[dustylax]

anyone wanna check if the new 2.5 wrx uses the same maf, i have one of these and never tried putting it in since i was told ours and the sti were the same, but i see now the part number is different than what i was told previously so i will try it eventually, should be some good potential for it if you can make 400whp no problem on the sti w/it.

 

[turbo_jimbo]

it would make sense since toyota owns the majority of subaru now...

 

[FriendOfSpyder]

opcorn: :flame:

 

[dustylax]

i never understood the popcorn icon

 

[FriendOfSpyder]

really? Its means i'm gonna hang around and look into this tread some more- whats a better 'chillin' food then popcorn!

 

[WTS]

Yea, but opcorn: + :flame: =

 

[FriendOfSpyder]

what has this site come to :roll:

 

[Tem]

Originally posted by Jesse IL
As far as re-tuning for this MAFS, technically there shouldn't be really that much you need to do. The airflow curve should simply be sfifted by a straight percentage compared with the stock sensor. What you should be able to do is take a log at idle, once you get a steady idle that is and your MAFS voltage stabilizes. Since there will be slight fluctuation, just take an average value over time.

Next, pop in the STi MAFS and do the same thing. It will drop to a lower load cell since its reading less airflow, but you know that it has to be flowing the same amount of air since you're running the same rpm. Just bring in a bit of fuel to bring the AFR up to where you were and again, look at your average voltage.

You take V1/V2 and you'll get a number a bit greater than one. Then you just take the whole airflow curve, multiple every cell by the number you just got and paste it into Option 2 or wherever you want. Car should run exactly the same.

Did you try this? Did it work?

Seems like the Subaru MAF and our MAF don't have the same airflow/voltage curve. Get it right at one point and it's off elsewhere, if done like you said. :?

I don't have the stock sized pipe anymore though, so I wonder if that makes a difference..?

I was wondering if I run both MAFs at a same time, running the PFC from the stock MAF and just datalogging the voltage from the Subaru MAF. They both would flow the same air at a same time, right? And should be easy to get the curve for the Subaru MAF through that, right?


Also, anyone know the engine codes for the Subarus with these MAFs? Or more importantly, is there a PFC version for these?

 

[Kevin Beane]

Originally posted by Tem
I was wondering if I run both MAFs at a same time, running the PFC from the stock MAF and just datalogging the voltage from the Subaru MAF. They both would flow the same air at a same time, right? And should be easy to get the curve for the Subaru MAF through that, right?

Sheer genius. All you need is a tube with two MAF mounts.

 

[FriendOfSpyder]

the intake piping diameter will have a big affect on the MAF.


So still not 100% confirmed if this Subi MAF is indeed different?

 

[Tikked]

Originally posted by FriendOfSpyder
the intake piping diameter will have a big affect on the MAF.


So still not 100% confirmed if this Subi MAF is indeed different?

I'll be putting mine in next weekend. I can data log the pre-subi maf voltage with the Profec to verfiy but I'm sure it will be a very noticable difference if it works.

 

[FriendOfSpyder]

cool, i will also be playing around with this next weekend as the week after is dyno day for me, so i'm stoaked, but gotta have a few options...

Joe

 

[dustylax]

well the maf is waiting for you joey so just give me a day and we'll do it.

 

[Tem]

Originally posted by FriendOfSpyder
the intake piping diameter will have a big affect on the MAF.

So still not 100% confirmed if this Subi MAF is indeed different?

It's different for sure. No idea about how much (if any

) further it goes than ours though.


Oh and I was trying to ask if the intake piping diameter makes the air flow curve change shape? I know it rescales the curve, but from Jesse's post I understood that they should both be linear, having x% difference across the whole range.

 

[dustylax]

yes, it will def bring it further, granted its a different engine/size/turbo, but you can squeeze almost 450whp out of an sti still using the stock maf in a 3 inch pipe, so that should be good for most people on here w/o needing to change to hydra for the map sensor.

 

[FriendOfSpyder]

Dustin, lets get together friday after work....

