SAFC II reads throttle pos of wideband??

[scottiedawg66]

I just got SAFC II, and after reading the manual a few times I got an idea. I'll give some background info before I continue. SAFC II reads throttle position based on a 0 to 5 volt input. based on these inputs a high and low throttle position are selected, and VF readings from the AFM are manipulated. Well, rather than let throttle position determine the manipulation of the VF readings, why not allow wideband readings manipulate VF readings in conjunction with RPM. Widebands also output in 0 to 5 volts. My idea is to set the voltage reading for 12:1 afr as high throttle, and 11:1 as low throttle, and ONLY MAKE CORRECTIONS above 3750 RPM. This way, anything above 12:1 AFR will cause the SAFC II to correct VF to keep AFR below 12:1 above 3750 rpm. this would make no corrections during use below 3750 rpm, and have no effect on closed loop ecu operation. but anytime I am above 3750 rpm, I'm gonna be in open loop any way? Please discuss and flame away, I just got this idea laying in bed last nite.

~scott

 

[CPT Furious]

My...brain...hurts...can't...think...straight...

It sounds strange, but I'll look in my manual, too...I think it might still try to fill the gap between idle and 3750 RPM, just looking at it right now, I don't think it'll work that well, but I will ponder it tonight as well.

 

[Ckanderson]

ok... so what about low load high rpm situations? you dont want 12:1 then...

 

[garrettrowe]

Open loop to closed loop doesn't switch at a set rpm. At low rpm the a/f can be wildly different depending on load. You need to actually see a wideband output, and then you could see why we don't do this.