Safc

[wiccanferret]

Any idea how much one of these would benefit a 3100V6? Can anyone give a quick rundown on what, exactly, they do?

[Gimli]

Can you tell us what, exactly, they are? :)

[Matt95GT]

Piggyback engine tuning device.
Intercepts MAF signal (or MAP, depends on your engine) and allows you to add/subtract fuel from you air/fuel curve in order to tune your engine.

http://www.apexi-usa.com/electronics_safc.asp

This is no toy, it will empower you to make adjustments that could potentially blow your engine. I would recommend against it unless you will be running boost/Nitrous or have massive amounts of engine work. An average NA engine with intake/exhaust/etc will not benefit from it.

[wiccanferret]

Yeah, but for $250 on ebay, even .2-.3 secs at the track would make it worth the cost. They're not very expensive for what they do. I'm wondering HOW it makes the adjustments and how it's installed.

[Matt95GT]

Originally posted by wiccanferret
Yeah, but for $250 on ebay, even .2-.3 secs at the track would make it worth the cost. They're not very expensive for what they do. I'm wondering HOW it makes the adjustments and how it's installed.

This is only a tuning tool... only a small piece of the puzzle. IT doesn't tune your car, YOU do... using either wideband O2 meter or exhaust gas temp gauge while on a chassis dyno. Specificly, you set + or - fuel percent on a few points of the RPM curve (1 for low throttle, 1 for high) and the S-AFC interpolates in between. Also, on most GM applications those who go boost also need FPR/FMU to adjust fuel pressure, and different injector sizes. Ultimately, the FPR/FMU adjustment will control the rough amount of fuel injected, while the S-AFC is used to make fine adjustments to the air/fuel ratio (by adding more or less injector pulse).


To answer how it actually does this and installation...
-It taps into various engine sensors used by the PCM... tach, TPS.
-MAP (or MAF) return line is cut. MAP sensor output now goes to the input of S-AFC instead of the PCM. S-AFC output goes to PCM MAP input.

Since the S-AFC is inline, it can modify the MAP signal the PCM uses to determine how much fuel to inject.

As I said before, there will not be any difference on a stock/light-mid modded engine. The stock PCM can adjust for a great number of mods that would increase air flow. This device (and other fuel mods) would only be needed once the parameters of the stock PCM tables are exceeded. In other words, the PCM is already adjusting for you mods, and adding the S-AFC is pointless because there is nothing to adjust for... unless you want to be extra rich (slower and fails emissions) or lean (detenation - engine go kaboom)

BTW - S-AFC is cheap on ebay cause S-AFC II is now out.

[wiccanferret]

Actually the SAFC2 is what I saw for around $250. But if it just manipulates sensor signals, then I can see how it would not help a close to stock car in most cases. Thanks for the info! :)

[CARS GONE WILD]

doesn't running richer make u faster?

[DomestikDemon]

too a point, then you just waste fuel....like matt said....without boost, these are pointless

[Matt95GT]

Holy old thread batman... heh my other posts were before I actually had an S-AFCII also, which I recommend for boosted 2.3's.

Originally posted by CARS GONE WILD
doesn't running richer make u faster?

No... too rich will actually cause a performance loss. When it comes to typical bolt-ons on a N/A engine, leave the stock tuning alone or use a "pre-tuned" reprogramed PCM (if available for your application) since they will help in the form of ignition timing advance as well.