LTFT/STFT on e85 ...

[CincyJohn]

I've read a lot of the archive threads on this topic, so I think I know the answer already, but I am just checking.

Just recently switched to JDL UEL catless headers, switched the OFT to off-the-shelf 2+ e85 (MY2020 BRZ, US manual. 10k miles). I am on my second tank of e85 and I have no idea what the actual ethanol percentage of the gas is (the pump says guaranteed between 51% and 83%). I have looked at my STFT/LTFTs off and on and they are consistently between +/- 3%. I haven't heard anything I would describe as knock (or anything I think sounds odd at all).

I think this is all fine and there is nothing I need to worry about, but could someone confirm? Also, do I need to keep checking my LTFTs/STFTs every time I put in a new tank of fuel? Or maybe just every time I put in a new tank from a new station? I am assuming that most stations around me (at least from the same company) are providing the exact same e85 mix.

Second, it is weird but my computer estimated gas MPG has not changed much - if anything it has gone down from 28MPG to 27MPG. Does this make sense?

[tomm.brz]

you need to post a log here to make us able to see what s happening

[BigTuna]

That all seems normal. If the ethanol content changes, the tune will adjust for it. the fuel trims might look a little off until it does so. Unless you're seeing over +/-10%, you're fine.

The MPG reading doesn't change, as I don't think it's actually calculated on fuel used.
https://www.ft86club.com/forums/showthread.php?t=74754

More E85 info bits:
https://www.ft86club.com/forums/showthread.php?t=67310

[CincyJohn]

Originally Posted by tomm.brz

you need to post a log here to make us able to see what s happening

I will soon. But it is difficult because I do not have a laptop that I can readily use. Just want to make sure that STFT/LTFT (in addition to an actual knock sound) are the keys to ensure you aren't doing any damage.