AFR Adjustment for 10% Ethanol

[Chalky]

If we have a constant supply of 10% Ethanol fuel, wouldn't it be necessary to alter stoich settings and make similar adjustments in all fueling points such as PE and CFOL just to name two.

Based on what I see, stoich for 10% Ethanol should be around 14.11:1

[GMPX]

If we have a constant supply of 10% Ethanol fuel, wouldn't it be necessary to alter stoich settings and make similar adjustments in all fueling points such as PE and CFOL just to name two.

Based on what I see, stoich for 10% Ethanol should be around 14.11:1

I am not sure, I just found 'E10' locally, I was going to give it a go at some stage to see what went on.

Cheers,
Ross

[kbracing96]

E10 has been around the mid west for a LONG time (10+ years?). You could reset your stoich and tune for it if its all your going to run, but it's lower enough content, that your trims should have no trouble adjusting for it with out tuning for it.

You won't get as good of mileage on it either.

[Chalky]

Two questions:

if you run OL, this should also mean adjustments to PE and CFOL as well I would think We have had 10% ethanol blend here for some time as well. What got my interest was looking at tune from a 07 LS7 Corvette. They have a table that adjusts for % of ethanol being used. As the ethanol content rises, the lower the numeric value become for stoich.

I continue to tune for a wide open AFR of ~ 12.95 and stoich of 14.67
If stoich for 10% ethanol is 14.11:1 would wide open AFR then become 12.39:1 or would Wide open AFR be reduced by 3.8%, teh same % as stoich?

[Chevy366]

Same around here (10+ years) , I asked this same question and I see you are getting about the same kind of answers , I don't think 10% Ethanol is enough to make any difference .
Gas mileage does suck with E10 .

[Chalky]

Makes me wonder if this may be part of the reason GM, that I know of, has always been very rich by normal standards in PE. I am just curious to know what affect 10% E has on performance if any and on AFRs.

Interesting Reading. I can't attest to the accuracy but it follows my simple logic.

http://forums.corvetteforum.com/show...ht=Ethanol+AFR

[5.7ute]

Here is a good experiment. Change B3601 from 14.63 to 14.11 & save. Do a file compare with both tunes & only B3601 will be different. However if viewing in AFR opening 2 instances will show that all your fuelling tables are different.
This shows that the PCM sees all the fuelling tables in EQ ratio & it can see no difference between the tables. So ideally they will only need modifying when chasing the different burn characteristics of the fuel.
If I am correct then this means that only B3601 needs changing as long as the rest of the tune is dialled in correctly.

[Chalky]

Here is a good experiment. Change B3601 from 14.63 to 14.11 & save. Do a file compare with both tunes & only B3601 will be different. However if viewing in AFR opening 2 instances will show that all your fuelling tables are different.
This shows that the PCM sees all the fuelling tables in EQ ratio & it can see no difference between the tables. So ideally they will only need modifying when chasing the different burn characteristics of the fuel.
If I am correct then this means that only B3601 needs changing as long as the rest of the tune is dialled in correctly.

A little confused. Are you saying after adjusting B3601 and then logging, WB02 AFR will show changes throughout the various settings and not just idle as an example? If so, what that not be a function of STFT and LTFT?

If you ran in OL, would you not also have to make corresponding changes in PE and CFOL tables as well as any other table that came into play?

[5.7ute]

Sorry about not being clear.
Once you change B3601 all the fuelling tables will adjust when saved & reopened. For instance if B3601 is at 14.63 afr(EQ of 1.0) and pe was set at 12.5 afr (1.17 EQ) changing B3601 to 14.11 afr (EQ of 1.0) will make pe change to 12.07 afr (still 1.17 EQ)
This is the main reason you need to start thinking in EQ ratio when using anything other than petrol.
Then on top of that you need to adjust your wideband & pids to use EQ ratio. I have something roughed up I will try to find & post up. It was set up for ethanol but should be able to be modified.

[Chalky]

Got it. Just difficult to think in terms of anything but AFR. Old habits are hard to break.