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Another e85 thread.

fMErunnin

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So, search function is only showing me one thread of long tunes, ngauge... whatever, so here is my question.

2019 GT and I want to do e85, but my local gas station only measures 70 to 75. Will that difference be problematic? What does the flex fuel tunes do? Is that only for mixing octane and ethanol? Or can you run e85 on those tunes and it just gives you the option to run a mix if needed?

Or if someone that can actually search that can post a great how to thread?

Thanks in advance!
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dirtwarrior

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Good question I am in waiting for the other guys to chime in
 

TX5OH

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For a dedicated E85 tune you should be fine with 75% E. But don’t quote me. Lol

Flex tune adjusts the tune according to the gas/ethanol content.
 

NGOT8R

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I have 91-93 pump gas, Flex and E85R tunes. It’s true that many gas stations that sell E85 are not consistent with their ethanol content. Federal Regulations say that the ethanol content can range between 51% - 83%. I have been to several gas stations and each one has been different (seen anywhere from 62% - 84%), according to my E85 test kit. What I do is run my flex tune 95% of the time because the ECM can still control timing as needed. I personally only run my E85R tune when I know ethanol content is 85% or higher (have had 90% with One Ethanol S), although some are comfortable running their E85R tune at 75%+. Not saying that this is a bad idea, but I personally don’t trust doing that in my car. When I run nitrous, I will definitely use One Ethanol, unless I get lucky and find 85% ethanol at one of the local gas stations. The Flex is nice because you can run an’t combination of pump gas or ethanol.
 
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fMErunnin

fMErunnin

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So, if you run e85 and the flex fuel tune, you are essentially covered on all aspects of fuel ratings; including 91 mixed with e85, just e85 or less?
 

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NGOT8R

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If you do it, I suggest getting all of the tunes that I mentioned In my first reply. When I did mine, I spent $879 for my nGauge and all three tunes. Well worth it for maximum flexibility. Note: On the E85R tune, the ECM does not adjust timing like the Flex. The tuner expects that you will have confirmed your ethanol content before using this tune, so that bad things don’t happen.
 

PaddyPrix

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Depending on your tuner, but mine suggested only using Flex to get to e85 in the first place. If you haven't already run, you pretty much get your gas tank down pretty low (1-2 gallons left) and fill the rest up with e85, which should generally put your EtOh% pretty much over 70%, but certainly over 40% if you're putting in at least half a tank. The Flex tune is more of a safety thing, and run it for a bit to burn whatever's left of the 91/93 off, and when it comes time to fill up, there's so very little of the old gas left that you're good to go on a full e85 race tune.

Again, check with your tuner, but their bare minimum for them should be 70 or 75, and that's to give you a little wiggle room should you get a shitty batch or whatnot.

If your area is real lousy, I guess you could ask your tuner for a slightly wimpier tune, or keep a high octane with you and mix a gallon of say, Q16 to get you over that minimum. That said, Q16 is pretty spendy, and if you're always blending in something that's like $12/gal, might as well just save the money and pay for a custom tune to save in the long run, big whoop if you make like ... 10hp less.
 

Matthewstorm

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Can you mix E85 and 93 with no special tune?
 

NGOT8R

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Can you mix E85 and 93 with no special tune?
I had to edit. I misread your question. I do recall people saying they have been able to mix E30 with pump gas and no tune without any problems. I doubt it will be much of a benefit power wise though. Getting a tune is what will wake your car up.

Will you be running long tubes eventually? If so, I’d install those first and then get the tune so that you don’t have to pay for revisions later.
 

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Matthewstorm

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Yes you can do this on the Flex tune.
No, I mean, with no flex tune. I will have the Roush tune and cannot change that.
Maybe I'm not understanding what the Flex tune is.
 

PaddyPrix

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Can you mix E85 and 93 with no special tune?
I mean you could, but it wouldn't do you much good. It'd probably run like garbage too. The stoich for gas is 14.7:1, where anything lower is rich (less air, more gas), and anything above is lean (more air, less gas)... compared to the e85 stoich is 9.85:1 ... which is why people say e85 uses 1/3 more gas, which yeah, it does. I don't know if the stock computer knows what the EtOh% is, and to what level it'll compensate for it, but you'd be better avoiding it.
 

NGOT8R

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No, I mean, with no flex tune. I will have the Roush tune and cannot change that.
Maybe I'm not understanding what the Flex tune is.
There are people on here that mix E30 with pump gas and no special tune. The Flex tune in simple terms just gives you flexibility to run any combination of pump gas and E85, while making more power.
 
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fMErunnin

fMErunnin

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Timing aside, what about o2 sensors? Do they still read correctly or will you car show it is running rich on e85.. with the flex tune?
 

WildHorse

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but my local gas station only measures 70 to 75
Well if it never goes above 75%, split the difference and get a E73 tune (ya mathematicians I rounded up haha).

Timing aside, what about o2 sensors? Do they still read correctly or will you car show it is running rich on e85.. with the flex tune?
Yeah they read correctly. Keep in mind you'll only see 10:1 AFR on your dash though. So don't go by that haha.
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