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

To get DIC calculations precise, simply multiple the mulipler in TT by the same % you increased the injector to compensate for ethanol.

Thanks Frosty. Worked like a charm here.

Might try and switch to this concept from my current way. May make it easier if I ever want to take a road trip.

Edit: Also, do you find this helps keep the trims more consistant? When the fuel changes around here mine go nuts and sometimes I cant ever get it dialed in again, especially at idle.

Originally Posted by darkhorizon

There is nothing better about having "low trims" vs "big trims"... Its all the same output and there has never been a car that "ran better" because it was closer to 0 on the trims.

Unless the LTFT was outside of your PCM's compensation range. Like, More than or less than 16.4, Correct?

If its not within 10% then something is off on the tune or wrong with the car.

Quick question if possible Frosty, I used your method of increasing the cylinder gain across all 6 cylinders by a percentage. I used 22.5% but that's not my question. My question is after doing this method, my STFT's stay pegged out around 25. Is this normal? Is this just me reading the computer adding the extra fuel i'm telling it to?

Is it +25 or -25? Something isn't right there either way. What's your long term trims?

Pegged out at 16.4 at idle but it moves around a bit. And actually goes to 0 at wot. Car runs about the same so far but I just made these adjustments about an hour ago so I'll see. I tuned it for my 42# injectors, then put my cylinder skew rate to 122.5.
It's +25.

Filled up with e85?

OH yeah. I've been running E85 for about a month by just using 42# injectors on a normal injector sized gas tune. It ran pretty damn good that way. Never LTFT's pegged to 16.4, never any crazy STFT numbers. I just got an AVT box and DHP last week so i figured i better tune it the right way. SO far it's not bad, but i know running this rich isn't good. I just did to WOT pulls till 70ish. Both my long term and short term trims went to 0 and stayed there for the whole pull. But as soon as i start normal driving again, its back to 25 stft and 16 ltft.

Both those numbers move as i'm giving it more or less throttle, but under cruise conditions they seem to stay there. I guess i could have tuned my injectors wrong. I did 33/42. .7857. And multiplied everything in the ifr boxes by that.
Then i bumped the skew rate up to 122.5 for all 6 cylinders.

You should have multiplied your stock IFR table by 1.27

Thats with HP Tuners right? I thought with DHP you divide?

trims pegged at 16.4 and 0 at WOT= vac leak probably

Gotta remember it takes a long time for wot trims to adjust. A better idea would be if its trimming at idle AND not trimming while cruising down the highway THEN you have a vac leak. I don't remember the whole divide vs multiply in dhp.

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

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.