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View Full Version : does anyone here run a relocated bov/dv or maf?



bbkid43
08-06-2007, 01:56 PM
just wondering if anyone here has relocated thier maf so they could run a bov...is that possible? i am thinking bout a custom fmic and thats somthing i might want to look into.

TMorris
08-06-2007, 02:10 PM
you want a diverter valve not a BOV. ive heard bad stories about BOVS

SurferForever
08-06-2007, 02:16 PM
just wondering if anyone here has relocated thier maf so they can run a bov...is that possible? i am thinking bout a custom fmic and thats somthing i might want to look into.

huh? what would that do? If you really wanna do something wrong and install a BOV in your car it would just go where the stock DV is. But it will make your car run rich. Why would you want to relocate the MAF? what would that accomplish?

bbkid43
08-06-2007, 03:11 PM
i know your not supposed to run a bov in stock location. what i was thinking was that you might be able to relocate the bov and maf onto the hot side so it would only see the air that is coming into the engine like it is supposed to....so you could use a bov and have it push all the hot air out instead of a recirculation setup...

TMorris
08-06-2007, 03:14 PM
what would that accomplish?

X2

SurferForever
08-06-2007, 04:19 PM
i know your not supposed to run a bov in stock location. what i was thinking was that you might be able to relocate the bov and maf onto the hot side so it would only see the air that is coming into the engine like it is supposed to....so you could use a bov and have it push all the hot air out instead of a recirculation setup...

What year is your car? If its DBW, your still gonna messup the MAP sensor. The ECU is made to run with the set-up how it is. If you move all that stuff its not going to make a difference because its still going to be fueling for the air in which isnt going to be there. It doesn't make a difference where it is because the ecu compensates for it automatically

maxspeed
08-06-2007, 04:23 PM
huh? what would that do? If you really wanna do something wrong and install a BOV in your car it would just go where the stock DV is. But it will make your car run rich. Why would you want to relocate the MAF? what would that accomplish?

if you were to relocate the maf to say turbo to intercooler pipe, you would no longer be dumping unmetered air ;)

sean1.8t
08-06-2007, 04:35 PM
just wondering if anyone here has relocated thier maf so they could run a bov...is that possible? i am thinking bout a custom fmic and thats somthing i might want to look into.


Why would you want to relocate the MAF? what would that accomplish?

what you are talking about is a blow thru MAF. it is common on many other turbo'd cars. such as WRX/STi's. it is where you run a MAF after the intercooler and right before the throttle body. this way you are able to dump the air using a BOV and not have to worry about running rich or anything. it also cuts down on headaches such as stuffing a MAF and cone filter in the small area our cars allow for an intake

dualaudi
08-06-2007, 06:43 PM
what you are talking about is a blow thru MAF. it is common on many other turbo'd cars. such as WRX/STi's. it is where you run a MAF after the intercooler and right before the throttle body. this way you are able to dump the air using a BOV and not have to worry about running rich or anything. it also cuts down on headaches such as stuffing a MAF and cone filter in the small area our cars allow for an intake

I was wondering the same thing when i first put my BOV on... have you or anyone else ever run with the MAF moved over toward the intake manifold? it's almost seems to easy to do to be correct...

dualaudi
08-06-2007, 06:44 PM
you want a diverter valve not a BOV. ive heard bad stories about BOVS

What kind of bad stories?

ILoveT
08-06-2007, 06:53 PM
As long as you run a recirc kit you are fine.

And could you just move the maf just before the TB?

Audi91a4
08-06-2007, 07:02 PM
X2 I also want to know if its possible to run a blow thru MAF

mike-2ptzero
08-06-2007, 07:40 PM
You guys do understand that most maf's work by heating up a element which is then cooled by the air flowing past it, this is how it figures out how much air flow there is. The big problem with placing it after the turbo is the fact that the air is now going to be much hotter then it was before the turbo.

daesharacor
08-06-2007, 08:16 PM
... haha end of discussion. Thanks, someone should have piped up with that awhile ago :-P

ILoveT
08-06-2007, 08:23 PM
Wow, what was the point in saying that? "Thanks" Thanks for what?

tunerb5
08-06-2007, 10:16 PM
I have my Forge 004 BOV relocated right before the TB.

GramCracker
08-06-2007, 10:32 PM
why not just use a hybrid dv/bov? this way you dont have to change shit.

daesharacor
08-07-2007, 05:28 AM
Wow, what was the point in saying that? "Thanks" Thanks for what?

Because I wasn't sure how a maf measured air flow, and now I know. Also explains why it can't be downstream of the turbo which explains why bov's can't be run without a recirculation kit or wicked a/f problems.

daesharacor
08-07-2007, 05:57 AM
You guys do understand that most maf's work by heating up a element which is then cooled by the air flowing past it, this is how it figures out how much air flow there is. The big problem with placing it after the turbo is the fact that the air is now going to be much hotter then it was before the turbo.

Mike - Just out of sheer curiosity, what if... the ambient air temp sensor was relocated inside right next to the maf (somehow)? This would correct for the reduced cooling effect from the warmer air, right? I'm assuming the maf uses the ambient temp sensor to calculate the flow rate... it would have to, right? And if the ambient sensor is somehow reading post-turbo temps, it would be accurate, theoretically.

Or if some awesome electronics guru could figure out a way to get the maf to listen to the iat sensor instead.

Thoughts?

daesharacor
08-07-2007, 06:45 AM
Apologies for the multiple posts, but I'm at work and I need to waste time by doing research like this, right?

