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Discussion Starter #1
Hey, a thought I had for modding the afm:
Instead of opening the box and changing the spring to modify what the AFM outputs to the computer, couldnt you electrically modify its signal? More specifically, tweak the voltage coming out of the AFM and going to the CPU. I thought of doing something like that on my Camry (similar AFM), but never knew how. Now I have some ideas. On mine (82 5m), the voltage goes from 3.5 (fully closed) to 8 (fully open). I read somewhere it was 5-10, but this doesnt seem to be the case. Anyway, you could easily make something and put it inline to "bump" the voltage up or down a certain ammount, effectively "telling" the CPU that more air is or is not coming into the engine, making the mixture richer/leaner and advancing/retarding the timing. Actually, the reason I thought of this was to correct my idle on my camry, because when I put a K&N on it, it wouldnt idle properly, and would kill. When I played with the voltage, it thought there was a different ammount of air coming in, adjusted the mixture accordingly, and it would idle perfectly. It did not negatively affect performance. I bet you could tweak it for more power, especially if the spring-thing works. Let me know what you think, and Ill try to make something, maybe an easier mod than the spring, maybe better since it would be much less involved to adjust. I see a possible new toy for the MK2 crowd :) :) Maybe Im optimistic, but the least I can do is try and contribute. Sorry for the excessive rambling, just trying to get it all down!
 

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id like to see that, right about now im dreading tuning the car... once its finally running.

im sure a resistor would work to reduce the voltage thats being sent, but raising it such precise amounts would be much harder.

best of luck, and we forum members are here if you need some extra brain power
 

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Perhaps a Potentiometer would work? Along with the aid of a ohmmeter.

I dunno, I failed electronics back in HS. :p
 

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Discussion Starter #4
Lowering the voltage is the easy part, but raising it is the hard part. To make it richer, this is what I would need to do. I know how to raise it to whatever level I want, but the hard part is increasing it a specific ammount over what it is. It can be done, Im sure, Im just not sure what I need to do it. How I did it before, was put 12 volts to that line, and had a voltage regulating switch inline with the 12v to set it to whatever I wanted. I just increased the lowest voltage, essentially. That didnt change the voltage once it raised above a certain ammount.
 

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Such a device can be made to do what you describe, but precision adjustability/tunability could prove to be difficult without more sophisticated and expensive electronics. Modifying the AFM output signal curve in a step-up or step-down (low gain vs. high gain) fashion is not all that hard to do if you have some knowledge of electronics and electronic devices. The tricky part is being able to build a device that actually alters the output curve waveform itself without having to spend a whole bunch of money. :wink: The Split Second box has this capability and is fully programmable, but also expensive since the software used for programming the device is proprietary information. :( Let us know what you come up with! I have a prototype device drawn up on paper that should do the trick, but the cost for just the basic parts to build the device is pretty steep.
 

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Discussion Starter #7
What is the retail on the s-afc?
Ill mess with it and let you all know, just thought I would get some feedback as to if it was a good or bad idea.
 

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You can pick them up for $160-180 on ebay. That is the S-AFC-II, which has some cool options and better adjustability than the original one, its up to par with the split second system as far as adjustability goes.

--BillyM
 

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Discussion Starter #9
Does anyone know where I might find info on the fuel map and/or TCCS and AFM units?
 

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IIRC, I think the name of the web site is "autoshop101.com" Tons of good genuine Toyota training materials and information! I'm not sure if that site is still around though or not.
 

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autoshop101 is still there...I visit several times a week :) for info on the tccs check out Reg's SONIC supra site he gets very(very) technical in his study of the TCCS and AFM systems. Might help.
 
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