his 337 1.8t, running a consistent 23psi, and Im pretty sure he has his dialed in at about 30 clicks ( just past half way tight) and it holds/releases cleanly...
Im guessing somewhere in that ballpark should do it... but again if youre happy with the way it releases and the way the turbo spools back up, then theres really no NEED to change it...


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## EPwho (Feb 27, 2005)

im gonna try to bring it down a little bit, id like to run as soft as i can while maintaining full boost


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## Mspeedy3 (Jun 20, 2009)

*Re: (EPwho)*

sounds like a good idea... cant hurt to try!!
EPwho -
BTW - Do you really have FOUR VW's right now!?!?


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## EPwho (Feb 27, 2005)

*Re: (Mspeedy3)*

Sure do, dont know how it happened, but the 91 started it all. I love that car!


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## NOLA_VDubber (May 24, 2007)

*Re: (EPwho)*

my splitter was open at idle at every spring setting. As long as you don't have it in full BOV mode, you'll be fine as 95% of the air is recirculated back to the inlet tract..having a _small_ leak post-maf, pre-TB at idle is fine. Try running it in full BOV mode tho and you'll soon run in to problems.


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## the_champ7089 (Nov 1, 2007)

*Re: (NOLA_VDubber)*

How do u guys like the rattle snake sound?


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## gtRIguy187 (Nov 19, 2009)

*Re: (the_champ7089)*

hey guy i just got my splitter in. Im running stock setup what is a good setting for the valve to maintain full boost through throttle pull


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## a4e3y5 (Jan 21, 2009)

*Re: (gtRIguy187)*

Guys...go to the Forge website and click on the splitter. You'll get more comprehensive info on the valve. If you have the "rattle" sound under full boost you have it too stiffened, and if you don't hold that much boost, then you need to give it a few more clicks. I have mine at about 27 and no problem...i'm chipped, though. Clockwise u stiffen it, counter clockwise and it gets softer. Stock cars...try around 17 clicks.


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## gtRIguy187 (Nov 19, 2009)

*Re: (a4e3y5)*

yeah i got mine set at 15 clicks and it holds nicely.


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## paintdude258 (Sep 1, 2009)

kind of off topic, but my forge bov isnt wooshing at all. It dosent seem to be getting any pressure at all when i rev the engine up. When i rev the engine to about 5 thousand rpms while driving i hear a constant wooshing sound that dies off when i let off the gas. I also dont feel as though im getting as much boost as i did a few days ago when this problem wasnt occuring. any ideas?


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## Greg-O (Sep 23, 2006)

*Re:*

could the forge splitter be throwing a P1297- connection turbocharger to throttle valve pressure to dropped?


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## paintdude258 (Sep 1, 2009)

*Re: Re: (caracol_5)*

I'm not very techincaly knowledgable when it comes to this stuff. So your post was kind of confusing!


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## animaniac (May 26, 2005)

*Re: Re: (paintdude258)*

It's normal for the vent to be open at idle, with regards to sucking in air i think you will find that with it being post turbo but pre throttle theres isnt any vac in the pipe only pressure.
Get a little bit of tissue and hold it infront of the valve, and you will see it's blowing out air.
All dv's are open at idle due to vacuum on the dv vac pipe, only when boost starts being produced does the valve start to close.
Some valves like the hks ssqv have springs inside them which keep it closed at idle, but even theses start to open at part throttle again due to vacuum.
The only problem with vent to atmosphere valves is they make the engine run rich, by how much varys, and this may or may not affect the emissions!
I think your pretty safe with the split-r.
I posted a post about how i struggled to pass emissions test with the splitter, but i think the 4 bar reg i put in affected it more than the splitter did hense the valve venting slightly just sent the emissions over.
I've stuck the 3 bar fpr back in and performance wise it's not affected it that much, it's started shugging slightly on and off, i think my fuel filter needs doing.
Even enough it passed the emissions with the 4 bar, there have been many roadside tests last year, and i'm pretty sure they will be cracking down on vehicle defects / emissions this year in the summer and i don't fancy getting a damn fixed penalty ticket for emissions failure then have to pay a garage to retest emissions and then have to report back to the cop shop....
This is what happens when folk remove the cat and then it fails emissions by running too rich







obviously a roadside emissions nightmare..


