E85 and o2 sensors

[TRPCANA]

The other day ran into an odd issue, 2018 GT with 11k miles, 3k tuned on dedicated E85 tune. A few days prior i noticed on cold start my exhaust note was noticeably quieter, happened a few days in a row so i used my ngauge and searched for codes and sure enough there was p0316 for misfire detected on startup (first 1000 rpms). I cleared the code and it did not return. Two mornings ago however i cold started like normal and immediately something was wrong, car was surging in rpms and going from 1000 to 500 and back very quickly, I shut the car off and restarted and same thing, put the car in gear and tried backing out a few feet and car was sputtering and engine was shaking, was very close to stalling out. Pulled back into the garage and after a few restarts with same issue i decided to flash to a different tune. This seemed to solve the problem and was able to drive to work without issue. Sent the logs to my tuner and they said the O2 signals seemed erratic and possible had a failing sensor, however were confused as to why flashing to a different tune worked. I have since not had the problem and its been 2 days and about 200 miles and im wondering what some other peoples thoughts might be, o2 sensor on the verge of failure or just something randomly off that morning? I will not name the tuner, ive had a great experience with them and im not trying to blame them or shame them in any way, and continue to use their tunes.

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[watisthis]

Miss fires maybe due to low fuel? Has happened to me plenty of times. Haven't had o2s go bad and I've been on e85 awhile now could have been bad batch of e85 or maybe somehow you were on the wrong tune. I've tried starting my car on full e85 with my 93 tune and knew immediately.

 

[Andy13186]

I had an o2 sensor replaced after on e85 for a bit, new one hasnt thrown a code yet and Ive been on e85 longer than the first. I do get surging idle sometimes after cold starts until I give it throttle, but it goes away after the first application of throttle. My idle does go rough occasionally but that was happening on the stock tune after the o2 sensor was replaced also, still not sure why that happens. Car hasnt stalled since my tuner raised idle to 750 rpm.

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