g6civcx

(read below for description). Are you running the side mount intercooler or did you upgrade to a front mount?

I recommend getting the SARD BOV kit. It comes with a hard pipe to replace the factory plastic hotpipe and has the flange for the BOV. Very nice piece.

kazuo

What?

People run no BOV all day long, and their cars idle perfectly fine.

g6civcx

It was late and I lost my mind

Let me rephrase. At idle the BOV should stay completely close as to not affect vacuum. If you have a leak somewhere, it's going to affect the idle. Theoretically not having a BOV should seal up the system at idle, but sometimes it's not that simple.

Even under slight boost, when you lift off the throttle you're going to have compressor surge. Extremely bad for your turbo and the car is going to stumble a bit. A bad BOV will cause the same thing.

The reason I said no BOV can cause a bad idle is because we spent a lot of time ironing out the bugs in my car. We finally tracked it down to the defective BOV. At idle it would stumble and stall. Off-throttle it would stumble and stall. We took out the BOV and plugged up the line, and theoretically it should be stable at idle, but it did the same thing. Now we installed a SARD BOV with the correct spring rate and it idles perfectly. No stalling. No hesitation. No off-throttle stumbling. Works perfectly.

It's completely stupid but the BOV was the single most effective adjustment we made to the car. Now it drives 1000 times better. I think the BOV itself and the flange were leaking, but whatever it was the SARD BOV fixed it.

Now you can choose to run without a BOV, but ideally if you have the stock recirculating plumbing just run that if you don't want to spend money. You can try running w/o a BOV just to get it started. Just make sure you plug up all the line, but don't be surprised if it runs a little rough.

IAM_SO_sLOw

o i see... yeah i did a search about people who dont run bovs...im running a stock sidemount btw.... well thanks for the help guys...

kazuo

The car will run perfectly fine without a BOV.

Ask dirtydousan, his boy nekopunch up in WA has been running without any kind of BOV/Recirc for awhile.

And he isn't the only one.

The car will run fine. Obviously you will get compressor surge, but the car isnt going to "stumble" or anything as a result. The "stumbling" occurs with atmospheric BOV due to the fact that we have a MAF sensor.

g6civcx

Like I said above, theoretically if you plug up the lines it will act like a closed BOV under idle, but the problem is if you have a slight leak anywhere in the system it will cause the stumbling problem I mentioned. We traced my problem to a leaking flange. So even if you think you've plugged up everything, it's always best to make sure you tighten all your air and vacuum lines.

Now I wouldn't recommend running without a valve of some sort for reasons stated above. The best way is to run a recirculating valve since the MAF has already metered the incoming air. If you vent it, the motor may stumble a little bit as the air it's expecting doesn't show up. If you have a whole front clip, just run the stock plumbing. You can also run a vent to atmosphere (VTA) with little ill-effects if you use the correct stiffness.

A few people may be running without one with no problems, but that's just a few people. If you're having problems just plugging in the lines and getting the car started I suggest you try to stay as close to the factory design as possible just so you can get it started. Then worry about modifying it later.