Blow through MAF?

[Rays_240]

My question is 2 fold. Im currently doing an sr swap and I understand that I need to recircualte by bov and I also understand the reasoning behind it. Ive been doing alot of searching and found alot of people talking about putting their maf after the intercooler. Im looking for info on this. I know i should use a z32 maf for this but will I need a tune to do this or will the maf read the same as if it was on the intake? Also for the z32 maf do i need to do anything besides the wiring, or will it read the same as the sr maf? Anyone with real experience please chime in.

[PyR0NiAk]

Haven't looked into the maf after the intercooler, but you'll definitely need a tune for the Z32 maf.

[Rays_240]

alright thanks, Im basically looking for a way to not recirculate the bov without causing any problems

[PyR0NiAk]

Learn how to tap the throttle with your heel during decel.. It's not that hard

[Second Shadow]

recirculating doesn't "cause" problems, it "fixes" problems. you see the air that an atmospheric BOV vents is air thats been read by the maf, and the ECU is going to inject fuel expecting it to be there. it won't be though so you run rich for a moment. when you recirc you put that air back into the intake track, after the maf, instead of venting it. which means all the air that has been read by the maf will make it to the cylinders. it doesn't loose any air along the way, or read anything twice.

also if you do it right(like it is from the factory) the air will blow out of the BOV into the intake track at an angle that basically "blows the air at the compressor wheel", like wind through a windmill, keeping it spinning and saving you lag time on getting back up to full boost again. basically the exact opposite of compressor surge. note: this happens regardless of maf location.

on the blow through maf;
some people do it, it works. the advantage is that it reads right before air enters the manifold, so any problems in the intake track won't effect engine performance, like a boost leak.(an atmospheric BOV is actually a tiny problem as viewed by the standard maf location, but not when using it blow through).

I personally don't like the blow through maf. it moves away from the closed circuit design mentality of these engines, meaning any and all air that enters the intake track is fully accounted for until it leaves the tail pipe. and problems with your intake track will be harder to notice(doesn't mean they aren't there).

[PyR0NiAk]

recirculating doesn't "cause" problems, it "fixes" problems. you see the air that an atmospheric BOV vents is air thats been read by the maf, and the ECU is going to inject fuel expecting it to be there. it won't be though so you run rich for a moment. when you recirc you put that air back into the intake track, after the maf, instead of venting it. which means all the air that has been read by the maf will make it to the cylinders. it doesn't loose any air along the way, or read anything twice.

also if you do it right(like it is from the factory) the air will blow out of the BOV into the intake track at an angle that basically "blows the air at the compressor wheel", like wind through a windmill, keeping it spinning and saving you lag time on getting back up to full boost again. basically the exact opposite of compressor surge. note: this happens regardless of maf location.

on the blow through maf;
some people do it, it works. the advantage is that it reads right before air enters the manifold, so any problems in the intake track won't effect engine performance, like a boost leak.(an atmospheric BOV is actually a tiny problem as viewed by the standard maf location, but not when using it blow through).

I personally don't like the blow through maf. it moves away from the closed circuit design mentality of these engines, meaning any and all air that enters the intake track is fully accounted for until it leaves the tail pipe. and problems with your intake track will be harder to notice(doesn't mean they aren't there).

You should read more... Especially before making lengthy responses..

alright thanks, Im basically looking for a way to not recirculate the bov without causing any problems

[Rays_240]

thank you pyro, I undrstand the whole recirc thing perfectly. taping the gas while decelerating is fine but I cant heel and toe, my feet are litterally to big they just dont fit sideways lol

[PyR0NiAk]

You could always do what I do... It's not recommended, because a miss could cause you to come off the brake when trying to stop...

What I do, is I only hold half of my foot (left side obv) on the brake pedal, and then, I pivot my foot to tap the gas pedal...

I learned how to do it before I had any idea what heel-toeing was and my Beretta kept going through map sensors..

[Rays_240]

yea ive done that before, kind of a pain. Im just gonna recirc it and hope it still sounds good. If not ill just jigure something out

[DuckyD]

yea ive done that before, kind of a pain. Im just gonna recirc it and hope it still sounds good. If not ill just jigure something out

Good call.
Talking to Scott (formally of Enthalpy) in the past, he was not fond of blow-through MAFs.
The MAFs are prone to causing problems when air is not normalized while going through the MAF. Depending on the angle of bends before the MAF, air may enter the MAF turbulantly and cause running issues. The benefits are there for having a blow-through MAF (particularly being able to run even if you blow a coupler, and the recirc as you mentioned). But for my time and money, I would rather know that my first attempt at intercooler piping and intake piping is going to be right. There is a reason that you don't see kits offered with blowthrough options.

As you also asked, you cannot run the Z32 MAF without some sort of tuning. SAFC can compensate or you could go with an Enthalpy or JWT tune ($400ish). The Z-MAF runs different voltages than stock SR MAF.

That being said, having a BOV that vents to atmosphere isn't ideal but it works for mostly everyone that runs it. My HKS SSQV is vented to atmosphere (not recirculated) and stalled a few times when I first intalled it. But the ECU learned and my car has not stalled on decel in 3 years. The Nissan ECU's are eprom and really good at "learning" new variables. Certain BOV's seem to do better than others on the SR, as far as stalling issues are concerns.

[Second Shadow]

You should read more... Especially before making lengthy responses..

alright thanks, Im basically looking for a way to not recirculate the bov without causing any problems

there are few words to describe how stupid I feel right now.

[OM3GA]

lol

[CRyan]

You would need tune with Z32 MAF? Why have I thought that the MAF is only reading the CFM passing through and sending it to the ECU to allow register of air moving?

Am I just completely off on that, or am I in the ballpark?

[PyR0NiAk]

Z32 maf has different voltage...

[DuckyD]

Z32 maf has different voltage...

+1

[vocationalzero]

Like DuckyD says with atmospheric. I run atmospheric as well, I have a greddy type rs, the purple one before it became blue, and I have never had my car stall with it or with a problem with it.