E85 to e51 =\

[HLHachiRoku]

Hello everyone,

So here in AZ they have gotten rid of E85 and replaced it with "flexfuel" E51% or tad higher. (might be close to 60, not really sure) I have been having -10% to -17% LTFT now due to this. It also feels a bit hesitant as well, not showing much knock tho on the logs. I have a feeling there is more knock then what its showing however.

What % would you say should I set back timing? OL fuel table? Also im assuming i would have to rescale the MAF as well due to it being so negative LTFT now as well? Thoughts, suggestions? Thank you so much!

[steve99]

If its consistent at E50 then you could adjust your tune timing and fueling to suit

if its varing ethanol content or your going to use different e85 sources that may have up to 85% ethanol then your going to need a flex fuel kit and tune the oft guys now do these for na cars asxwell as turbo

[phrosty]

Pretty sure I remember Shiv saying he reached MBT around E40-E50, so you might not need to adjust timing if you're not getting knock.

[HLHachiRoku]

@steve99 sadly it wont be anything more then e60 here if it gets that high even. So i can adjust the maf table to stop having such negative ltft then? Im getting hesitation sometimes, even bogging but not to much knock so the flash point may be to advanced then im thinking since its already taken out the extra fuel? The negative ltft is consistant ever since they switched the fuel over though. Ill have to play with it alot, dont really want to go back to our crappy 91 we have here as the power gain i had with e85 was amazing after i got it dialed in lol.

@phrosty hrmm im getting hesitating when getting on it or bogging sometimes its not showing the knock, only but here and there sometimes. Its to rare to even worry to much about it as iam is still 1. Really wish our legistature would have left that alone, the smell was amazing! Lol not so much anymore haha.

Thanks again!

[theadmiral976]

Originally Posted by HLHachiRoku

@steve99 sadly it wont be anything more then e60 here if it gets that high even. So i can adjust the maf table to stop having such negative ltft then? Im getting hesitation sometimes, even bogging but not to much knock so the flash point may be to advanced then im thinking since its already taken out the extra fuel? The negative ltft is consistant ever since they switched the fuel over though. Ill have to play with it alot, dont really want to go back to our crappy 91 we have here as the power gain i had with e85 was amazing after i got it dialed in lol.

@phrosty hrmm im getting hesitating when getting on it or bogging sometimes its not showing the knock, only but here and there sometimes. Its to rare to even worry to much about it as iam is still 1. Really wish our legistature would have left that alone, the smell was amazing! Lol not so much anymore haha.

Thanks again!

Once summer gets here, they will up the E% in the fuel mix. Right now, most refineries are mixing lower % EtOH as they don't want cold start problems. While the south shouldn't see much below E75 based on temperature drops this time of year, it sounds like someone high up in the food chain is lazy and has decided to give AZ low-E fuel like the rest of the country. Here in Michigan, we are at E60 during the winter and get up to E80 in the summer despite our gas station stickers saying E51 or higher. You will need a flex-fuel kit if your stations have indeed switched to offering a range of E% fuel dependent on time of year.

[HLHachiRoku]

Unfortunately, the state legislature mandated its only going to be 51% to about 60 being the highest year long, why i have no idea. Loads of poeple are upset lol

[theadmiral976]

Originally Posted by HLHachiRoku

Unfortunately, the state legislature mandated its only going to be 51% to about 60 being the highest year long, why i have no idea. Loads of poeple are upset lol

Wow, that's ridiculous. Based on this: https://www.svtperformance.com/forum...-this.1121571/

I would say that Arizona has legislated laziness. The only reasoning mentioned is that they don't want to have to switch EtOH %s anymore as during the cold season, the vapor pressure of E85 doesn't meet EPA requirements (they have to add in additives and/or drop the E%). Now gas stations only have to carry E51 or something similar year-round.

That is very unfortunate...

[HLHachiRoku]

Ya i didnt even notice until the ltft were dropping and sitting steady at -. Also the club member here who is turboed posted the letter he got in the mail about it, i was like.. woah seriously. Lazy they sure are, politicians lol.

[steve99]

You coulld get the fuel trims lower again with maf scaling

but it could also be done by altering the port injector scaling adjustment and the direct injector pressure tables. Both these tables are adjusted in the E85 tunes by 30% to increase fuel delivery, with such low ethanol content you may be best lowering the uplift factor from 30% to say 20% in those tables, this should bring your trims down without having to adjust the maf scaling which would be a hack. The maf determines engine load and that in turn determines ignition timing fueling cam timing, if you alter the maf scale large amounts you will throw off the load which will alter the tune

[HLHachiRoku]

@steve99 I'm looking at the list of tables. Are you talking about (Injector Flow Scaling BRZ) for the injector scaling adjustment(if my memory serves me right, lol)?