I emailed my dad about what he thought, and this is what I got (about my theory of relocating the ambient sensor) -


I know that the MAF sensor is "sensitive". A bit of oil (from an over oiled K&N for example) will ruin it. I had to have one replaced under warrantee on the vdub. Since I heard that I took out the K&N for the vdub which I had installed just in case.
The MAF is pricey too. I don't think it was designed to be used with hot
compressed air that may or may not have a bit of turbo oil or other types of contaminants in it. I think that you are right about the theory of operation. Don't know if it's response would be proper with 20 psi air that is much warmer than ambient even with AAS modified. I would leave it alone for the time being. There is no performance increase and only hassles. As for the sound.....whoosht thing. Program it into your Ipod and play it when you shift?

Haha, so nuts to my theory. Oh well.

Don Supreme
08-07-2007, 07:08 AM
I have my Forge 004 BOV relocated right before the TB.

x2

mike-2ptzero
08-07-2007, 07:10 AM
Apologies for the multiple posts, but I'm at work and I need to waste time by doing research like this, right?

I emailed my dad about what he thought, and this is what I got (about my theory of relocating the ambient sensor) -



Haha, so nuts to my theory. Oh well.


Also remember that the crank case breather blows back into the intake take track too, which means more oil vapor/oil will end up on a maf that is after the turbo.


BTW the sensor that the ecu uses for reading air temps(IAT sensor) is mounted just after the throttle body in the intake manifold.

AudiA4_20T
08-07-2007, 07:29 AM
huh? what would that do? If you really wanna do something wrong and install a BOV in your car it would just go where the stock DV is. But it will make your car run rich. Why would you want to relocate the MAF? what would that accomplish?

lol poor Spencer doesn't understand whats going on

TMorris
08-07-2007, 10:53 AM
As for the sound.....whoosht thing. Program it into your Ipod and play it when you shift?




Haha that sounds like my dad

_audible_
08-07-2007, 11:13 AM
You have a cool dad.

daesharacor
08-07-2007, 11:45 AM
haha yeah I know, he's one of those really knowledgable guys about the old-school tuning... 2 stroke motorcycle racer back in the day, lifelong engineer, the classic wrench-head who'd rather disassemble a transmission than disassemble a computer... almost the opposite of me, oddly enough. I like all the clean, new parts, easy installations, not much patience, he's the "get-out-the-torch-and-pbBlaster-and-lets-do-this!" kinda guy. Good resource when learning cars myself.

xr4tic
08-07-2007, 12:29 PM
Yeah, you guys are right, it would never work.

Oh wait.

It does.

http://johnbaas.dyndns.org/2point0/maf_bosch_blow_lo.jpg

It's an old picture, and was my initial test install, so ignore the mess, it looks different now with the VR6 TB and ford 3" MAF

I did it for 2 reasons:

1) BOV post-IC I don't give a f---, call me what you want, I like it.

2) easier to plumb the MAF in there, than in front of the turbo (T3/T4)


The MAF could care less where it's placed (as long as it's a sealed system) - it measures density, it's a lot more complicated than a simple temp sensor.

daesharacor
08-07-2007, 12:46 PM
wow, nice. You've never had any fouling problems with the maf? Looks good, if I had the balls and knowledge and money for eff-ups I'd do the same. I like the bov sound, so sue me. :-P

ILoveT
08-07-2007, 01:07 PM
Hell Fuckin yeah!

mike-2ptzero
08-07-2007, 01:09 PM
Yeah, you guys are right, it would never work.

Oh wait.

It does.

http://johnbaas.dyndns.org/2point0/maf_bosch_blow_lo.jpg

It's an old picture, and was my initial test install, so ignore the mess, it looks different now with the VR6 TB and ford 3" MAF

I did it for 2 reasons:

1) BOV post-IC I don't give a f---, call me what you want, I like it.

2) easier to plumb the MAF in there, than in front of the turbo (T3/T4)


The MAF could care less where it's placed (as long as it's a sealed system) - it measures density, it's a lot more complicated than a simple temp sensor.



Its not that it "cant" work, it just doesn't work all that great because of how our maf works. Plus doesn't the ndbw maf have measure air temps?


Now the question would be. How well did your car run with the stock maf in that spot?

Pretty sure you also run a catch can which would have to be used when running the maf in that spot.

Militant-Grunt
08-07-2007, 01:18 PM
Its not that it "cant" work, it just doesn't work all that great because of how our maf works. Plus doesn't the ndbw maf have measure air temps?


Now the question would be. How well did your car run with the stock maf in that spot?

Pretty sure you also run a catch can which would have to be used when running the maf in that spot.

I started reading the thread earlier in the day, and was going to post that all this speculation is making me want to try this. But that picture is just icing on the cake, still laughing. Any problems with the MAF on that setup?

xr4tic
08-09-2007, 10:02 PM
Its not that it "cant" work, it just doesn't work all that great because of how our maf works. Plus doesn't the ndbw maf have measure air temps?

Now the question would be. How well did your car run with the stock maf in that spot?

Pretty sure you also run a catch can which would have to be used when running the maf in that spot.

the NDBW MAF does not measure air temps, it's only 4 wires.

Funny thing is, the car ran the best in this config, with the stock MAF in 3" housing with PES T28 chip (because that's what it was tuned for) Then I started messing with different setups because it wasn't optimum for my car.

Yes, you would have to remove the crankcase vent from going into the intake manifold, but I see that as a plus - less chance for oil to come in. You also need to keep a straight section in front and behind the MAF, I would say at least 6", and the more the better.

The only downfall I can see is that the higher heat the MAF sees could be more likely to burn out a weak MAF

Just keep in mind that my car is far from stock, so what works for me, may not work for everyone else.