S-AFC tuning

[mx3TT]

Ok guys. Read just about every single post about the S-AFC on a SOHC mx-3 ECU and harness and I havent got a thing from them as far as tuning. I am running a BPT that is basically stock with the exception of the MSD ignition and Blaster 2 coil and intake and exhaust. I am using the 1993 mx-3 ECU and harness. For you guys that are using close to the same setup, what are you settings like? What did you set the airflow at on low throttle and high throttle? Wherever I look no one ever shares their secrets. Let it out guys!

[JWMotorsports]

Perform the following at YOUR own risk!!! Extreme caution is advised, sever engine damage could result from improper tuning.

Basic tuning is done using a air/fuel ratio gauge, I recommend a wide band if you can afford one and they ARE worth it! Have a KNOWLEGABLE friend ride with you and get them to help you tune it. Start by tuning the low throttle setting for your idle mixture untill it stays stoich (it usually just bounces at idle)or as close as possible to it. Then slowly start driving at about 1/4 throttle holding the car at each rpm point while you tune the mixture for each point to stoich. Then after setting all your points in 1st gear at 1/4 throttle you have to test each gear and get it where is NEVER leans out. Rich is better than lean. Then you have to do it at half and then 3/4 throttle. Once you have made sure it doesn't ever lean out on those then its time to do full throttle the same way on the high throttle setting. This is the only way to do it, then take it to a dyno for fine tuning if you like. Double check all your settings for sensor voltage direction and airflow meter settings first.

<small>[ January 08, 2004, 08:27 AM: Message edited by: JWMotorsports ]</small>

[Shady469]

also be sure to compensate for more boost when under full throttle.
if your looking for percentages mine is kind of like this:(on a b6t with 370cc injectors)
lo throttle:-30%@idle going to -22ish% @4k
hi throttle:-30%@3k going to -17ish%@6.5k
but this isnt guess work:i took the correction % i used on the SOHC as a base. then i divided the 230cc(stock cc) into the 370cc(i did 350cc to have more room for tuning later on) to find the percentage(1.5217). i then applied those percentages to the correction percentages.
i know its confusing ill post the chart i made when i get home.

[mx3TT]

Good information guys. I would like to see the chart whenever possible. Anyone else of any tips?

[Shady469]

as promised:
for the 330cc's: 230/330= .6969= .3031= 30% varience @ idle for stoich
for the 350cc's: 230/350= .6571= .3429= 34% varience @ idle for stioch
and my projected maps:
230cc's:
Lo throttle +5-+9
1k-4k
Hi throttle +5-+15
3k-6.5k
330cc's:
Lo throttle -25--21
1k-4k
Hi throttle -20--10
3k-6.5k
350cc's:
Lo throttle -30--25
1k-4k
Hi throttle -25--15
3k-6.5k

and for those that might be using the HKS with 370cc's:
800 -30 3550 -21 6350 -15
1350 -29 4100 -20
1900 -27 4650 -18
2450 -25 5200 -17
3000 -23 5750 -16
These are safe base maps that may be a tad rich but in no way compensate for increases in boost pressure. there fore anyone using these maps takes on full responsibility for any damages that may occur.

<small>[ January 08, 2004, 11:22 PM: Message edited by: Shady469 ]</small>