I'm very skeptical

I have to bleed the coolant and finish with the oil cooler, but friday might look good!

call me when you get a chance

Joe

 

[dustylax]

i will try and be home when your done friday, you could be out here at like 7ish ? i'll see whats going on and see if thats def. doable, call you in a few.

 

[Curt]

Hey guys, I'm on a fast-track learning curve here and headed towards a Rotrex setup, so any of you who have expert knowledge on this subject, please critique the following interpretation I have of the effect of changing the size of the MAF tube:

If you took the stock Spyder MAF and put it into a larger tube, for any given RPM and load the intake air going past the "hot wire" would be moving slower (than it would have in the original, smaller tube), thus having less of a cooling effect on the hot wire, and thus requiring the ECU to send less voltage to the MAF to maintain the temperature of the hot wire. If that's the case, seems to me the result would be a leaning out, and you'd have to make adjustments in the PFC to recalibrate the relationship between the voltage curve and the mass of air. If the stock MAF has an upper limit of 5.0V (if I understand this correctly), that should mean that with a PFC corrected for the larger tube you wouldn't max out the stock MAF as early when going forced induction.

If the above is correct, then (1) a larger MAF tube, or (2) the STI MAF, or better yet (3) both together will raise the limits of the stock MAF for the mass of intake air it can pass and accurately measure. And thanks to LR and the guys over on NC.org for the heads-up about the Subaru MAF.

 

[oilfield_trash]

<div class='quotetop'>QUOTE (Curt @ Aug 5 2007, 06:03 AM) <{POST_SNAPBACK}></div>

Hey guys, I'm on a fast-track learning curve here and headed towards a Rotrex setup, so any of you who have expert knowledge on this subject, please critique the following interpretation I have of the effect of changing the size of the MAF tube:

If you took the stock Spyder MAF and put it into a larger tube, for any given RPM and load the intake air going past the "hot wire" would be moving slower (than it would have in the original, smaller tube), thus having less of a cooling effect on the hot wire, and thus requiring the ECU to send less voltage to the MAF to maintain the temperature of the hot wire. If that's the case, seems to me the result would be a leaning out, and you'd have to make adjustments in the PFC to recalibrate the relationship between the voltage curve and the mass of air. If the stock MAF has an upper limit of 5.0V (if I understand this correctly), that should mean that with a PFC corrected for the larger tube you wouldn't max out the stock MAF as early when going forced induction.

If the above is correct, then (1) a larger MAF tube, or (2) the STI MAF, or better yet (3) both together will raise the limits of the stock MAF for the mass of intake air it can pass and accurately measure. And thanks to LR and the guys over on NC.org for the heads-up about the Subaru MAF.[/b]

You've got the idea.

 

[Tem]

<div class='quotetop'>QUOTE (Curt @ Aug 5 2007, 02:03 PM) <{POST_SNAPBACK}></div>

If the above is correct, then (1) a larger MAF tube, or (2) the STI MAF, or better yet (3) both together will raise the limits of the stock MAF for the mass of intake air it can pass and accurately measure.[/b]

I've gone through (1) to (3). Stock MAF in a bigger pipe sure gave you more range, but it also seemed to make the low end less accurate. The Subaru MAF in the same bigger pipe gave even more range, but also seemed to keep the low end very accurate. Kinda like it was meant for a larger pipe. (maybe it is, I have no idea about the Subaru pipe size) Anyway, I've never had this stable and low idle. Not to mention I can floor it on 5th and it just starts to go. 8)
(where's the cool/sunglasses-smiley?)

Btw, seems just about every new Subaru has the same MAF, at least over here. It's not really STI/WRX MAF, just a Subaru MAF. Even the N/A models have the same MAF.


And since we're on the topic, Denso makes many other "identical" MAF's, it's not just the Subaru one that gives more range. One of them is from Toyota Altezza, Denso part number 197400-2000, Toyota part number 22204-21010. No idea about prizes in US, nor which gives most range.