Car broke down unsure why- e85 oft
 

Hey all, hoping I can get some insight not sure what happened here.

Have been running the stock e85 tune with oft on stock 2018 brz for a couple years without issue. A week ago I got an oil change and state inspection at a local shop.

2 days later Drove it a few miles then tried to floor it and it stops accelerating and turns off. Tried starting it a couple times and car shakes for a bit and turns off (like choking?). Checked Fluids and all looked good from what I can tell.

Had the oft tablet with me and it showed no cel codes and the same e85 tune was loaded. ReRan the same tune and it started up, chokes a bit but gave it some gas and it settled down. Has worked fine ever since.

The shop said they only read the ecu for errors and don’t make any changes. Could the tune have gotten corrupted somehow and was fixed when I reloaded it? Should I post logs (noticed no issues since)? I didn’t take it back to the shop yet, should I?

Timeline/cliffs
— tuned to e85 from regular gas on the previous fill up
— 30 miles on current fillup (filled from same pump as previous)
— get oil change and inspection
— ~10 miles later car breaks down when flooring it
— ran same oft e85 tune that was already loaded
— no issues for week and a half normal and hard driving ~100 miles

I'd suggest posting a log with datazap. It may highlight an issue.

Wont be tune issue if it ran for ages before


might be fuel issue


if the tune get corrupted in ecu which is extremly unlikely the car wont even start. the ecu check the tune checksum every startup if its incorrect no start

Thanks for the responses. Here's a log I captured today. datazap log

other info from the incident: The e85 pump states 70% minimum ethanol. I didn't monitor with the oft after filling up but took it easy for a few miles. I remember flooring it in 2nd gear up to about 5.5-6k rpm then shifting to 3rd and then it stopped accelerating. engine light flashed and I pulled over and it shut down. It would start up again but the RPM would fluctuate a lot then turn itself off 1-2 seconds after.

was also 100 degrees F and think I saw steam when I opened the hood. some water leaking on the ground probably from the AC.

Check engine light flashing is usually misfires, they can be due to fuel or spark issues.


log looks ok nothing major.


ususual for you to see steam under hood, check coolant again.



a/c drain shouldnt get into engine bay

They might have disconnected the battery and the ecu is calibrating itself. The rom file was updated to 4.0 something awhile back too. I would check to see if your running the current version just to be sure.

I’d say it’s that,

I reflashed to a different e85 tune and during the relearn process, after a short drive to the shops my car wouldn’t start. Would crank then immediately stall out and die. I could keep it running if I gave it gas but would die immediately after I took my foot off. I reflashed to my old tune which was still shaky at first but got me home and then settled, no issues since.

The re-learn process seems pretty hit or miss with e85 tunes in my experience

Yeah this sounds similar to what happened. Shop did test the battery so I guess ecu had to recalibrate. No issues since so I’m calling it good

So this happened again. Got an oil change/multi point inspection and decided to reload the same e85 tune afterwards just in case. started fine then realized I needed a state inspection. They told me I needed to drive cycle the car so I drove for a few miles under 3.5krpm, then started going to 5.5k all with light throttle. Car stalled after about 10-15 miles

It would start but wouldn't hold idle. When I pressed the gas pedal I heard a clicking noise but wouldn't rev and just turn off. Had to tune it a couple times before I was able to rev and eventually it held idle and drove it back home.

had 3/4 e85 in the tank. running stage2-e85-v4.0.3 tune

It's odd this has happened after the last 2 oilchange/state inspection with no issues before. I had to get 2 inspections this year as the old one was a year expired. Also these are the first 2 oil changes outside a subaru dealership, both different shops.

not sure these logs will show anything, it's the partial drive home after it settled
https://datazap.me/u/chondo/log-1670955379?log=0&data=1-13

are you member of either the texas 86 group or the more local austin/sa facebook group? may be able to find someone a little more local with experience that can give it the once over.


personally only ran e85 a dozen or so tanks over time without issue. it's a pain in the butt going out way to acquire it here and may years ago the difference of cost compared to 93 was much greater than is now.