question on by passing bov's

[reef_chameleon]

A guy who works at a performance shop here in my area had told me that i could disconnect the hose that is connected to my bov that is connected to my intake to have a better sound from my bov. I also capped that hose off so that no other airflow would get into the intake. well i did it and it sounds really good but when im stopped and idling the motor sounds like it wants to die. So i put everything back together and it was back to normal. was i doing something wrong or did he give me some bad info. The sound of the bov was awesome i just didnt like the way the motor was running.

 

[turbosax2]

http://www.dsmtuners.com/forums/showthread.php?t=113858

 

[blktalon3]

The guy at the performance shop is wrong. The hose that connects the bov and the intake is there for a reason. It routes air that the maf has already accounted for back into the intake. If you disconnect the hose it releases metered air into the atmosphere and causes a rich condition. The only way you can run an open bov is with a stand alone fmu or a blow through set up with a gm maft.

 

[ricktb]

the computer measures the air entering the intake using the mass airflow sensor. Then it adjusts the amount of fuel to match the air coming in for a good combustion ratio. When you take the pipe off the air escapes, and the computer doesn't know that so the fuel to air mixture is now messed up. There are ways to get around this, research "vent to atmosphere".

Theres other performance pros and cons to doing this, read up.

edit: I got beat to it darn

 

[reef_chameleon]

thanx for the advice. I knew there was something wrong when the motor was running weird. it is a good thing i put every thing back the way it was. thanx

 

[MrBoxx]

A guy who works at a performance shop here in my area had told me that i could disconnect the hose that is connected to my bov that is connected to my intake to have a better sound from my bov.

He's correct, but an idiot. Don't go back there.

was i doing something wrong or did he give me some bad info.

Both. Yes, venting to atmosphere without the proper modifications is wrong, and not good for the motor, regardless how many people say they've done it without any noticeable problems. The bad info that he gave you was that you could do it without any other modifications, such as a MAF and translator setup or MAP setup or speed density, or whatever other things you'll need to do this correctly.

Edit: Now go do a boost leak test to make sure you're not leaking from anywhere.

 

[Talesin]

In addition, our cars come stock with a CBV, not a BOV. The main difference between the two being that a CBV is open under vacuum... like at idle, or under light throttle. It's so the turbo won't be quite so much of an intake restriction, allowing light-throttle use to simply bypass the turbo entirely.

The reason this is important is that not only do you lose metered air when you vent a stock draw-through MAS setup to atmosphere... with a CBV, you're also pulling IN UNmetered and worse yet unFILTERED air, making you run even leaner at idle than stock, which already leans the car out a lot to conserve fuel.

Short version, the guy was right about it making the blow-off sound louder. However, he's also an idiot when it comes to DSMs and our turbo arrangements. Don't go back. He might be one of the 'performance' shops that stock carbon-fiber-look stickers, light-up 'racing' pedals, and huge chrome exhaust tips. Otherwise known as a rice shop. Have a few of those around here... when you ask them for an actal go-fast part, they tend to just look at you stupidly, or say that they'll have to order one, and jack the cost WAY up. One wanted over $300 for an MBC, when I was looking for my first one.


If you just want a louder blow-off sound, get a hard intake pipe and do the MAS noise reducer elimination (on a 1G anyway, can't remember if the 2Gs had the star silencer or not). Hard upper intercooler pipe as well if you can afford it. It'll make it MUCH more noticeable, and the car won't run like half-dissolved leper ass. Plus, it'll add power as a 'side-effect' as your intake air won't be as turbulent as with the stock rubber snorkels.