05 SPORT TRAC - EMISSION CODES - BANK 1 & BANK 2 TOO RICH

[LSHOE]

Needing some help on a recent problem with my 05 Sport Trac 4.0L (K ) Flex Fuel Vehicle.
I have always used Unleaded 87 Octane in my truck, until recently. I ran one full tank of E85 through it, and within 3 or 4 days my truck threw 2 emission codes - P1072 Bank 1 too rich and P1075 Bank 2 too rich. I am assuming that the codes are related to the E85, since I have never had this problem until I used the E85. I have since went back to using Unleaded 87 Octane. I had a friend use his scan tool to clear the codes, but the service engine light came back on within a couple of hours. I assume that the codes will be the same , but I will not know for sure until later this week. I was told that I may need to have my truck re-programmed (???), but was not given any further details.
Has anyone else had a similar or same problem occur? Thanks for any help given

 

[LSHOE]

UPDATE -- Problem solved. Tech 1 scan tool was needed to clear codes and recalibrate fuel trim levels. The E85 fuel made the fuel trim levels go so far out of control
that the engine computer could compensate enough to bring them back into the normal range. No explanation as to why this problem happened, since I do have a Flex-Fuel vehicle and my engine's computer is supposed to know what to do with the fuel trim level (air fuel ration) for unleaded fuel and E85 fuel .

 

[ERUSH97XLT]

My Owner's manual for my '13 talks about using E85 since it's a flex fuel model. IIRC it advises against abrupt changes in ethanol content - i.e., don't switch from E0 to E85 in one tank; gradually switch by using E10 and E15 over the course of several tanks so the computer can adjust.

Maybe this is old school thinking nowadays, but I try not to use ethanol at all. Maybe these modern engines and fuel systems are better equipped for caustic alcohols, but I've never had the same performance and reliability by using ethanol in any concentration compared with pure gasoline.