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Old 04-25-2005, 08:58 PM   #1
AJs99RSAWD
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Question Apexi S-AFC

I was wondering if purchasing an AFC for my 1999 2.5 RS would be worth it. It only has a 2.25 catback exhaust and Cobb CAI on it now. I was just basically wondering if I were to buy it, what types of gains should I look to be getting? Thanks!

-AJ
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Old 04-26-2005, 03:41 PM   #2
AJs99RSAWD
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Is this a bad question or is are there no people that can answer it?
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Old 04-26-2005, 04:38 PM   #3
Nat
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When I had my 99RS I remember discussions saying that the only way you could make power with an intake was to make sure that you had some sort of fuel correction device, S-AFC, etc. I had a JC Sports intake, Jumptronix O2 voltage meter and the S-AFC. After installation of the intake I could tell from O2 voltage that the car was running leaner, so I used the S-AFC to add fuel until the open-loop voltage matched what the car ran stock. At the time this was a common setup and before driving it I used correction values a litle lower from what other members had found to work, and ended up adding a bit more fuel till I was happy. Intake in addition to the exhaust made the car feel much better, I was surprised that I even had a butt-dyno gain on the low end. The theory behind this was that intakes weren't necessarily designed properly and that turbulence caused the MAF meter to read a lower volume of air entering the engine despite it being the opposite. So, the ECU leaned out the mixture, and on top of the added air the car ran even leaner making it actually lose power over the stock intake. The S-AFC was used to correct this and make the engine happy. I'm not sure what the Cobb intake is like, maybe they compensated for the turbulence. I think Rallispec did the same thing, basically mounted the MAF far from the cone filter inlet to let the air smooth out. I believe that SCC did dyno testing on a 2.5RS with intake and found that without fuel correction you'd see a drop in power from stock, with fuel correction you'd pick up 10 or so hp. Sorry this isn't a great answer - you'll have to research and see what Cobb recommended. Trying checking out the 2.5RS web page, those guys would probably give a better answer.
Nat
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Old 10-03-2005, 12:44 PM   #4
MrHEX
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I know this is old news. But I am just getting in this now and every one has a list of pros and cons to say about this. The biggest things I see is the fact that you have no control over your timing and that since this unit is not very smart, you can actually get WAY too lean to blow your block. Well letís say if I was to install a wide band to go along with this unit. And since Iím running a SOHC I donít have to worry about timing and all that. Would I get any power gain? Or is it even recommended? Or do I have a 3rd option with the same amount of $. I know I can invest in a complete stand-alone unit for around $1000 USD, AEM makes some real nice ones. But I really donít have that kind of cash, nor am I running any kind of force induction. So what are my options?

Thanks for advance.

HEX
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Old 10-03-2005, 05:23 PM   #5
Storm
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Assuming you have a SOHC EJ25, you have a knock sensor that will pull timing. You should be able to feel this and let off the gas and pull over to add fuel to the settings. I don't think you'll be pulling fuel from the tables anyway. Just because you can pull 50% of the fuel...doesn't mean you should.


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Old 10-04-2005, 02:27 AM   #6
MrHEX
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Thanks Jay

I didnít mean to lean it down by pulling back. I meant, say after adding the intake and the cat back. The stock ECU doesnít always add the extra fuel needed to get the most out of the so called ďMODísĒ so I was thinking about the S-AFC or even better S-AFC II to make it run a bit richer to get a bit more juice out of the EJ25.

HEX
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