Anti-NA

I just want to clarify what he just said only applies to DSM. If you were to put the exact same BOV/DV on a Honda or a custom turbo, IT WILL NOT "SUCK" AIR IN AT IDLE.

d16forlife

Not true.All deverter valves(bosch,dsm,the ones off of Volvos)will be open at idle.Its not the make of the car that makes it open so it doesnt only aply to DSM cars.Like I said before ALL diverter/BOV valves open at vacume.Th eonly ones that wont suck in air are the dual diaphram ones like Semnos said.

Im using one off of a Vovlo(all aluminum with ).It sucks air at idle couse its a single diaphram diverter valve.


Quadnie your right in the sense that cars like My VW passat have sensers that will throw a CEL if it senses a loss in pressure or a change in air volume.They make a BOV/diverter that vents 1/2 of the pressure to the atmesphere and returns the other 1/2 back into the charge pipe.It sounds really low and its really pricey.Not worth it IMO.

Factorys use diverter valves not only becouse of the mas/maf meters but also couse most people would be driven up the wall by the sound of compressed air being released everytime the car goes into vacume.

And not to change the subject but cars with mas/maf sensors are easier to tume for boost.Just a simple chip can up the boost as much as double.......map sensors suck :P

Anti-NA

I have never said they don't open at idle, they do but they just dont' suck in air in most cases.

quadnie

Damn Rafeal, all this time I thought you were as smart as a turnip.. who wouldn've known you get them mad skillz.

Anyways, back to the dsm cars. Yeah, I'm familiar with the dual chambered BOVs that recirculate half, vent half. But ---- spending $300 on one, plus I've only seen them made for Subaru cars. See all these DSM guys have this thing for venting.. yeah they have a factory turbo car, no the little peel off badge of GST/GSX/TSI just isn't good enough for them. I'm yet to see the dual function BOVs meant for an eclipse.

So now there are two problems with capping off your bov return flange.. first, the single diaphram bov sucking air into the car at idle, thus raising the A/F ratio (probably not by that much).

The main problem is that the MAF sensor meters air coming in (before the turbo, right after the air filter). And the BOV is meant to reintroduce the charge line's air back into the system (between the turbo and the MAF). When it gets vented instead, the ECU has already compensated for that extra air that just escaped, thus the car puffs some smoke between shifts from the over production of fuel. Worse yet, the cars will stall out at low rpms. Yeah, most of you already knew that, but I'm giving people some heads up anyways since this thread will be going into my newbie FAQ.


My next question is, any of those dual purpose BOVS dual diaphrams?

d16forlife

Ok dude I dont want to argue but you make no sense.

If the car is on.The throttle plate is closed,so the manifold has vacume(the nature of an internal combustion engine is to want to feed its self to death).Ok now if the manifold has vacume and the diverter is open couse the diaphram is sucked open by the vac line that comes off the mani....you with me.Ok my point is that if the charge pipe is conneted to that throttle body and the diverter is on the charge pipe thats on the throttle body while the engine is trying to suck in air from where ever possible how would the diverter not be sucking in air if its open?

To my understanding it is a dual diaphram.I think it would throw the ecu for a loop if it were open at idle sucking in air from the side that vents to the atmesphere.Thats on the one that I saw for the VW though.

Also I think the DSMs are ok with venting into the atmesphere couse like you said the air has allready been acounted for and they must not have a meter down stream that would tell the ecu like the VWs have that there is more incomming air than necessary.Its only sucking a little more air at idle while its open or durring shifts.Most DSMs that Ive seen run a Greeedy Type S bov.I belive that has a dual diaphream too

Oh and quadnie I do actually know a little bit here and there but Im still learning

Anti-NA

I'm not familiar with DSM, but let's just say a DSM bov/dv regardless first or second gen was used on a b18, it will open at idle but air will be coming out, not in. The reason i'm so sure because I have experience with it first hand and have seen others that acted in the same manner.

Carnesd

How is air coming out? There is not positive pressure in the charge pipes. It is under vaccum, therefore the air is being sucked into the engine.

Try this: hook up a Diverter valve (bosche style bov) to any vaccum source on your car. Don't have the bov hooked up to your charge piping. You can blow through it when your car is sitting there idling.

The reason is that the vaccum line you connected to the bov is "pulling" on the diaphram and the bov opens, when you go into boost it presses on the diaphram closing it.

When you let off the throttle quickly, your going from boost to vaccum. And since these style bov's open at idle, thats why some people say they hear a long hissing after the let off the throttle, because the turbo is still spinning and trying to create boost, but since your engine is in vaccum, the air that the turbo is pushing, is coming out the bov.

stinky

Your car at idle is under full vaccum.Which means,like a vaccum cleaner,it is at full "sucking" power.If the diverter valve is open,then the vaccum in your intake is going to "suck" air through it no matter what car its on.

bulldogg9279

my 1g bov blows air out at idle not sucking; but the reason this is ;cause i have a little IHI; it never stops spining

Speedracer32

ok some of this was confusing but just to see if it sucked in air at idle

couldn't you just start you car up and put your hand over it to see if it sucked