AFR understanding

[Green7mgte]

very informative on that landscape.
im just trying to figure out the tuning aspect of it all. Im dead scared to put my afm on it and burn the crap outa my engine.
my wideband will be ordered tomorrow and hopefully comes next week.

[cre]

Well, don't do anything to force the ECU into open loop operation full time (like removing or disconnecting the stock O2 sensor) and keep the low range zeroed out and the ECU will maintain a safe AFR. If anything you may richen up the mids a bit but the ECU will pull fuel to keep the AFR at 14.7 most of the time.

That graphic is a handy reference, but it's not an absolute representation of the best tune for every application; Still, it is a good guide and the numbers are safe.

[Green7mgte]

as of right now my safc low throttle is set to 10 and high at 50
that was its default setting. makes sense.. closed loop from 10% to 50%. anything after half throttle and im trying to put on speed so opened loop it is. i assume.

[cre]

Open loop is when the ECU stops trying to adjust fueling to achieve a certain AFR (usually 14.7:1)... this is around 70% throttle or 2.70v. Trying to tune for any other AFR prior to that point will at best have no effect and at worst cause AFM related error codes and driveability issues. Generally I don't think you'll have driveability issues unless you're using another system which actively alters the fueling to achieve a set AFR such as the MAFT Pro, but it's best to just avoid the headaches. If you want a little overlap go easy on the enrichment you give it over stock and set the throttle level a good higher (try low 60's or above).

There are a few other cases where the ECU operates in open loop (such as high engine loads at lower throttle; like when you start boosting hard at half throttle going up a hill), but as the system operates most of the time in closed loop you should tune with that in mind with the low and mid loads and their set points.