Its at 228.05 on the 91 map and 171.xx on the e85, roughly 24.99% different technically. I changed it to 193.xx. We'll see how it works haha.

I also changed the (GDI Pressure Multiplier A and B) They were at 31% increase roughly. I moved them to a ~20-21% increase now.

Hopefully this will help some and I don't have to mess with MAF again, haha. Thank you again!

Originally Posted by steve99

You coulld get the fuel trims lower again with maf scaling

but it could also be done by altering the port injector scaling adjustment and the direct injector pressure tables. Both these tables are adjusted in the E85 tunes by 30% to increase fuel delivery, with such low ethanol content you may be best lowering the uplift factor from 30% to say 20% in those tables, this should bring your trims down without having to adjust the maf scaling which would be a hack. The maf determines engine load and that in turn determines ignition timing fueling cam timing, if you alter the maf scale large amounts you will throw off the load which will alter the tune

[steve99]

Originally Posted by HLHachiRoku

@steve99 I'm looking at the list of tables. Are you talking about (Injector Flow Scaling BRZ) for the injector scaling adjustment(if my memory serves me right, lol)?

Its at 228.05 on the 91 map and 171.xx on the e85, roughly 24.99% different technically. I changed it to 193.xx. We'll see how it works haha.

I also changed the (GDI Pressure Multiplier A and B) They were at 31% increase roughly. I moved them to a ~20-21% increase now.

Hopefully this will help some and I don't have to mess with MAF again, haha. Thank you again!

Yeah the injector flow scaleing brz is the port injector, the other one injector scaling is left over and does nothing.

the gdi are for direct injectors.

you need to upscale them from the original petrol tune values

the injectpr scale brz is upscaled about 30% as well 171*0.31=53 171+53=224

so its upscaled arround 30% like the gdi pressure tables

you need to upscale them same amount or you will unbalance the pi and di systems

so start with the petrol pi and di values and upsacle them 20% instead of 30%

see what the ltft looks like you might have to adjist the scaling a little higher or lower but keep pi and di same.

then check for knock look for iam=1 and no negitive FLKC and minimal if any FBKC or knock correction.

dont look at KCLearned its not knock

[HLHachiRoku]

@steve99 Ohh weird, i didn't upscale as I took the 91 map at 228.05 injector scale brz and took 21% off that along with the other tables. As every e85 table, wayno or oft base, i have seen is 171.10. which is around 35% from the 91 tables. The GDI pressure a and b table were 21% off. Why would they vary like this if they are supposed to be the same %? I'm worried why the pressure is lower with e85 then the 91 tune? Since it needs more fuel correct or is it backwards on purpose? Thanks Steve!

Originally Posted by steve99

Yeah the injector flow scaling brz is the port injector, the other one injector scaling is left over and does nothing.

the gdi are for direct injectors.

you need to upscale them from the original petrol tune values

the injectpr scale brz is upscaled about 30% as well 171*0.31=53 171+53=224

so its upscaled arround 30% like the gdi pressure tables

you need to upscale them same amount or you will unbalance the pi and di systems

so start with the petrol pi and di values and upsacle them 20% instead of 30%

see what the ltft looks like you might have to adjist the scaling a little higher or lower but keep pi and di same.

then check for knock look for iam=1 and no negitive FLKC and minimal if any FBKC or knock correction.

dont look at KCLearned its not knock

[steve99]

Withe the port injection the injector scaler is based on the injector flow rate in cc/min standard injectorts aprox 228.

In the E85 tune you "fool" the ecu into thinking the port injectors are about 30% smallet ie 171 so the ecu calculates it need to open the injector longer to deliver the fuel required. So smaller number here means more fuel delivered.


Withe the Direct the numbers you alter are the pressure multipliers so the bigger the number higher the pressure more fuel delivered.

The scale changes to each system may not be excatly the same though.

So it might be best to calculate the change factor on each system then remove the same percentage amount from each factor.

[Vmax911]

Hey guys,

Looks like the same thing has happened here is New Mexico. I usually flash the E85 tune for the summer, but when I got to the gas station I noticed a new sticker that read 51%-83% Ethanol (last year it read minimum 70% ethanol). I decided to get e10 instead until I did more research.

Is there anything inherently bad about running with a high LTFT, as long as it is in the range that the ECU can compensate (I think +/-20%)? If I remember correctly, Shiv had mentioned that the E85 tune was based around a 70% ethanol content and that the fuel trims would handle any variation from that. I am familiar with adjusting the timing to prevent knock, but I have never played with MAF, fueling, DI/PI ratios, etc.