Easy answer is it depends.... if your consistently running e85, or e10, or e(anything) with out switching the ethanol content, then no your car has already learned it and will adapt/ learn fast. If your switching ethanol levels it needs to relearn. Mine used to learn as quick as 10 mins of driving and some times closer to 30 mins of driving.
Who cares what % it is. You have a FLEX tune.
That's the easiest way I know of. Test your fuel for e% so you know where afr should settle.
No, you have to look at the short terms, & for that you need a laptop. Staring at the AFR is meaningless.
Not necessarily. If you know what % of ethanol you have in the tank then you should know where your afr should sit at idle. Once it stops hunting and fluctuating and settles to a steady .3 margin the Lund flex tune has finished learning. I used this method for years before switching back to pump gas. I'm not saying getting your laptop out is a bad idea but it's not always convenient. Biggest thing is you have to test your fuel and know exactly how much e you mixed in the tank. If not you won't know where your afr should be settling.
I do my own tuning with an HPTuners MPVI2 and use a laptop with VCM Scanner software to monitor Alcohol Percent, Inferred AFR Status and Inferred AFR Source while datalogging. I have not worked with an RTD device but it appears it uses the same VCM Scanner software available free from the HPTuners website. At this Lund link, there's some info on using the software with the RTD. Might need to "repoll for supported parameters" while connected to the vehicle after loading the flex tune. Then you should have Alcohol Percent as a channel option to select for logging.
