How to tune for e85

[GAFF]

Anyone have tips on how to tune for e85

[noreasonwhyy]

a/f tables. ~15:1 is normal fuel's stoich, while e85 is something like 10:1. you'll need to change the majority of your cells to 1.5x the normal value. keep scanning and making adjustments. i'd get a wideband with an aeroforce to ensure accuracy.

i'm sure someone who actually tunes will be able to tell you more.

[Tengis]

I always start E85 tunes by skewing the injectors 30% - this will do the majority of the fueling changes for you but you still need to MAF tune daily driving and WOT. Do your normal MAF tuning based on LTFTs because the O2 sensor still finds lambda 1. If you have a full open loop tune then I still skew the injectors then wideband tune daily fueling to a 15.2 afr on a gasoline calibrated wideband - I go a little leaner to hopefully gain a tad bit of fuel economy. Of course, you can crank up the timing hardcore on e85... I would start by putting a 2005 GTP timing table into your bin.

WOT fueling will need to be done with a wideband no matter what. On a gasoline calibrated wideband I think max power will be between 11.5-12.5 afr. The "ideal" AFR for max power is broader with E85 - I usually tune for 11.8-12.0s on a gasoline calibrated wideband.

Can find more info about lambda and the AFR #s here actually: E85 in standard engines - Wikipedia, the free encyclopedia

[GAFF]

So one thing first I need to do is tune for the larger injectors?

[Tengis]

So one thing first I need to do is tune for the larger injectors?

Basically do this: If you have 60# injectors use 42# injector information. If youve got 80# injectors use 60# injector information. You are skewing the injectors 30% or so to make up for the 30% extra fuel it needs and then fine tuning it with the MAF table. Some people do it other ways but this is the fastest and gives the same results IMO without changing the numbers in the MAF table a ****load.

[GAFF]

Wait I thought I needed to push more fuel into them not less.. Would I use 80# info for the 60# I got?

Im new to this.

[matt5112]

no, using the info for the smaller injectors will cause your larger injectors to push more fuel.

Look at it this way. Injectors are controlled by pulse, and the larger the pulse width, the longer they squirt fuel each time. So if you use injector info that calls for longer pulses (ie smaller injectors) then your larger injectors will deliver more fuel in the same time as the smaller ones.

Basically.

lets say 12 ms peak on 42.5's is what you needed. Then when using 60's you need 8 ms but you need 12 ms when running E85 with the 60's.

Just run the 42.5 injector info with your 60's and you'll be okay.

pluse width numbers entirely fictitious.

[GAFF]

I understand it completely now thank you matt for clarifying that