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## NaudifreakTT (Jan 22, 2010)

*Re: Re: (animaniac)*

did you guys notice a drop in fuel economy when you installed this? and my exhaust seems quieter as if it is running a lot richer...


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## joe'sGTI (Jun 12, 2007)

*Re: Forge Splitter BOV/DV Issue (20s2VW)*

get rid of it. I had one and loved it the sound was awesome. Buddy convinced me to put on his R1 and the feel and responsiveness was WAY better.


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## steve-o 16v GLI (Jun 26, 2005)

*Re: Forge Splitter BOV/DV Issue (joe'sGTI)*

really? I had a 007 before my splitter and the splitter is deff. faster and it reduced my boost spikes and sounds awesome. and it would hold 12lbs some times at redline,it never did that before







I wana actually run it full bov some time for fun! since Im on mk3 management it shouldnt cause any problems.And ive never heard it/heard of anyone trying it that way.


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## ExPensiveTaste (Feb 10, 2010)

Got the splitter on my B6 and it seems to be giving my Revo problems. 
Any Help?


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## alpinegolf (Apr 21, 2007)

*Re: Forge Splitter BOV/DV Issue (20s2VW)*

dont run splitters or blow offs...just divertors. vw/audis need complete recirculation of air with no atmospheric blow off


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## 2k4BlackMagicGLI (Mar 10, 2006)

*Re: Forge Splitter BOV/DV Issue (alpinegolf)*

The valve is a hybrid, it is designed to both vent to atmosphere as well as recirculate with out any adverse effects.


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## @lex20th (Jul 28, 2009)

*Re: Forge Splitter BOV/DV Issue (alpinegolf)*

Get Forge 007... or any full diverter valve


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## lebedevster (Aug 6, 2009)

*Re: Forge Splitter BOV/DV Issue (beetle @lex)*

The splitter has a cap to make it a full diverter or full blow off valve. This gives you the option of using either method in which lies it genius. Some days you may want to show off and hear the blow off valve, other days you want to smoke someone off the line. With a 007 you have option B. With splitter you have both. Sounds like a winner to me.


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## bahnblitz (Jan 18, 2002)

*Re: Forge Splitter BOV/DV Issue (lebedevster)*

I had them on my 2.7T allroad and they worked great. Sound wasn't obnoxious at all. They are a tight fit and adjusting while it is installed is a pain.
No springs to lose like a 007!
Get a boost gauge or log with VagCOM so you can see how much boost you are running while setting it up, takes the guess work out


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## foxhound720 (Sep 11, 2003)

*Re: Forge Splitter BOV/DV Issue (bahnblitz)*

I have a forge splitter and a AEM trub boost gauge.
If I run BOV for ****s and giggles my idle vacuum reads -19 -18 But I dont run pig rich.
If I run DV or hybrid my idle vacuum reads -20 -19 like normal operation. It doesnt effect my readins that much. My point is DV mode is the same as hybrid mode because it allows 80% to 90% air to recirculate, So a splitter is a good adjustable valve.


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## animaniac (May 26, 2005)

*Re: Forge Splitter BOV/DV Issue (foxhound720)*


_Quote, originally posted by *foxhound720* »_I have a forge splitter and a AEM trub boost gauge.
If I run BOV for ****s and giggles my idle vacuum reads -19 -18 But I dont run pig rich.
If I run DV or hybrid my idle vacuum reads -20 -19 like normal operation. It doesnt effect my readins that much. My point is DV mode is the same as hybrid mode because it allows 80% to 90% air to recirculate, So a splitter is a good adjustable valve.

