Hey everyone...

Lately, I've been thinking about getting retuned on 91 octane (having a 91 map in addition to having an E85 map).

Refilling up on E85 literally every week is starting to get killer. Not too bad, yet...but it has got me thinking.

What do you guys thinking about getting a 91 map in addition to my E85 map?

Right now, I am running E85. My train of through is that, I would switch to my 91 map for daily driving, and use up the 91 and switch to E85 for weekend driving or whenever I feel like it.

Is there any downside to doing that? Any potential risk factors you guys could foresee?

Thanks!

As FPS Russia would say..HAVE A NICE DAY!

 

Not a good idea. You have to choose either 91 or e85. Can't really have both. There will be a crap mixture in your tank so when you witch to e85 for the weekend and give it one hard pull *Boom*. The other way around dosent matter.

 

Since it looks like you were tuned by EQ, i would contact them and see what you turner thinks.

 

Hopefully Ed will see this post and chime in.

 

That's backwards. Since an e85 tune injects 30% more volume of fuel, it would be running rich with a mix of 91+e85 on the e85 tune.

It's not impossible to have two maps, but you do have to be careful when switching back to a 91 map. Filling up on 91 when the gas tank is near empty helps, the ecu can deal with some ethanol, some gas stations have e10 as their 91. So if you have a gallon of e85 in the tank and fill-up with 12.5 gallons of 91, you'd roughly have an e10 mixture, probably closer to e5.

 

E85 map with some 91oct is no good. Needs to be 100% E85 in the tank, lines, and rails to feel good about doing hard pulls. Over the course of 3-4 years of running E85 I found that out the hard way. That's why some tuners are making people run on E85 for a week or so to clear the 91oct out of the system with a limp map before the actual tune.

Some E85 in a 91oct gas tank is ok. Prob does some good. But running on a 91oct performance map with too much E85 will be bad.

You won't be accurate unless you have measuring cups at the gas station and know the % of 91/85 in your tank at all times.



Just don't mix.

 

E85 is a real touchy fuel. I've even had trouble (hesitation issues, backfiring, crap idle) with diffrent brands of E85. I just go to one station. I won't go to another.

 

So is putting 2 or 3 gallons of e85 in my gas tank once every 3 tanks a bad thing? I'm stage 2 91

 

I've seen some people even mix in like 10% E85 or maybe 5% E85 with their 91 fuel.

I know it won't be a big deal if I do it because I usually refill up with E85 way after my fuel light comes on, probably about 2 gallons left

 

Idk. You'll have to ask Cobb if that's ok. Or a tuner or machanic, I'm neither. I was just talking out of my own expiriences.

 

E85 is so unpredictable it's really not a safe fuel unless you check out what % is E85. I got a bad batch of E85 and it made my car run like crap and smoke, after checking out what % it was it was E70. Race Gas is much better and is always consitant, might not make as much power but you atleast know its good fuel, better then replacing a motor over bad E85.

 

alright, thanks man.

 

Np.

 

The reason for tuners having people run e85 for a couple of tanks is the tune isn't done on something like e70. Do a tune on e70 and then fill-up with e85 will make your car run lean.

 

I have a 91 and E85 map. Have only used my 91 map twice since I was tuned on E85. If I do run 91, I'll run down the 91 till its almost empty, I then fill up on E85 and switch to my e85 map but keep the boost down at 18psi(91 map boost level). Ill run at least 3 tanks of E85 before I even think of turning up the boost to 21psi and doing and hard pulls. Havent had any issues and car still runs strong.

I only average about 30-40 miles more per tank on 91 compared to E85. On 91 I'd go about week and half before filling up, E85 I usually fill up weekly