VAF on 2nd gen B6

[scitzz]

I did my B6 swap using a second gen B6 from a 1992 Mazda 323. At Madness, Artie told me I should have replaced my VAF as well. I am getting ready to hit the local LKQ, and am wondering what VAF I can use, if any, other than from the second gen, 92-94 323?

[Damkid]

Dude the VAF's are able to be tweaked, I know a guy running a BPT with a stock BP ECU and a tuned RX7 VAF and that's it, so if you gas mileage is where it should be, I say leave it alone and save your money

[gauge_half_inch]

Early Kia Sephia (pre 98 ) also had the same b6 in them. That's actually where I got my first one from. As long as its the "s" code your good to go.

[scitzz]

Damkid, my gas mileage is abysmal right now.
gauge, S code?

[Damkid]

Abysmal??

If you look on any VAF, there's a letter on it, "S" would be for the B6 then

[gauge_half_inch]

Yep. S

[FestYboy]

yeah Paul, what happened to the MPG?

[Advancedynamix]

I think he is still running the b3 vaf IIRC. Paul, what does that word mean? Is your mileage bad?

[FestYboy]

abysmal: horrible, bad, sucky, crappy, poopy, etc.

[Advancedynamix]

Ah, that makes sense with the "abs" root.

Anyway, it's possible the b3 vaf actually causes the car to run rich with the b6 injectors. If the flapper goes wide open earlier than a b6 unit and the ECU is trying to deliver fuel as though it had smaller injectors the injector dwell could be too long, especially at wot when the system is open loop.

[Festiva_Fred]

Wonder if that's why my B8 car has only hit a max of 35 mpg or so... it has a K code vaf, which isn't a B8 vaf I believe. I'd like to see better mileage out of it, 40's would be nice, and I hit that max mpg driving it very easy.

[iceracerdude]

I did my B6 swap using a second gen B6 from a 1992 Mazda 323. At Madness, Artie told me I should have replaced my VAF as well. I am getting ready to hit the local LKQ, and am wondering what VAF I can use, if any, other than from the second gen, 92-94 323?

Look what I have:


If you are interested or don't find one at the LKQ drop me a line.

[blkfordsedan]

So what exactly is the difference between the VAfs? I'm familiar with MAFs, and I know they need to be calibrated to the injector size, so is the VAFS the same? Is it as Charlie described? Just a function of air volume displacing movement on a door...so the doors have differing surface area? I am very nervous about having a modded b6 and concerned about not being able to tune it for max potential. I'm a little spoiled with the OBD2 of my Mustang and being able to use a handheld or laptop.

[Advancedynamix]

no need to be afraid of VAF's. They are outdated in comparison to MAF, but what is nice is that there are lots of options for our cars (Denso only made a few different configurations of VAF and most are to some degree interchangeable with very little work). Also, unlike a MAF, a VAF is adjustable. Just pop that black cover off and there is a spring tension adjustment. It can be used to fine tune for different flow injectors, fuel pressure, boost, you name it. You can also drill hole in the flapper door to change the characteristics of the unit, but don't do this unless you have a few spares because it's a trial and error mod for sure.
Early Non OBD compliant fuel management systems are very tunable if you know what to play with. VAF, FPR, Injectors and ignition curves are all variables that can be altered by a regular Joe and with Harbor freight tools and salvage yard parts. It's actually a lot of fun when you get used to it. Less messy than carburetors and points, and more hands on than OBD2 tuning software.

[scitzz]

Sorry to take so long getting back, the LKQ trip was an adventure with no end. To top it off, the house has been a dreary place, my wifes friend from childhood passed today. I never got to know her, but wifey has been grief stricken

Anywho, yeah, the untouched 323 that was out there a couple weeks ago is GONE. So I might take you up on that VAF, Ice, how much?

Charlie, Arty, when I saw you guys at Madness, I was getting 19.5 to 20MPG. Then, with the new gasket on the TB, the "fix" on the IAC, and the increase to 40PSI on the tires, I started getting 23.5 MPG. I put in a tank of 89 and worked a night, and then went to Raleigh today. At tank up, I got 22.34 MPG, including some highway, but also 20 miles towing 600 pounds of steel.

That whole running rich thing. I think you are on to something, I have noticed some things, like it backfired the other night when I missed my shift, and went to fourth instead of second. How exactly do you know when you have it tuned right? Other than trial and error?

I had hoped to change that IAC out tonight. I have been soaking it in MMO, or sometimes PB Blaster, since Madness. It still seems to not be operating. I turn on my lights, and I drop to 650, and never come back up in RPMS at least. Doesn't seem to be in the cards, perhaps Monday.

Thanks for the help so far!