Thread: The defacto guide to tuning your car for e85.

Originally Posted by timboku

Dhp you can just import the 42.5 ifr chart thats built into power tunner.

I tried this and i get an error #130, error generating import menu. So that's out. But i searched the forum and found a couple of threads about changing it manually and thats how i came up with my 33/42.5 calculation.
I'm pretty sure it's not a vac leak since before E85 trims were always close to 0. After switching to bigger injectors on stockish tune they stayed between +10 and 0. Normally somewhere around 7, or while cruising up to 13, but never negative and almost never 16.4.
I'm convinced the new trims are related to me messing something up while tuning the ifr and skew rate.
Even more so because I reflashed my pcm back to the old tune after the crooked numbers a bit ago and it went back to how it was, with no crazy stft and not pegged around 16 ltft. Drove around for 30 mins, car was good, numbers looked normal.

I don't want to thread jack your great guide Frosty so i'll stop posting my tuning fail questions here.

Sticky for useful info on E85, in hopes of reducing the amount of E85 question threads and how do I tune this threads.

Second this motion. Way to go jerbear

This method #4 of E85 tuning is new to me. I am about to convert this weekend.

I will try this method. Thank you.

Originally Posted by charlieRobinson

This method #4 of E85 tuning is new to me. I am about to convert this weekend.

I will try this method. Thank you.

Let us know how it went! I'm going to run my tank out then make the switch.

This method works..done it on multiple cars..it's a great write up.

So I do not even touch the IFR table except for adjusting it for my injectors?

I only change the cylinder gain table ? I was always told to alter the IFR table for E85. so...strange..

Cylinder gain in effect is telling the pcm it needs more fuel per cylinder without raping your ifr table. In my opinion the only thing that changes is stoichiometric value and that's what needs to be changed. But most v6 guys don't want to click through everything to do it. This way works just like raping ifr can. You're putting in a arbitrary value till you get your desired a/f.

It makes sense if E85 requires ~30% more fuel to increase the gain from 1 to 1.3.

I just installed the new pump and I have the tune ready. Going to drive around until empty then fill with corn and load tune.

Thank you!

I am so tempted to make the switch... Gas just shot up 15¢ a gallon across the board and I think E85 is still well below $2 a gallon. So somebody level with me... I do approximately 460 miles a week all highway, 5 days a week to work... So I pretty much average 30 mpg... How bad of a hit will I take on hwy mpg? Assuming I can continue to keep my foot out of it and drive normally?

Originally Posted by WickedGoat

I am so tempted to make the switch... Gas just shot up 15¢ a gallon across the board and I think E85 is still well below $2 a gallon. So somebody level with me... I do approximately 460 miles a week all highway, 5 days a week to work... So I pretty much average 30 mpg... How bad of a hit will I take on hwy mpg? Assuming I can continue to keep my foot out of it and drive normally?

It's not gonna be good. I get 14 mpg mixed driving about 150 miles a week. On longer trips i average 20 mpg on the interstate. Sometimes 19.

I'm also semi-extensively modded. So other factors come into play. But don't switch because of the price of 93, do it for the benefits. The price is good but the mpgs suck so it'll even out.

EDIT: I should mention that stock i only got about 25 mpg on the hwy. For some reason mine has never been great on gas.

The mpgs aren't that bad..I daily 500+ who and get 25 hwy... Tune it right and it's not terrible. Worse yes but not terrible

I can live with 25 mpg on the highway... The benefits of E85 do out weigh gas so that has been a thought as well... Would be nice to baby cam, drop to a 3.0 and not have to worry about fuel or not intercooling... Just thinking out loud on the modding part.... I am definitely giving this a lot of thought...

I did find that bumping up fueling by 20% was fine for my swap. Not even 20%. 18-19% was perfect moving up from a great gasoline tune on the same hardware. I keep hearing this 30% figure and I know it's too much for my setup. My LT/ST fuel trims are always +/-10% and the delivered fueling always matches commanded according to my wideband. It's amazing how much power you can build safely with this fuel. $1.79/gallon today.

went through my first tank of corn and I am loving it. Car feels great and MPGs are not terrible at all. Also using less than 30% more fuel with e85 with excellent fuel trims.

Hey, Frosty. Hope you and the other experienced corn burners here can help.

Using this write up, my car is running just wonderfully. I have scoured the net in hopes of finding some proven data for WOT tuning but have found a skew of information with nothing to guide me in the right direction.

I understand all engines even similar builds will behave differently, but what AFR, timing, and PSI should I be looking for at WOT?

I am current seeing ~10.5 @ 18 degrees with ~12.2PSI on a 2.9" pulley on a gen V bolted to an L67.

I think I should lean out to low 11s? I have read some are running as high as 25 degrees of timing advance @WOT? I saw one dude say 14PSI of boost?

What should I be aiming for?

Thank you very much

I believe anything over 21 or 22* timing is useless. I've even heard that on e85 anything over 17* sucks. As for boost psi that's all subjective. Aiming for it is useless since it depends on so many things. Just aim for a pulley size that you can run without knock and get what you get.

And for afr I've run as low as 10.4 wot in pe and seen no difference than running it at 10.8 - 11.0. I believe that's because e85 is God's fuel, but don't quote me on it.

Why Is your enrichment leaner than the stoichiometric value of the fuel. If stoichiometric of e85 is 9.85 ish going up is leaning it out you need to shoot lower not higher