You sent me a pm asking a question about the forge dv but you didnt say what the question was but seem to know about them??
Making any kind of partial throttle boost leak will cause a certain amount of richness to the air/fuel ratio, the 02 sensor will correct this to a certain degree, this is what happens when you run a bov, some bovs say they only open / vent off when your at throttle lift off.
But the splitter works the same as the standard dv except it's adjustable pressure wise and you can make it recirc aswell as the hybrid mode making alittle pressure venting to the atmosphere, giving you a little whoosh noise without causing any kind of running problems due to the amount of air being vented off is more than corrected by the 02 sensor.
Where as the fully atmos mode is a no no, ecu doesnt like it, causing alittle jerkyness and throws the 02 mixture adaptation code.


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## ManikGTI (May 18, 2009)

*Re: (the_champ7089)*

The snake sound is turbo surge make sure the large port on the splitter is the one your using to circulate the air. from what i hear the forge slitter is adjustable to 26 pounds with 52 notches to tune it properly tighten the valve to the lowest amount of clicks clockwise so that you dont bleed off at WOT. I also heard that it doesnt really matter about the splitter if you still have your n249 still in circulation. Just food for thought
-frank


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## foxhound720 (Sep 11, 2003)

*Re: Forge Splitter BOV/DV Issue (animaniac)*


_Quote, originally posted by *animaniac* »_
You sent me a pm asking a question about the forge dv but you didnt say what the question was but seem to know about them??
Making any kind of partial throttle boost leak will cause a certain amount of richness to the air/fuel ratio, the 02 sensor will correct this to a certain degree, this is what happens when you run a bov, some bovs say they only open / vent off when your at throttle lift off.
But the splitter works the same as the standard dv except it's adjustable pressure wise and you can make it recirc aswell as the hybrid mode making alittle pressure venting to the atmosphere, giving you a little whoosh noise without causing any kind of running problems due to the amount of air being vented off is more than corrected by the 02 sensor.
Where as the fully atmos mode is a no no, ecu doesnt like it, causing alittle jerkyness and throws the 02 mixture adaptation code.


Yeah we all know this by now. Like I said I did it for ****s n giggles around the block. I Wanted to ask you if people use them after they have gone big turbo or did they just switch to a larger setup for DV/BOV ? 
I was going put the question on the thread but i found my answer.



_Modified by foxhound720 at 8:21 AM 4-22-2010_


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## foxhound720 (Sep 11, 2003)

*Re: (ManikGTI)*

The little snake sound is valve flutter. Turbo surge sound is wicked loud and scary. lol


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## animaniac (May 26, 2005)

*Re: Forge Splitter BOV/DV Issue (foxhound720)*

I think most folk running a big turbo just use their uprated valves, including the splitter, the splitter hybrid whoosh noise will get louder when running higher boost pressures due to more pressure on blow off.
Another thing about having the splitter for a big turbo, is the spring rate can be adjusted by a few clicks of the ratchet if the valve isnt holding the higher boost levels.
Can be troublesome when using the normal valves and swapping to different stronger or weaker springs and adding shims, sticking it all back together, drive around the block only to find, it's either not holding boost properly or it's causing compressor surge, resulting it taking it all apart and messing around again. 
The splitters a sensible valve, and even for those people who don't want the blow off sound it's a fully spring rate adjustable recirc valve with added blow off, for those you want it.
A fine peice of engineering i say.


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## foxhound720 (Sep 11, 2003)

*Re: Forge Splitter BOV/DV Issue (animaniac)*

I agree. Its nice. I think I am on 25 clicks now and works great. Forge just mailed me the upgraded internals for the splitter for when I go BT sometime soon. Nice people over there. 
If I tighten the splitter in the high 40's to 50's as far as clicks you will get the snake sound called valve flutter because the piston has such a small amount of room to move up and down.
Hence why they sent me the upgrade. 25 clicks would be like 52 clicks on standard internals.


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