View Full Version : Better AFM?

08-26-2010, 10:05 PM
Hey guys, this will probably be my first major mod to the all trac. i was just wondering if there were any AFMs that were perhaps bigger or that would basically work with the stock 3sgte ecu? i read up on the MAF vs. MAP argument and i believe that the MAF based system is better for changing turbo sizes and such. so i was basically wondering if there was an AFM from like a supra or something that was bigger and could be wired up to the 3sgte and had a similar voltage scale (0v wide open-4.6v closed).

thanks for your help.

08-26-2010, 10:51 PM
Nope. The only other AFM I can think of thats backwards like ours is an RX7 one. The rest of em are 0-5v like they SHOULD be.

08-26-2010, 11:12 PM
what generation rx7?

08-26-2010, 11:31 PM
the problem with AFM is that its calibrated for the size pipes and what the ECU wants to see. and sorry speed density is the way easier way to tune when making big changes like turbos.

but if you are using a standalone EMS and want to stay AFM then i would suggest upgrading to something like the Subaru STI MAF like we do in the 7th gen celica. its still a 0-5V but has a much larger scale

08-27-2010, 04:56 AM
what generation rx7?

86-88 non turbo RX7. NipponDenso Part #17100-3250

08-27-2010, 05:01 AM
just go with a stand a lone ems or if you want to do some research on upgrading to a gen 3 electronics, it uses MAP.

joe's gt
08-27-2010, 06:28 AM
A change in turbo would need to be optimized by a re-tune anyway. Speed density helps compensate for minor changes in VE (ie: a vacuum leak) but measurement of airflow does generally respond better to more major modifications. But a turbo change is beyond major and should be accompanied by a re-tune whether speed density or AFM.

08-28-2010, 02:04 AM
86-88 non turbo RX7. NipponDenso Part #17100-3250

If you're interested in this, see the "Useful Knowledge" subsection in this forum. I posted an article up about just this thing a few days ago.

08-28-2010, 05:43 AM
Mike, if you keep on doing all of that work you're going to wind up with a job, lol.

08-28-2010, 06:13 AM

the captain showed me this link. one of the awesome things that this thing does is deletes the MAF entirely :) enjoy

08-28-2010, 06:24 AM
That is a must have. Thanks for the link.

08-28-2010, 07:41 AM
no problem :thumbsup:

if only i could afford it right now. as soon as i sell my old rims i surely will be able to. anyone want some 4lug rims in the bay area? :)

08-28-2010, 10:01 PM
I hadn't seen that before. That's a really neat set up. I'm going to have to check into that.

09-01-2010, 06:52 PM
it's possible if' you're willing to do a little legwork.

any 0-5V MAF sensor can be made to work with an inverter circuit to switch it over to 5-0V, and then use an AFC or some other "tuner" module to tweak the voltage curve. the UAFC over on 14point7.com (http://14point7.com/UAFC.php) would likely work well for this, and isn't terribly expensive. that + a ford MAF sensor would cost only a little more than a used AFM for our cars. i had always meant to datalog the stock AFM signal vs. airflow but i never got around to it.

09-01-2010, 08:20 PM
OFF TOPIC: Mike, congrats on your new pink status! :)

ON TOPIC: I've been thinking about doing the 3rd gen conversion for some time now.... It's going to be interesting on Nyx's car though, st165 with a built st185 motor running st205 electronics? hmmmm....

09-01-2010, 09:40 PM
Changing the AFM is probably not a good "1st" mod. Really, the stock AFM is fine until you start to want a new ECU. Switching them out for an RX7 one for example, is just going to place you on load cells that the ECU is not designed for...could make you really lean and/or really aggressive on timing, or the opposite. Or it could be close to right. Really hard to say. Either way, there are better places to spend your time.

On that note however, as an AFM to MAP convert, I'd say once you try it, you'd never go back.

09-05-2010, 03:28 PM
yea i'm getting to want a map every day more and more. the slightest vacuum leak is giving my car a heart attack. plus all that cold start crap. oh well MAPECU is probably my best option. it's just finding someone to tune it

09-05-2010, 04:46 PM
I'm having the same problem, I have a leak somewhere that popped up recently and its seriously pissing me off. I can't put the pedal to the metal without a huge lag. It'll go, but then it'll basically start vibrating and sound like its prematurely exploding...which is the wierdest thing. Ill post a video of what it sounds like when I drive it. Not sure how the sound qualitys going to come out though, since I'm in the middle of exhaust work and it running only one cat (in the DP) :p and its intensely loud. What did you mean by "and all the cold start up crap"? Bad cold start injector?

Not sure what's wrong with my 185, because when I start it, it'll either idle around 1,000, 2000 or 3,000...depending on what it wants...ehh.

I just scrounged up the money to get my mapecu. I have enough to get the regular 400 dollar mapecu, but it doesn't really explain the difference between the 700 dollar mapecu 2... so I'm gonna read up about it more before I decide which one to get. And yes, finding someone to tune it will be a pita. Unless if I tune it myself. :) id rather spend a couple days tuning it myself as opposed to a couple hundred to get it tuned. I'm a big DIY guy, what can I say? :p

09-10-2010, 08:57 AM
There is a better way to swap out to a "real" 0-5V MAF..... My partner and I were working on a really simple kit to do it, but the business disolved and the product (while showing HUGE GAINS) went the way with the rest of the business.

Pick up any 0-5V maf that can be fit in line with the intake. We used one from a Mustang Cobra. we then used a split second PSC1-005 AFM to MAF conversion signal calibrator.

Pretty easy, and gives you tune-ability.