Questions about ethanol levels, tunes, and flex fuel sensors
 

Lately I’ve been really thinking about going E85 since the fuel is pretty common where I live. But the pumps around here usually say “51-83% ethanol”. I’m trying to get away with not using a flex fuel kit, since there are enough E85 stations around to always run E85 exclusively and it’s only a weekend car, never going on long trips.

I know that plenty of people run E85 with no kit, and I have read that OFT’s E85 tune works down to E50. But is it okay to run 50% with no flex fuel sensor? Or is there a minimum level required to run without it?

And even if it’s okay, am I missing out on any performance without a flex fuel kit? Or do the car’s sensors and ECU adjust the trims on their own without the kit?

Before I make any decisions I’m gonna get a test tube and sample the fuel from a few stations around here to know what I’m dealing with. Given the season, I’m hoping the ethanol levels are high right now

Thanks

My first answer is just get sensor and be done with it. If you are tuning yourself OFT will get what you want. When you change fuels you will need to re-flash. If you go with ECUTec you can make different MAPS different E content so you will not have to re-flash just change MAPS.



You will never regret going E85, the engine runs smother and it is worth it for the mid range torque change.

Sounds fine and good reason to enjoy

I run NA with no kit. I don't know the minimum ethanol that the OFT E85 tune can handle.. you can keep your OFT out and monitor LTFT and STFT if you are that concerned till you realize hey this is gonna work for now with the E85 you have in the tank. My LTFT are 0 in cruise but even in OL mode (WOT) they don't go beyond +- 3 %. Yes off throttle get spikes.. which is normal even on 93 octane

Yes .. because flex fuel kit allows it to constantly adjust for the amount of ethanol detected so it can adjust quick to changing fuel situations compared to ECU just reacting to it. The OFT is more a blanket tune and it will not have that capability. But it will still run very well if you have stock airbox.

Good luck.. don't over think it. The car will run fine on the OFT tune as long as you are using properly regulated E85, which I doubt you have access to anything less. The flex fuel kitting is expensive and I just don't see it necessary unless it's a track toy, FI, or you just want it.

Thanks man, my only remaining question is does the OFT tune constantly adjust based on Ethanol level detected? Or is that only ECUtek tunes? I already have the OFT and if it’s still gonna be a “blanket tune” regardless of having an ethanol sensor, then I’ll definitely skip it

to my knowledge and what I've seen, it's using fuel trims to react. Quote from Steve99

He is pretty much saying the same and even to the point that you shouldn't maf scale on a e85 tune because it's constatly going to be trimming for different levels of ethanol if and when it varies. Again, I don't see that as an issue mine doesn't vary that much.. I don't have data to show for a whole year my E85 pump variation.. I did say that closed loop LTFT stays around 0 with maybe +- 3 out of closed loop I'm happy with that over the last month or two.. the constantly adjusting tune would be a flex fuel set up. I imagine tuners are doing similar things using Ecutek when they don't have flex fuel kit. If your trims stay +-10 % I wouldn't worry too much although I wouldn't be happy there.. but over that and I would want to get back to petrol tune and find out what's going on whether it's just E85 variance or something else.

yes if you have known stable e85 then you can scale maf on e85


if you have a flex sensor on oft or ecutek flex tune then that is adjustjng for ethanol content

Follow up to this: is there a way to read the ethanol content through the oft after putting on the flex sensor?

The Delicious Tuning kit comes with an app that shows it real time on your phone. I dont know about OFT, but the data is there. There has to be a way to find it. There are other was to have it on a gauge. I've been surprised at how much the ethanol content varies - even from the same station at different times.

I went ahead and spent the money on FlexFuel. I'm toying with the idea of going boosted eventually and figured a more accurate adjustment and the convenience of not having to worry about flashing and where to fill up we're worth it for me. We went on a short weekend road trip just this weekend. Went out on e85, but had to fill up out in the boondocks where I couldn't find e85 to come back home. No worries, hassle free. My tank now has about 28% e85 and my ECU knows what to do with that.

If your daily driving your car get ecutek, and a flex fuel kit. Trust me it's worth the extra $$$

Sent from my GM1915 using Tapatalk

Yes, according to shiv

https://www.ft86club.com/forums/showthread.php?t=53477

He says maximum performance gain is at near E40 and he said there is no need for flex fuel if you are in the e50-e90 range. I was going to buy flex fuel kit but changed my mind after reading this article. It looks like even 91 can be run with e85 tune if you let the ECU adapt but it may pull timing due to low octane (and probably retard it).

As far as I understood, if you have your majority fuel ethanol or you have enough octane you are fine. I think there is no need to increase risk of failure by adding components like fuel lines, sensors, wiring etc.