""Thats not necessarily true. THe reason why VTA causes stalling in cars depends on the placement of the MAF sensor. If you put the sensor just after the air filter pre compression then the air that is being blown out of the BOV is still being accounted for in the air/fuel readings because technically the car says "ok the air came in, unless theres a leak it can only go to the engine, so lets count that air". It you place the MAF just before the TB between the throttle plate and the BOV then the air is being counted by what is entering the engine and if air is being vented to atmosphere then it is not blowing through the MAF. So basic rule of thumb (if your air flow sensor is placed just after your air filter before the intake on the turbo, then you will need to vent your bov back to the intake plumbing. If it is placed between the throttle body and the bov, then the sensor is reading the air left over after the bov has already vented, so it accounts for what is actually entering the engine. In either case with the turbo'd 4g93 the air flow sensor can still read the air entering the system up to around 9 or 10 psi if placed on the pressurized side of things. after that you are overrunning the sensor and you need to place it on the intake side of the turbo or upgrade"" I got this from another thread, i have heard of some people pressurizing there MAF by putting there MAF between there bov adn intake manifold, instead of it being your MAF then your bov then your manifold. I actually had this planned for my car in about week when my other parts come in so i can bookst a little more. From hearing peopel talk about it it seems pretty straight forward and easy, i meen is what i read on that guys quote all there is to it? All i know is a guy on here from PR who turboed his RA said just make sure you bov is more towards your intake filter, then your MAF 6-12 inches behind that and you should be good, thats what he did. Andy thoughts???? Thanks guys.

 

I re-read your first post, and I have three questions:
1) I know you mentioned that the flutter sound happens ever since you had your kit finished, but has it changed since day one (i.e., gotten progressively worse/more pronounced)?
2) If yes, when you cleaned your air filter, did you check the MAF...if it was clean?
3) Have you noticed a change in relief letting off throttle (BOV opening slower/quicker than it once did)? What I'm getting at here, is did something change with the BOV...not seated the way it once was, etc.

Regarding Booster's comment, I'm running a Synchronic and have had no flutter, but I don't think that's enough justification to go out and replace something that may not need replacement.

 

Thanks Raven, well it was weird, before my bov was recalculated, the guys who did my car said hey come on over to the shop the car is done just a few minor tweaks and your set, we will give you a quick ride. So he did, pulled in second and the bov opened and it was loud sounded great. But with most none turbo cars didn’t like VTA. So they recalculated it, ever since i got it back the second time and it was all tuned it has sounded the same. Now like I said before in the previous post it states when it sounded great with no filter on the intake and no recurc tube, just ran rough. But then when I plugged the recurc tube it shut off….weird. I cleaned my filter and my MAF last night, stuck everything back on the way It was and back to fluttering . I know it cant be just the filter im using can it? Well in a few weeks when I get my AEM uego gauge/sensor, boost controller im remaking custom IC pipes and intake pipes, and I am pressurizing my bov, which I heard works for people putting your bov first, then your MAF 6-12 inches behind that, so I can VTA. Because one thing I noticed that really got me was yeah it idles rough with no recurc tube on the bov, but boy did it shift smoother, didn’t buck down when I shifted, so I don’t know what happened. Doesn’t always shift rough just sometimes, did that help at all raven?

 

and yes i agree, the bov does'nt need to be replaced, because it worked great last night when i took the recurc tube, i think i just need to pressurize the MAF like some people do

 

And im not sure if i answered 1 question, yes it has sounded like that ever since i got it, and it hasent gotten worse, but the turbo sounds like it is'nt spooling or spooling different and the blow off vlve sounds significantly different when that happens.

 

Could be surge. Need to see a pict of your custom setup to note placement of stuff. Also need to see vacuum line arrangement.

ROAD/RACE

 

Ok i wont be able to do it this weekend, but next week i will get some pics to show you, thanks rock. One for you, di you understand what i was saying about pressurizing your MAF, not sure if thats the correct terminology because it is the first time i have researched people doing it. But could it be a vacuum issue? Because when i take the recurc tube off the bov it blows off fine, but then the recurc tube is off the bov and then i cap it off the engine will stall out, dont quite understand that. This is why i i have been researching presurizing your MAF and looking into it next weekend when my car goes into the shop to get some boosting mods put on my car, i told the machanic who help with my custom set up to go ahead and plan on redueing all my IC pipes and intake pipes for 1 a shorter intake and 2 putting the bov before the MAF so it doesnt have a problem with blowing off that air and makign the engien run rich, thanks again your help is much appreciated!

 

^Rock brought up my next question, about placement (i.e. of the recirc. dump tube in the intake tract).

I looked up Blitz DD BOVs, apparently the DD is for "Dual Drive," so it has two ports...a small one for low boost and a large one for high boost. Do you know what the threshhold is for each port? Maybe 5psi is right on the border, which is why sometimes it shifts OK and other times it doesn't. If that's the case, maybe a different configuration of vacuum lines or adjustments on that nut on top might help? I tried to look up the BOV on Blitz' website...discovered I need to brush up on my Japanese, and quickly remembered I'm a midwestern white guy...

Regarding the pressurized MAF, there's an interesting article in the latest Import Tuner; they tested venting the diverter valve on an Evo X to atmosphere (stock it's recirc.). Pressurizing the MAF is going to be needed if you want to VTA (I think you already knew that though )

 

Just took the recurc pipe off and i drove it around the bplock a few times at various rpms and it drove perfect, just iddled a little hard sometimes, so what i want to know is why when my recurc pipe is on it shifts worse, and sounds worse?

 

I'd have to see a photo of your setup to know for sure what's going on.

In general pressurizing a MAF is a bad idea. Turbos, even brand new will always spit a little oil into the intake tract. MAF sensors don't like oil. Most you can clean with brake cleaner but as the little droplets of oil hit the sensor element they can cause it to deliver a progressively less accurate signal. Since fuel delivery is directly proportional to the amount of air being delivered you then put your entire engine at risk.

The problem with atmospheric BOV's is that they will often leak on rundown because your engine makes a lot more vacuum on decel. This leads to stalling every time you roll up to a stop since you end up with a lot of unmetered air drawn into the system.

The second problem is on a gearshift, the metered air escapes and you end up with an inrush of fresh air to replace it. I started writing a custom routine for a different ECU that switches between using speed density (MAP sensor) and direct airmass measurement but ultimately it's very difficult to tune because you basically have to tune the car using each measurement system then switch between them when the two calculations disagree. UGH!

Since I'm so busy working out all the different calibration data in the ECU it's unlikely that I will have a chance to release such a thing anytime soon.

-Michael

 

Currently in Philly at my gf's apartment, i will have pics and answer you guys tomarrow, did'nt want you to think i was ignoring you

 

Thought you said you had pics?

ROAD/RACE

 

Yeah but there on my e-mail account, cant save them to this computer, om on my work computer and they disable that, and my computer is fried.

 

So if anyone wants to see them, just give me there e-mail adress in a PM and i will send the pics i have 3 of them, of my set up.

 

OK guess now one wants to see hte pics of my set up since i cant post them on here, i only have them on e-mail, thanks anyway guys. Im having my new IC and intake piping made, im putting my MAF just before my 5th injector and the bov about a foot down from that, so i will be VTA, plus im boosting to 10psi with the new aem uego gauge and new boosts controller should be able to geta goodaccuate tune, and should fix the problem, thanks for anyone who posted here.