Commanded vs Actual AFR, OL, STFT Rich Question

[05_Silver]

Been researching and playing around to better understand the open loop tables and trying to reach different AFR's. For example, Stoich is set at 14.7, Open loop EQ ratio is .93 in cruise areas at operating temp (just for testing purposes) which shows 15.8 commanded AFR. I can tune the VE to within a few % error using the wideband at that 15.8 but as soon as I turn STFT on it forces low-mid 14's and keeps throwing fuel at it. Is STFT always going to the stoich value or are there other key variables at play here I'm not understanding? All LTFT are disabled and cleared.

Any clarification is appreciated! Assuming this is a fundamentals answer but I can post the test tune file if needed.

[5FDP]

All fuel trims will go to stoich.

It would have to be open loop only with zero o2 sensor function if you wanted to commanded something leaner than stoich.

[05_Silver]

Makes sense, thanks for the reply!

[05_Silver]

Finally messing around with this one again and my STFT still forces low 14's it seems when I turn them on from OL. I have my stoich set at 15.2 and you can see as soon as STFT's are on it richens up. Log/Tune attached. I've been dinking around quite a bit so my VE is fairly choppy. The log is fairly long and has a key-off area.

Silver05 - Evening Drive - 110421.hplWorking Tune - 110421 - Stoich Increase VE Big Adjust #1.hpt

Thoughts? I'm just trying to get it a little leaner at idle and cruising.

[5FDP]

Gotta run open loop only if you want to run it leaner than actual stoich of the fuel. Drive slower, make it more aerodynamic or put highways gears in it if you want better fuel mileage.

[05_Silver]

Ok I was thinking the stoich value was actually altering how the NB's were reading. You'd have to fudge around with the calibration I'm assuming or stay in OL as you've suggested twice already I was mainly just trying to get it closer to hovering around the 15 area rather than 14 and help with the rich smell. I usually run ethanol free 91 so assuming it's staying fairly consistent but maybe not.