dang... I think you need to learn about engine theory before you start messing with S-AFC. google search " engine theory".

 

You can't adjust timing with the SAFC, which is why it is the least recommended tuning device. You will be indirectly manipulating the stock ECU timing maps by changing the AFRs.

You don't tune for closed loop (14.7:1 stoic). Just let the ECU control that. It works perfectly with no changes to the Lo-throttle settings until you upgrade the injectors.

Tune the WOT open loop AFRs to the 11.1-11.5 range and ensure the timing is steadily increasing to around 19-20 degree at 7k rpm.

The reason why you do 3rd gear is because there isn't enough load in 1st and 2nd gear to do it...and because a 4th gear pull requires that you go nearly 120mph, which is not feasible unless you have access to an abandoned airstrip. 4th gear tuning preferable, but 3rd is the most practical.

 

i'm pretty sure the throttle % settings are cut off point for low and high map. for instance, if you set it Low->20% and High->50%, that means that from 0-20% throttle, the ecu is in close loop (use the front O2 sensor the achieve stoich) so the safc does not effect the fuel at all, from 20%-50% throttle the safc uses the low fuel map and any thing higher 50% throttle, the safc uses high fuel map.

 

No, it's what I said above. Anything below the low throttle point is affected by the low-throttle fuel settings. Anything above the high throttle point is affected by the high-throttle fuel settings. Anything between the throttle points is averaged between the low and high throttle fuel settings.

 

you're right Warr, i just looked at the safcII manual and it's exactly what you said.

When the throttle opening is set to Lo-10% and Hi-50%, the air correction factor at a
throttle opening of 40% is as follows;

● At a throttle opening of 50% or more, the air correction factor is equal to
“Correction factor set at Hi-Thrt +3%”
● At a throttle opening of 10% or less, the air correction factor is equal to
“Correction factor set at Lo-Thrt -1%”

※The air correction factor at a throttle opening of 40% can be obtained by the following formula;

(3%-(-1%))×(40%-10%)/(50%-10%) + (-1%)=2%

 

I have my S-afc II tuned with settings from Buschur Racing. There are not many changes for the low throttle settings, just a few %. The big changes come with the hi throttle settings.

 

I have a question about this. I basically understand how the thing works. Let's say the correction factor at higher rpms for the hi throttle settings is set at -17%, is that making it richer? I assumed that it was taking fuel away making it leaner.

 

Negative numbers on the safc is taking fuel away making it leaner.

 

Ok, that is what I thought, thanks. Help me out with one more thing please! Early in the thread it was mentioned that 14.7:1 is optimal when cruising, but when you go to wide open throttle you afr should be like 11.2:1, speaking generally. Now is 11.2:1 is leaner than 14:7:1? Call me stupid but I think this is were I am getting confused when learning this whole air/fuel tuning thing. I was thinking that 11.2:1 was be richer than 14.7:1. It wasn't making sense to me becuase my S-AFC is taking fuel away at hi throttle (i used settings provided by buschur racing for the mods that I have) making it leaner, but than I see people say things like the 11.2:1 ration at wot, and here I am thinking that the is richer than 14.7:1. hope that makes sense.

 

lower numbers are richer, higher numbers are leaner. so 11.2:1 is richer than 14.7:1.

You need to be richer at WOT since there is more load, airflow, etc.

 

Ok that is what I thought. I think I just cleared everything up in my own head. Tell me if this makes sense. When go to WOT the ECU is making the the ratio richer, because of more air, load, and so on. When taking away fuel in the hi-throttle settings with the S-AFC it is just not letting the ECU go as rich as it would normally, keeping some more power. My issue was the I was not thinking clearly and realizing the S-AFC just leaning out what the ECU does. Before it was like the ratio say is 14.7:1 cruising, and it at WOT the S-AFC is making it leaner from there, which is wrong. Sorry about all the questions and what not, just trying to learn more and straighten myself out. Thanks

 

actually, half way on the pedal isn't 50% throttle. It's little less than half.

 

HUH?