Flex Fuel - Can I build an E85 based map?

s300 and SManager software questions & answers
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DaX
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Flex Fuel - Can I build an E85 based map?

Post by DaX »

I'm running a flex fuel setup with an S300v3 and when it was dyno tuned, the tuner set the base tune on E10, then began blending in ethanol and set the compensations on the flex fuel tab accordingly. However, I'm running E85 most of the time and this got me wondering - would it be possible to do the base tune on E85 and then set the compensations to remove timing and fuel as the ethanol content goes down?

I opened a stock P28 calibration and started seeing if I could set it up this way - initially it looked good. For fuel compensation, I can put 85% ethanol at zero, and then everything below that can have negative values. However for timing compensation, the charts will not take negative values. Is what I'm suggesting silly? Unnecessary? A good idea? Just curious what others think.

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Spunkster
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Re: Flex Fuel - Can I build an E85 based map?

Post by Spunkster »

There is no reason to do what you are suggesting. It has been tuned the proper way and you should leave it as your tuner tuned it.

skaterguy1986
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Re: Flex Fuel - Can I build an E85 based map?

Post by skaterguy1986 »

Don't zero that table out, ethanol fuel quality varies quite a bit, it's never exactly 85%. There is a reason a content sensor and calibration table is needed, the quality is very inconsistent.

DaX
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Re: Flex Fuel - Can I build an E85 based map?

Post by DaX »

I wasn't talking about zeroing the table out. I was talking about setting the table up like this:
Ethanol.png
Ethanol.png (274.28 KiB) Viewed 612 times
Instead of like this:
Gas.png
Gas.png (252.77 KiB) Viewed 612 times
I was just wondering if it were possible to do the base tune on E85 instead of gasoline, and then let the compensations take away fuel as the ethanol content decreases, instead of how it's currently set up with a gasoline base tune and letting the compensations add fuel as ethanol content increases.
The way it's currently set up, if you want to use flex fuel you have to tune on gasoline first then tune for ethanol using the compensation tables to add fuel and timing for ethanol content. As I'm putting ethanol in the tank about 95% of the time, it would seem to me wiser to set up the tune with the fuel I plan to use most (E85).

spAdam
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Re: Flex Fuel - Can I build an E85 based map?

Post by spAdam »

I decided to try exactly this when I started on a fresh calibration a couple weeks ago. It seems to work fine for the fuel compensations, but since I have to have the ignition compensations going the other way (since they can only advance instead of retarding), it's just wonky in the software and I'm thinking about just taking my correction % out of the tables and going back to normal.

FWIW I also tried reversing the order of the ethanol% breakpoints (i.e. tapering from 100 on the left to 0 on the right), as a workaround. ECU didn't like that very much so that idea got burned real quick.

Can't speak for wherever you guys are, but the E85 seems pretty consistent out here. Maybe because it's all coming from the same company, as far as I can tell? It's always 79-80%, except for one tank I got early on at 77%

DaX
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Re: Flex Fuel - Can I build an E85 based map?

Post by DaX »

spAdam wrote:
Tue Feb 25, 2020 11:46 am
I decided to try exactly this when I started on a fresh calibration a couple weeks ago. It seems to work fine for the fuel compensations, but since I have to have the ignition compensations going the other way (since they can only advance instead of retarding), it's just wonky in the software and I'm thinking about just taking my correction % out of the tables and going back to normal.

FWIW I also tried reversing the order of the ethanol% breakpoints (i.e. tapering from 100 on the left to 0 on the right), as a workaround. ECU didn't like that very much so that idea got burned real quick.

Can't speak for wherever you guys are, but the E85 seems pretty consistent out here. Maybe because it's all coming from the same company, as far as I can tell? It's always 79-80%, except for one tank I got early on at 77%
Cool - glad to hear someone else's brain is thinking of the same things I am. And thanks for sharing your experience regarding changing the order of the ethanol% breakpoints. It might actually work if we could put in negative timing values, but since we can't, I think it may be more trouble than it's worth.

Regarding ethanol consistency, when I got 10 gallons back in August to take with me to get tuned, it was only about 65% ethanol. From the same pump the last few months, it's been about 78-80%. I used to have two stations I drove by on my way to work, but one station's E85 pump has been "out of order" for several months. I heard that the manager of that one is trying to get the E85 pump/tank switched over to diesel. That's a bummer, but I understand. They probably will sell way more diesel than E85.

Spunkster - any particular reason that the software was set up to not allow negative values to be used for ethanol based timing compensations?

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Spunkster
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Re: Flex Fuel - Can I build an E85 based map?

Post by Spunkster »

Because it was not designed to do what you are trying and it works perfectly when used the way it was designed.

spAdam
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Re: Flex Fuel - Can I build an E85 based map?

Post by spAdam »

FWIW, I went back on it. Worked fine under normal running but I had massive problems getting the cranking and post start to work repeatably. Tuning as Hondata intends ended up being the way to go. If you really want to favor e85, tune with the compensations and dial it back to run acceptably on gas.

DaX
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Re: Flex Fuel - Can I build an E85 based map?

Post by DaX »

Thanks for the feedback, spaAam.

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