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Old 03-07-2000, 09:24 AM   #1
Scooby Specialist
Member#: 102
Join Date: Jul 1999
Location: The meeting place
Question The need for an SAFC

OK, it seemed like a few months ago, we were going thru a UR plley fad. Not it's the SAFC fad. I would like to know on an N/A car, how it would increase the performance and does it do specifically. It seems like owners just buy them and dial in the settings and go. There's no mention of why it's needed.
1) To control lean and rich mix?
2) I have a K&N filtercharger and a custom exhaust. Should I top it with an SAFC to get the max performance?
3) Is it more like safety measure than a performance mod? Any gains?
4) I noticed some owners claimed more power up end?
5)Will I lose gas mileage?
6) Is Apexi the only brand?
7) Can I get fries with it?
8) will t modify my Playstation as well?

This SAFC thing needs an FAQ! I did a search and virtually every post came back cu it seemed like everyone has one?!
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Old 03-07-2000, 10:12 AM   #2
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Member#: 137
Join Date: Aug 1999
Location: Ft. Worth, Tx. US
Thumbs up

You're right it does seem like a fad right now, b/c of what Shiv has figured out. See awhile ago, people who bought an intake noticed that there was a flat spot in the rev range around 4k-5k rpm, so they bought the FPR.
FPR: Fuel Pressure Riser, from Weapon R.
This is pretty much the same device, except it's mechanical(always on). The AFC is a computer and you can specify how much more fuel and at what RPM. This computer also helps when the N/A turns Turbo. As far as the other questions go: Gas mileage shouldn't change that much, and I don't think Apexi is the only company that sells them. How 'bout Onion Rings.

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Old 03-07-2000, 11:01 AM   #3
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Join Date: Jul 1999
Chapter/Region: BAIC
Location: Pleasanton, Ca
2009 WRX Wagon


The whole reason for having an AFC is to counteract the lean condition that occures with custom intake piping. The lean condition is a result of inaccurate MAF readings, which lead to a relativaly low air flow reading. blah blah blah. If you don't have a lean condition, ala custom intake, then there probably is no point to the AFC. Of course someone will disagree with me, which is fine as long as they give a good reason why you need one.

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Old 03-07-2000, 02:02 PM   #4
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Join Date: Jul 1999
Location: The meeting place

How do you know you're running rich or lean?
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Old 03-07-2000, 05:33 PM   #5
Bret Jensen

Gambit - you need at least an Air-to-Fuel Ratio (AFR) meter, and it's even better if you also have an Exhaust Gas Temperature (EGT) gauge. These allow you to determine the richness or leanness of the mixture.

Making modifications to the intake, exhaust, engine, etc. will alter the AFR somewhat. Sometimes the changes are severe enough in the lean direction to key the knock sensor. This will result in timing retard and your RS will feel sluggish at that point. On the other hand, mods can also make your engine run richer. There's no point in running any richer than you need to, as it wastes fuel, can damage your catalytic converter, and can reduce your peak HP.

In my RS I find that the car runs noticibly smoother in 4th and 5th gear with +2 at 1000, +4 at 2000, +2 at 3000, and zeros for 4000, 5000, 6000, and 7000. This was especially apparent in the recent warm weather (hot ambient temperatures lower the knock threshold, as does increasing the engine's load with the compressor).

I will say that a small shortcoming of the fuel controllers is that they don't take into account what gear you're in. With all zeros in fifth my O<sub>2</sub> voltage will hit a low of .84 at 2500 and a high of .88 at 4500. In second I'll get .87 at 2500 and .92 at 4500. For this reason I use a different setting for driving around town, one which has some minuses.
Old 03-07-2000, 05:40 PM   #6
Bret Jensen

Oh, to answer some of your questions...

4) I noticed some owners claimed more power [on the top] end?

You'll make your peak power when you are running an optimum AFR. If your AFR is not optimum, you can get more power by making it so.

5) Will I lose gas mileage?

Yes, from WOTing to see what your changes are doing . Actually it depends on your settings. When it's cold I can run -2 at 3000 and 4000 RPM. On a long freeway drive this might add up, but I haven't had a chance to try and break my record [29.2 mpg] without the controller yet.

6) Is Apex'i the only brand?

No, I have a Field Hyper-R SFC. In my opinion the Apex'i is overkill on a normally aspirated engine, but others differ. The main difference in functionality is that the Apex'i allows each program to have different settings at heavy, partial, and no (i.e. decelerating) throttle. This is useful if you have a turbo and your boost pressure is varying with your throttle position. In terms of cosmetics, the Apex'i looks cooler.
Old 03-08-2000, 01:25 AM   #7
HRE | giulio
Former Vendor
Member#: 481
Join Date: Nov 1999
Location: NY USA

also, 98 and 00(i think) run rich at the top rpm range. I use it to lean the mixtrue back to optimum and get a few more horses out. it's not BS, i really feel the difference.
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Old 09-17-2000, 09:50 AM   #8
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Join Date: Dec 1999
Location: Windsor, Ontario CANADA

So who manufactures EGTs and AF meters (assuming one doesn't want to use the Apexi "blue wire mod") and how exactly does the O2 reading of .85v, .87v, .90v correlate with lean and rich conditions?
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Old 09-17-2000, 04:57 PM   #9
JP Money
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Join Date: Feb 2000
Location: Auburn Hills, MI, USA

Whoa dude.. you really dug this one up.. Although I would like to know that too

I have an A/F gauge from Autometer. It reads two bars to the lean side cause its hooked up to the second 02 sensor. I dont know about the voltage stuff
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Old 09-17-2000, 07:23 PM   #10
Scooby Specialist
Member#: 660
Join Date: Dec 1999
Location: Windsor, Ontario CANADA

I've read so many "new" posts about stuff that already has a thread....I'm a firm believer of Searching. Anyone wanna comment on the voltage readings?!?!?!
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