E85 fuel map for EMS-4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 07-05-2013, 10:29 PM   #1
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Default E85 fuel map for EMS-4

I was thinking about running E-85 every once in a while and wondering if anyone is running it with an EMS-4. If so, I would love to see a copy of your fuel map. Also would there be other adjustments to the map that would be needed?
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Old 07-08-2013, 12:34 PM   #2
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EMS-4 does not have flex fuel capability. You can run flex fuel you will just need to make sure you have the correct fuel system capacity and capability for it. Tuning for E85 is not complicated. The VE of the engine does not change if you run the same boost level. This means you will only need some global and a few minor fuel table changes to get the fueling correct. You will be able to add in some timing to take advantage of the fuel. You will also need to significantly increase the starting fuel parameters.

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Old 07-08-2013, 03:00 PM   #3
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Is there a master fuel trim where you can change all of the fuel output by a %? Increase that to 30% and then fine tune from there. That is the simplest way for few reasons.. u wont need to **** around with ur cranking maps, the first tank you switch from gasoline to e85 you'll need to gradually increase ur master fuel as the gasoline in the fuel lines is used up and the e85 mixes with the rest. So when you put e85 and crank you'll be cranking at 0%, then a minute later you'll be at like 3-5% then 10 and then so forth up to 30%.
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Old 07-08-2013, 03:47 PM   #4
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Is there a master fuel trim where you can change all of the fuel output by a %? Increase that to 30% and then fine tune from there. That is the simplest way for few reasons.. u wont need to **** around with ur cranking maps, the first tank you switch from gasoline to e85 you'll need to gradually increase ur master fuel as the gasoline in the fuel lines is used up and the e85 mixes with the rest. So when you put e85 and crank you'll be cranking at 0%, then a minute later you'll be at like 3-5% then 10 and then so forth up to 30%.
There are ways to do a global fuel trim. You can do it through the Alt fuel trim, You can offset Boost Fuel Trim, You can offset User Fuel Trim.... Even using the fuel trim you will still have to alter your cranking maps. Using the fuel trim will not have any advantage over just adding the fuel % to the fuel map and rescaling the map.

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Old 07-08-2013, 04:11 PM   #5
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Using the fuel trim will not have any advantage over just adding the fuel % to the fuel map and rescaling the map.

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The difference is you're changing only 1 setting to 30% and finetunning only your fuel map while if u go the other way you'll need to do every single setting that controls fuel delivery, ve map, the cranking map, the enrichments, and bunch of other things... You're right you'll end up at the same goal however changing 1 tiny number is a lot easier than changing every single setting to get to the same final number.
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Old 07-08-2013, 06:05 PM   #6
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The difference is you're changing only 1 setting to 30% and finetunning only your fuel map while if u go the other way you'll need to do every single setting that controls fuel delivery, ve map, the cranking map, the enrichments, and bunch of other things... You're right you'll end up at the same goal however changing 1 tiny number is a lot easier than changing every single setting to get to the same final number.
In most cases you will not need to modify the the other tables.

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Old 07-08-2013, 06:08 PM   #7
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You see when you switch to e85, everything in your gasoline tune is 30% leaner... Your cranking table now needs 30% more fuel or ur **** wont start properly, your ve map is leaner (obviously), your transitions are leaner so every time you stomp the throttle you are burning 18afr, mat enrichments need to be adjusted some, the list goes on but what do i know i've been running E85 for 2 years now.

Last edited by triple88a; 07-10-2013 at 05:41 AM.
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Old 07-08-2013, 06:12 PM   #8
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In most cases you will not need to modify the the other tables.

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Wrong, you will still need to change all the tables because target AFRs for E85 should be different. You can idle at leaner ratios, you can have leaner ratios in boost, etc. The only reason you need to be 11.8 AFR or richer in boost on gas is detonation resistance that comes with rich AFR. E85 already has insane detonation resistance so you can run richer than that.

inb4 someone says "BUT AFR NUMBERS FOR E85 ARE ON A DIFFERENT SCALE" - **** you fаggot I'm using gas scale.
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Old 07-08-2013, 06:24 PM   #9
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You see when you switch to a fuel that has 30% less energy everything is 30% leaner... Your cranking table now needs 30% more fuel or ur **** wont start properly, your ve map is leaner (obviously), your transitions are leaner so every time you stomp the throttle you are burning 18afr, mat enrichments need to be adjusted some, the list goes on but what do i know i've been running E85 for 2 years now.
You obviously don't use an AEM. I said a global adjustment to the fuel table and some other minor adjustments. Whether you make the major adjustment in the fuel table or a comp% table, it doesn't matter. Making minor adjustments to other tables may be necessary. I don't know why you are arguing with me. If you have tuned one car for two years or 5+ cars over a year you cant really say you are the know it all for E85 tuning.

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Wrong, you will still need to change all the tables because target AFRs for E85 should be different. You can idle at leaner ratios, you can have leaner ratios in boost, etc. The only reason you need to be 11.8 AFR or richer in boost on gas is detonation resistance that comes with rich AFR. E85 already has insane detonation resistance so you can run richer than that.
This is what the global adjustment plus some minor adjustments are for..

