The only difference between my truck and yours is injectors, fuel pump, fuel pump bucket and the flex fuel (tune) added to the ECM.
Thanks Brah, I really didn't want to get that technical but I appreciate you doing so.Need to inject more fuel when running on E85. IIRC it has a higher oxygen content, which is part of why it was stipulated in the first place (going back to the early 80's and oxygenated fuels--MTBE was otherwise used). I suspect the exhaust coming out would indicate the same "richness" factor, IOW running at 14.7:1 (give or take); but the raw amount of fuel into the engine changes. Normally the ECU monitors, well, everything, to see if anything is amiss. If suddenly it has to inject in twice as much fuel in order to stay at 14.7:1, it can surmise that something is broken (well, hopefully it can do that). Not only that, but under full throttle, when it needs the most fuel, E85 needs to flow more fuel through the injectors, again requiring at least the injectors to be different.
Ethanol is more corrosive, but given how E10 is the norm today I'm not entirely sure that the fuel system (outside of raw flow) has to change. Or it shouldn't, had it be designed properly in the first place... Really, IMO it comes down to the fuel map, and the timing map. Need to inject more fuel in, and you can tolerate more timing, thus the ECU has to change maps.
Sending unit and switching module also. I've started a parts list to see what all needs to be changed to run a non ffv Ecu so it can get flashedThe only difference between my truck and yours is injectors, fuel pump, fuel pump bucket and the flex fuel (tune) added to the ECM.
E85 requires more fuel because it burns much cooler which allows more fuel and air into the cylinder.