So, I'm starting to experiment with ethanol in my Explorer ST. My understanding is that when increasing the commanded fuel flow rates, running too lean is always the concern. In my attached WOT logs, the actual (0.90) vs. commanded (0.76) AFRs diverge more on E30, before changing the PCM's stoichiometric target.

e10_91on_wot.PNGe30_98on_wot.PNG

What are the issues with, say, setting Stoich for E30 (12.96), then alternating tank fills between E0 (14.64) and E50 (11.81)? My thought is the ideal fuel flow rates for both are inside the 20% window within which the PCM can compensate with LTFTs. So if the fuel system can keep up with the flow rate necessary for E50, this should allow a wide range of fuel types as availability state-to-state varies. But it seems with even E30, I'm running out of fuel.