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inb4 someone says "BUT AFR NUMBERS FOR E85 ARE ON A DIFFERENT SCALE" - **** you fаggot I'm using gas scale.
What are you even talking about?

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Old 07-09-2013, 03:32 PM   #10
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Originally Posted by triple88a View Post
The difference is you're changing only 1 setting to 30% and finetunning only your fuel map while if u go the other way you'll need to do every single setting that controls fuel delivery, ve map, the cranking map, the enrichments, and bunch of other things... You're right you'll end up at the same goal however changing 1 tiny number is a lot easier than changing every single setting to get to the same final number.
You keep saying VE map. The EMS4 DOES NOT HAVE VE CAPABILITY, it is INJECTOR PULSE WIDTH ONLY. If it did have VE capability you would just change the value for fuel stoich from 14.7 to 9.8 and multiply your statup and cranking enrichment (and maybe transients depending on what strategy you use) tables by 1.3.
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Old 07-09-2013, 04:57 PM   #11
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Oh gotcha i was referring to specifically to the fuel map that hte ecu runs.
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Old 07-10-2013, 03:16 AM   #12
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You see when you switch to a fuel that has 30% less energy everything is 30% leaner...
Stoich ratios and energy content aren't the same thing. Please stop posting and go back to high school chemistry class.
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Old 07-10-2013, 05:30 AM   #13
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Stoich ratios and energy content aren't the same thing. Please stop posting and go back to high school chemistry class.
The more i read that the more i see how i worded that wrong. You're right they arent the same thing but when switching to e85 you need to add 30% of fuel to get the afrs to the ballpark ratios and then fine tune from there.

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What are you even talking about?

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E85 has a different scale for stoich. To give the example for gasoline you want to be 11.5-12afr in boost, if you use an e85 and use an e85 specific reading you want to be at 6.8.. 14.7 is stoich for gasoline, on a e85 specific scale you'll be at 9.765 etc. However you can use a wideband set for gasoline when u use e85 but the numbers change a bit. Thats what hes talking about. Using a wideband set for gasoline while running e85.

Last edited by triple88a; 07-10-2013 at 05:47 AM.
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Old 11-05-2013, 05:16 PM   #14
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Stoich ratios and energy content aren't the same thing. Please stop posting and go back to high school chemistry class.
Sorry, read this thread and had to chime in.
I have a masters in chemistry, so your advise on further education is not needed. (atleast for me, not sure about yourself)


What tripple88a said was actually correct. The engery content and a/f ratios are in direct relation to each other. He did NOT say they were the same thing like you claim he did, but implied one was the result of the other. VERY big difference.

Gasoline has an engery content of 46.4 MJ/Kg (see wiki)
E85 has an engery content of 33.2 MJ/Kg (I calculated this using 85% ethanol and 15% gasoline)

This equates to a nearly exact 30% less energy. Now when burning fuel in our internal combustion engines, the reaction consumes fuel + Oxygen = heat and water (crudely explained). So, if something contains 30% less fuel (or engergy), it consumes 30% less oxygen (I can supply the reaction if you would like). Therefore, burning 100cc of E85 would consume exactly 30% less oxygen than 100cc of gasoline. Now since the engine volume is a constant, and every revilution (at the same pressure) consumes an exact same volume of air, the same injector pulse with E85 vs gas would give an exact reading of 30% leaner. Conversely burning 30% more E85 would consume exaclty the same amount of oxygen as gasoline. Your wideband A/R meter would read the SAME number in the last example. So if your tuning a car using E85, you want the meter to read just as though you were using gasoline. I do this alot and miraculously the fuel map reads 30% higher.

Though he may not have known he was right, it does not change the fact that he was.

The reason it works out this way is that the OH group on ethanol does not yield any significant engery when it consumes a H atom compared to when 2 hydrogens react with one oxygen. Ethanol has only two carbons and 5 available H's. Gasoline has a plethera of different chains and some with double bonds but the everage overall for gasoline comes out to be 30% more available to combust than ethanol. (per volume)

Last edited by cukali; 11-05-2013 at 05:28 PM.
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Old 11-05-2013, 05:19 PM   #15
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[QUOTE=triple88a;1029549]You see when you switch to e85, everything in your gasoline tune is 30% leaner...QUOTE]

This actually is correct.
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Old 11-05-2013, 05:29 PM   #16
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Something about your energy density math doesnt add up. I get 43.5 MJ/kg for standard pump gasoline. Which gives a ~25% less energy, while requiring 30% more fuel to be in the combustion chamber results in ~4% more energy in the combustion chamber.

