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Old 07-16-2002, 01:29 AM   #1
BMW Man in 2.5RS
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Default s-afc 01 RS

ok someone please explain to me why the afc does not work on my car. For the past year or two that ive been on here every thread on this people say it only works on the 97-99 rs's but why doesnt it work on my car. Ive done a search and came up with nothing. I know people say that the ecu will relearn but the AFC signal comes after the ecu signal so i dont understand this. could someone please explain. Thanks...Joe
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Old 07-16-2002, 02:18 AM   #2
quicksilver
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There's an old post out there somewhere, I think it was started by Longshot, that might give you the info. you want. If I remember correctly, he did several dyno runs with different settings and gained about 4 h.p. at the wheels with it. As for the ECU learning over the S-AFC, I don't think anyone is exactly sure if it will or not.

-Mike
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Old 07-16-2002, 11:15 AM   #3
MY99 2.5GT
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The SAFC will work for your car.

The stock ECU only learns around your SAFC settings when your not in Open Loop Mode(WOT). When you jam the go pedal (WOT-wide open throttle) your ECU reverts to whats called Open Loop Mode. In this mode the ECU uses set fuel and ignition maps and readings from only a few sensors to give you the maximum power available. In this mode the ecu learns nothing. Thats why it is beneficial to have an SAFC to tune Fuel mixture for the aftermarket mods you have.

When your cruising around town without the pedal to the metal the ECU stays in Closed Loop mode. In this mode the ECU takes readings from a bunch of different sensors and thinks about those readings and calibrates fuel mixture and ignition timing for best gas mileage.

This is a great thing for your modded RS. You can program the best fuel mixture for making max power with your mods at WOT (When your racing or just have a desire to see how the car performs) while saving you on gas milage during your around town driving.

Brad
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Old 07-16-2002, 11:17 AM   #4
phucvtec
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I have ben wrestling with this question for about a half a year now. I always read any post about the S-AFC with hopes of getting more insight. Basically, what ive taken away from most of the discussions is that your vehicle's stock ecu is very good at learning your vehicle's performance characteristics quickly after you perform a mod, such as a cat back exhaust or a CAI. However, it is also pretty well agreed on that even after the ecu reprogram available for about half of the 2000 models sold, you can expect your vehicle to still run rich. I also have found from experience that your vehicle will run progressivly more rich as you start bolting on mods. I have to believe that this is sort of a fail safe developed by the manufacturers so that in the event of (1) a mod, or (2) a failure of part of your intake or exhaust, your ecu automatically runs the vehicle rich so that there is no chance of leaning out. So... for the S-AFC... this is my feeling: If you plan to set your S-AFC to perform corrections during normal opperating conditions (idle, cruising, casual driving and whatnot), eventually the vehicle ecu will "learn" and recorrect to compensate for what you have done with the S-AFC. However, if you only have the S-AFC perform corrections when your beating the crap out of your vehcile (probably about <1% of the time), you can effectivly lean out the mixture and get a little more power out of your engine. I do this, and I am very satisfied. Not to mention, the S-AFC provides you with real time monitering tools for various sensors, which is nice. Hope this helps, and please correct me if im wrong
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Old 07-16-2002, 11:20 AM   #5
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Very simply, Brad has said it much better than I ever could have. (he posted while I was posting )
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Old 07-16-2002, 11:52 PM   #6
DangeRS
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well i heard this, the reason why the safc wont work is because of the voltage of the map sensor being to low or to high..also couldny you just disconnect the battery every now and then so reset the ecu so teh safc readins will still eb the same, making it the same as once you set it in the first place on the safc?
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Old 07-17-2002, 12:52 AM   #7
BMW Man in 2.5RS
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alright becuase id like to put one on my car cuz i can think of many advantages to them. I would prob take it a dyno with a wideban o2 sensor and tune it out all motor with the mods i have now. If what your saying about it working only at wot that would be perfect. One thing though i am wondering does anyone have the conversion chart for 02 sensor volatages so i can figure out my A/F ratio so i can do some preliminary tuning from my pocket logger. Thanks...Joe
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Old 08-01-2002, 11:57 AM   #8
DangeRS
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ok ok, i know its been talked about. But somone definatly told me the safc will nto work on a map sensor because of the voltage reading.. it will not be able to read the map sensor makign your corrrections on teh safc worthless.. all i want to know is does anyone have a safc on a 00-01 rs and does it still work? and where do you go to tune it? because you cant really tune it to perfection yourself so oyu have to take ti to a reliable shop that knows what they are doing..and no where aroudn me does anyone know an RS, so they will just F up your car, clossest place is rallispec in nj for tuning...Im just curious to what you all are doing and if you just buy the safc and tune it yourself making it kind of pointless into getting an safc...... i really want oen but it seems stupid on buying a product that some peopel say it will or will nto work and if it does only at wot..and then ok it works, who is going to tune your car? impreza rs's suck
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Old 08-01-2002, 03:33 PM   #9
BMW Man in 2.5RS
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Ok about the map sensors dont hondas use map sensors and AFCs always work in hondas i just think its the matter of the closed loop while not at WOT therefore it wont read an outside voltage like the afc but at WOT its open loop so it will work. Most shops with a dyno will be able to tuen your car. Well as long as they have a wideban O2 sensor and an AWD dyno. With the wideban they can adjust your fuel according to that. Thewy dont have to be specifically experienced with the RS just with the AFC...Joe
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Old 08-01-2002, 03:40 PM   #10
jeffg
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Okay, whoever said the SAFC will not work with a MAP sensor is wrong. The sensor is a 5 volt unit. The SAFC has more than enough ability to control this signal. That was never part of the problem.

The issue has always been weither or not the stock ECU will learn that you are adding or taking away fuel and correct the fuel trim around this. So you end up with a car that is still rich, even after you take away fuel. How long it would take for the ECU to learn this, or even IF the ECU would learn are still a mystery.

I will say, that for the money of an SAFC, and ITC, you could get a greddy emanage and not have this problem. With the Emanage injector harness, the Emanage controls the fuel injectory pulse width directly. This way you dont have to try and trick the ECU into changing fuel.

just my $.02.

J
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