10° This week. e85 or 93
 

I've have run 4 tanks of e85 with Shiv's OFT tunes. I need to fill up after work and am trying to decide if I should stick with e85 or go back to 93. With the sub 10° temps, it takes at least two cranks to get fire in the morning. I'm getting about 20mpg but paying $3.18 as opposed to ~26mpg and $3.68 per gallon. I can't make up my mind.

Here is a bunch of my logs: http://datazap.me/u/luckrider

Honestly - I have heard it is good to cycle your fuels i.e. For every 3-4 tanks of E85, fill up 50% or 100% of your tank with 91/93. Perhaps it is not necessary but I heard it is good practice.

I finally had to give up E85 when the temps dropped near freezing over night.. Cranking the car for 5-10min in the icy morning just becoming too much of a pain. :( I'll go back to it once the temps get warmer.

Cold starts above 15° seem to be just fine. It is the below 10° that makes it stumbling starting with a cold engine. I think my station is pumping ~e70.

You're talking about 15 Celcius I assume? In which I totally agree.. that's where I'm starting to see the cut-off for long crankings in the mornings too before the engine fires up. Makes me wonder how the factory Flex-fuel cars (my friend's Tundra, for example) start up so easily even when temps are freezing? If they can do it, I'm hopeful a good tuner will be able to figure it out eventually.

It's -2 right now. About to head out to start up the BRZ. Wish me luck! This should be a new record, but it has started on the first crank at 0 before (did stall once). Winter blend of E85 makes the difference. Fuel trims are still minimal, runs great.

Fahrenheit. My guess is that the flex fuel cars adjust their IPW with a special compensation table dependent on the e%. It has been figured out in our cars and I have a modified tune with different cranking Injector Pulse Width table values. I just haven't used it because the e85 tune gets better the longer you run it unflashed (because the learning of the computer us pretty good). I wasn't having starting issues so I didn't change anything.

You're talking Farenheit? Man, mine's won't even crank for ~10min if it's under 30 F degrees! I do miss filling up with the cheaper E85 price too. I got Ecutek so I gotta find someone who knows how to adjust the cold cranking for me.

@reeves, What tuning solution are you using?

Ecutek.. they allow you to modify your own tunes now, but I gotta dish out an additional $300 to get that upgrade. I'd rather just find someone who knows what they're doing to try & adjust it for me. I'm happy with my E85 tune, just not the cold cranking part.

Shiv reckons his tune is good for between E60 and E85, maybe you could do a Mix of E85/93 to drop your E content to around 60-70 for easier starts.

I thought you could actually tune the car yourself with the free software. I thought the upgrade was for multiple maps, custom maps, table comparisons and some other stuff that isn't needed to actually tune the car from scratch yourself. @jamesm can probably give better insight to that. With the OFT and RomRaider, I can edit the Cranking tables myself.

I can switch between premium and e85 as freely as I like?

With a tuning solution like the OFT or ECUtek, you just flash a new map for the fuel you are running. For about $2,000, you can get ECUtek and the needed hardware to run a true FlexFuel setup.

I think I might just flash the modified 1.42b map I have and stick with the e85.