And helpful tip, posting with your ton here with a post count of 1 is a quick way to get run out of town.
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Old 11-05-2013, 05:41 PM   #17
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The reason it works out this way is that the OH group on ethanol does not yield any significant engery when it consumes a H atom compared to when 2 hydrogens react with one oxygen. Ethanol has only two carbons and 5 available H's. Gasoline has a plethera of different chains and some with double bonds but the everage overall for gasoline comes out to be 30% more available to combust than ethanol. (per volume)
Thanks for the explanation. One of the questions that gets asked here a lot is why E85 makes more power than gasoline when all else is held equal - gas-equivalent AFR, ignition timing, etc. Care to shed some educated light?
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Old 11-05-2013, 09:27 PM   #18
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Something about your energy density math doesnt add up. I get 43.5 MJ/kg for standard pump gasoline. Which gives a ~25% less energy, while requiring 30% more fuel to be in the combustion chamber results in ~4% more energy in the combustion chamber.

And helpful tip, posting with your ton here with a post count of 1 is a quick way to get run out of town.
Well heres the thing the energy output and the stoich have nothing in common so treat them separately.

I said 30% increase to make the afrs correct however the power output isnt the same as gasoline. Also in cruise you can safetly lean out E85 as it still remains stable even at leaner mixtures of even 17.5afr on an unmodified afr gauge (stoich e85 is ~15.5 using unmodified gas gauge)

On the other hand, leaning out gasoline in cruise will start bucking and misfiring around 16 with stock spark.

In other words in wot you end up increasing wot afrs by about 30% however in cruise you only increase values 20ish % from the regular gas table.
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Old 11-06-2013, 12:13 AM   #19
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Thanks for the explanation. One of the questions that gets asked here a lot is why E85 makes more power than gasoline when all else is held equal - gas-equivalent AFR, ignition timing, etc. Care to shed some educated light?
E85 doesnt make more power. It only allows for more optimal spark timing.

For a fuel to make more power it would have to carry its own source of oxygen.

Nitromethane for ex carries oxygen with it so you could essentially say it makes more power than gasoline.

E85 carries no oxygen and neither does pump gas....at correct mixtures they make equal amounts since all power comes from atmospheric oxygen and therefore since engine volume is constant power would be constant if both could run on optimal spark timing.

E85 of course is much more knock resistant plus has a little more cooling effect on incoming air making it slightly more dense. This is a small effect compared to spark timing. Some very well designed engines have great quench abilities and are much more resistant to knock and so do not benifit as much from E85 as other more mild or factory engines.

For ex, I have a few KA24DE engines that knock very easily as 14lbs of boost and only 15 degrees advance. On the dyno I am still making much more power with each degree more I add. I make the most around 20 degrees (about 25 more whp) but the knock is fairly prominent at that timing. When I use E85 or race gas, I can run 20 degrees timing and not detect any significant knock. If I were to run E85 in a NA engine that doesnt knock even with 87 octane and optimal spark, then E85 or race fuel would achieve no more power. Power does not come from fuel alone, if this were true then adding more fuel would create more power...when actually its the intake air that determines the power made from an engine. As long as you burn all the oxygen in the incoming air, you have achieved the maximum power (if engine timings were equal).

To summarize, E85 does not create more power but allows a more optimal spark timing which allows for more efficient burning and more power. This of course only works in engines that cannot achieve optimal spark timing without knocking.

Now if what you said about all other things being equal such as "spark timing" and you create more power, then there is another variable that you havent found. If an engine has knock control and the ECU is in constant knock retard then E85 would allow the ECU to not pull timing and make more power. I see this alot and its probably where the myth of premium making more power then regular. Also on some high HP turbo engines running high boost E85 can cool down the intake charge much more than gasoline making the air more dense. I see this in engines that are pushing around 18+psi boost in hotter weather. Without more information, I cannot answer your statement as far as "all things being equal", because if they were, they would make equal power.

Just to add....some high performance flex vehicles make much more power on E85 than regular. This is not because E85 makes more power. You can see this in the ECU tables, they always add more spark with higher amounts of Methanol detected by the fuel composition meter. They also have a much higher compression ratio than standard vehicles.

Last edited by cukali; 11-06-2013 at 01:28 AM.
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Old 11-06-2013, 12:28 AM   #20
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Something about your energy density math doesnt add up. I get 43.5 MJ/kg for standard pump gasoline. Which gives a ~25% less energy, while requiring 30% more fuel to be in the combustion chamber results in ~4% more energy in the combustion chamber.

And helpful tip, posting with your ton here with a post count of 1 is a quick way to get run out of town.



Gasoline is 46. Look it up again.
Gasoline with 10% Methanol is 43.

So, one needs 30% more fuel, one needs 25% more fuel.

You want to rely on math, then calculate how A/F ratios do not coincide with a fuels energy content. Methanol needs ~60% more fuel (than gasoline) and coincidentally has ~50% less H to oxidize than Ethanol. 30% is twice 60%. How much more would you add to a fuel table to start tuning methanol? Fuel composition is basic knowledge taught. Have you even checked the ECU trims in a Flex vehicle? Tell the designers a fuel's energy content has nothing to do with A/F ratios and let me know what they say.

Lastly, I do not "get run out of town". I school people (literally)

Last edited by cukali; 11-06-2013 at 12:56 AM.
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