Lund Flex Fuel Tune - 93 octane vs. E85

therealdannye said:

I've been debating going the E85 route as well since I just moved to Ashburn a month ago and am now 5-ish miles away from an E85 station. But I am curious about one thing with switching between the two gasses:

How far down should you run either tank (93 or E85) before filling up with the other? And if E85 burns faster/gets less mileage, how close should you safely get to empty before filling up?

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Like Darkesthour said, you can fill up whenever and it adjusts. Lund suggested getting as close to 0 miles as you can before changing just so you can get a better idea of the real alch%.

Also, when you fill up you should monitor "alch_learn" on the Nguage. It shows 0 when learning and will show a 1 when it has fully learned and adjusted to whatever fuel you have.

Bluemustang said:

At WOT I was seeing an average of .85 lambda. From 5200-7000RPM timing was 29.5 and 29.75 on spark advance and spark advance v2. I hit 115.31mph in 3rd at 7039 RPMs. Avg. short term fuel trims were 1.00

On full E85 I was seeing about 10 for AFR at idle and about 8 at WOT on my car's dash gauge. I can get as much as 19mpg on the highway with E85 and about 11 all other time (a lot city driving, sitting at lights and time when I'm just idling). I could probably get slightly mpg in the city if was being economical. Max knock was 0 and minimum knock was -10. The minimum knock was -8.65 at WOT.

I don't know much but I do know that positive knock is bad and timing advance is good. Everything appears to be looking good. I love the E85. It even smells good.

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I dont know for sure but the feeling I got from my recent lund tune and log reviews was that there is room for small positive knock that is within factory specs. When you take into consideration the ECU will adjust regardless of the tune if there is too much knock it makes sense. It just means you are at the limit of the power you can make.

For instance my WOT shows at 7900 RPM I am getting:

+1.078 Knock | 0.98 lambda AFR

Up until about 6400 RPM its all negative knock or 0. Im pretty sure a lot of negitive knock means there is TOO much left on the table.

this is all on 93 for me FYI. I love Lund, wont ever try another company again. Forgot to add car scares the SHIT out of me going WOT from 2nd to third or third to fourth even going 40-50 mph because it will chirp and try and break loose lol. Still have stock tires though.

I too am looking into this tune. Thanks for the info! Where did you guys buy your N gauge from?

I thought negative knock means the ECU is adding timing? Maybe I am wrong. Anyway I don't think I can expect to get much more out of it getting 30* timing

89stang said:

I too am looking into this tune. Thanks for the info! Where did you guys buy your N gauge from?

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Went with a Teambeefcake power pack.

Bluemustang said:

I thought negative knock means the ECU is adding timing? Maybe I am wrong. Anyway I don't think I can expect to get much more out of it getting 30* timing

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Correct, negative knock is added timing. Positive values are what you don't want to see. This is contrary to many other platforms where negative is pulling timing.

Bumping an old thread I know. But on the flex map you're ok to run either 93 or e85 and its a good way to get by while you switch from strictly one fuel type to another?

xXoVrKiLLXx said:

Bumping an old thread I know. But on the flex map you're ok to run either 93 or e85 and its a good way to get by while you switch from strictly one fuel type to another?

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Yup running flex you are golden on either or on a combo.

AZ18yote said:

Yup running flex you are golden on either or on a combo.

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Good to hear! Going to the dragon tomorrow and not sure if any E will be up that way. Ill flash the flex when I need to fill up for sho!

Start it up and let it idle at 1,500 or so for about 10 minutes when you go full E85, at least that's what I did and datalogs looked good. Runs better on the dedicated E85R. I'm at E85R but going back to the flex tune and 93 as I'm leaving the E area of the state.