Stock BOV...choosing to vent to atmosphere?

[Steve Theodore]

This question is being posted for a friend, who cannot access the Supraforums from work:

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What I would like for you to post if you can is to see if anybody has vented their stock BOV to the air. If so did they like it and were there any adverse side effects? Andi told me about it and I am going to try it next week but I wanted some feedback on it
first. I had never heard of someone doing this. All you have to do is take the hose off the back side of the BOV and cap the BOV with a 1" cap.
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Anyway, if anyone wants to give this one a crack, have at it. I don't personally have any knowledge about doing this mod so was unable to offer any help or advice. Thanks.

Steve T.

[Park]

It won't work unless you're either running a VPC or an HKS AFR w/ the EIDS function on. It's a non-issue with a VPC and the AFR just basically tricks the computer by momentarily adjusting MAF output based on throttle position (i.e. letting of the gas with a quickness). If you vent to the atmosphere, you end up pulling air through the MAF that gets metered but then dumped in the atmosphere. In stock configuration the "bov" is more of a bypass valve and recirculates the air when bleeding boost instead of sucking more air through the MAF.

[Park]

I guess I should have added the consquences - the car will stall on decel or at least idle like complete crap if you do it w/o a VPC or AFR. Of course speed-density based engine management systems will get the job done too...

[463supra]

I was the one that had Steve post the question.. i cannot post from work. i figured there was a reason no one else did this.
Jeff

[NOVAsupra]

I have an aftermarket bov that i vent to the atm, i have been doing so for several months with no problems whatsoever, no stalling, hesitating, bad idle, etc. I imagine the stock bypass valve vented to atm to perform similarly, unless it functions drastically different from the standard bov.

[Josh S]

what would be the advantage of doing this? Woud the BOV be louder? I can't even hear my stock BOV at all with the stock airbox.

[MystiqueSupra]

My supra, along with 20 other supras here all vent to the air. No one recircles the BOV.

* Fyi- only 3 of them have VPCs.....the rest are stock.

They dont have bad idle,stall,or hesitatie... etc.
I dont like to argue, but YES it is possible to vent the BOV without a VPC.....and have the car run good.

[Supraholic NYC]

The main problem with venting a bov into the atmosphere on a mass air car is, the mass air sensor has allready measured and calibrated the air flow into the motor. By venting the air you have effectivly created a lean condition in the engine. It will be a slight lean condition as the bov is not that large, But a lean condition none the less. With a speed density system (vpc) this is not a problem as the air volume is calibrated from the actual manifold pressure.

[Josh S]

Originally posted by Supraholic NYC
The main problem with venting a bov into the atmosphere on a mass air car is, the mass air sensor has allready measured and calibrated the air flow into the motor. By venting the air you have effectivly created a lean condition in the engine. It will be a slight lean condition as the bov is not that large, But a lean condition none the less. With a speed density system (vpc) this is not a problem as the air volume is calibrated from the actual manifold pressure.

Actually you will create a rich condition not a lean condition. You will end of with less air entering the combustion chamber than was metered, so the injectors will injet extra fuel for this metered air. It's the same as having a boost leak, you will run rich between shifts.

[Supraholic NYC]

You are correct, not making excuses but i am trying to answer phones and do some shipping at the same time. But yes a rich condition will occur.:o

[Zerosoul]

I am running TTC mode and I have currently took off my HKS SSBOV (stock position) and put back stock BOV. weird thing is that when I let go of the gas after building some boost the BOV sounds almost as loud as my HKS SSBOV. I have checked and all vacuums are tight and in right place. how can that be?

[supra400hptt]

My turbo xs is working perfect going to atm. Main reason I got it is to be able to hear when it's working. Could never tell when the stock BOV was working or not. Back then I was having problems and a lot of people were blaming the stock BOV for bad idle etc.

[463supra]

OK everyone...I did this MOD yesturday and you can definitly hear the BOV venting. BUT it does Idle poorly and has stalled several times. The idle is not as bad if I have the AC on for some reason but it still get to very low RPMs when I stop at a light or sign after driving. I have to say I do like the sound quite a bit. Looks like I will be investing in a aftermarket one afterall..:D
I will be putting the hose back on this weekend.
Jeff

[supra400hptt]

Sounds like it may be leaking a little. Also, did you plug the hole from where you took the hose off at?

[463supra]

Yes I plugged the hole on the intake. I left the BOV open. I put it back on today before I went to the UTK game. I got tired of trying to catch it before it stalled when I would stop. I burnt the crap out of my fingers trying to put it back on with the engine hot.
Jeff