How to run E85 on stock 86 BRZ FRS with OFT tune

[steve99]

Originally Posted by sroby

Steve or kodename47, I’ve been running E85, now everytankfull for a year next month. Do you guys no off any long term effects of the E85 on the fuel lines and system in so much as corrosiveness. Anything in particular to watch? Just curious. Best regards Steve

ive been full time E85 over 4 years, not one tank of petrol, no issues.


the only guy who had issues used some weird fuel additive likely for petrol in his E85 and it turned to jelly and clogged his fuel filter, cleaned filter all good. moto : don't use any fuel additives in E85.

[steve99]

Originally Posted by Robbierayy1

Hey Steve I did more research on this topic and I am understanding this much more! Your posts have helped a ton. My whole goal is to be able to approximate the ethanol percentage in my car by observing the fuel trims on the oft. I was confused so much because I didn't really understand lambda vs afr. Everything would be a lot easier if it was in lambda.

What is the commanded afr for the e70-75% tune in terms of petrol afr since you explained that the ecu and oft read petrol afr?

When I go check my real time display on my oft I see the measured afr right? where would I go to see commanded afr if possible?

as kodename 47 said


the 02 sensors read residual oxygen in exhaust gass, it doesn't know what fuel your burning.


lambda=1 is afr of 14.7:1 for petrol and 9.8:1 for E85


the ecu and logging tools all get scaled to petrol afr values


so even in an E85 tune you see petrol AFR but this is just scaling of the readings not actual.


for OFT E85 tunes these seem to be adjusted for low ltft values around the 70-75% ethanol content


As ethanol content rises more fuel needed to maintain desired afr target so ltft will trend higher, less ethanol ltft will trend lower.


from zero ethanol to 75% ethanol is about 30% fueling increase so roughly every 2% change in ethanol content will result in a 1% change in ltft, this is very rough indication though and will be most noticeable at lower rpm and idle where ecu learns fastest as it spends most of its time there

[steve99]

Originally Posted by pcguru2000

Those numbers are "at the wheels" measure correct?

yes


different dynos different results

[steve99]

Originally Posted by pcguru2000

Any idea why there is a torque dip?

I've heard people claim that it was to get better gas mileage around town. To make higher max HP numbers. To meet pollution standards?

Will the car stock, with oft e85 tune, pass california smog test?

don't rearly know but probably not.


but its pretty easy to just fill with petrol and flash in stock tune ;-)

[Robbierayy1]

Originally Posted by steve99

as kodename 47 said


the 02 sensors read residual oxygen in exhaust gass, it doesn't know what fuel your burning.


lambda=1 is afr of 14.7:1 for petrol and 9.8:1 for E85


the ecu and logging tools all get scaled to petrol afr values


so even in an E85 tune you see petrol AFR but this is just scaling of the readings not actual.


for OFT E85 tunes these seem to be adjusted for low ltft values around the 70-75% ethanol content


As ethanol content rises more fuel needed to maintain desired afr target so ltft will trend higher, less ethanol ltft will trend lower.


from zero ethanol to 75% ethanol is about 30% fueling increase so roughly every 2% change in ethanol content will result in a 1% change in ltft, this is very rough indication though and will be most noticeable at lower rpm and idle where ecu learns fastest as it spends most of its time there

Thanks Steve! I understand the petrol scaling for the car. So if the tune is set for e70-75 than lets say commanded afr at idle would be 10.6 which is lambda 1/stoich for e70-75. I get that on the oft afr would be 14.7 at idle/lambda 1 but real afr would indeed be 10.6 at idle for e70-75. If i put 60% ethanol in my car the stoich for e60 would be 11.28. Now heres my question...would the ecu adjust by adapting to run on the measured afr from o2 or try to compensate to still achieve the commanded afr from the tune? Would fuel trims go negative and decrease from initial commanded 10.6 afr to achieve 11.28 of measured afr? Or would the fuel trims go positive and stick to the commanded afr of 10.6 and add extra fuel so the afr of 11.28 becomes 10.6? Basically which is prioritized for fuel trims...measured afr or commanded afr?

[Kodename47]

Originally Posted by sroby

Do you guys no off any long term effects of the E85 on the fuel lines and system in so much as corrosiveness. Anything in particular to watch?

We don't have E85 here mate so I can't comment. People's experiences on here suggest that it's not an issue though.

[steve99]

Originally Posted by Robbierayy1

Thanks Steve! I understand the petrol scaling for the car. So if the tune is set for e70-75 than lets say commanded afr at idle would be 10.6 which is lambda 1/stoich for e70-75. I get that on the oft afr would be 14.7 at idle/lambda 1 but real afr would indeed be 10.6 at idle for e70-75. If i put 60% ethanol in my car the stoich for e60 would be 11.28. Now heres my question...would the ecu adjust by adapting to run on the measured afr from o2 or try to compensate to still achieve the commanded afr from the tune? Would fuel trims go negative and decrease from initial commanded 10.6 afr to achieve 11.28 of measured afr? Or would the fuel trims go positive and stick to the commanded afr of 10.6 and add extra fuel so the afr of 11.28 becomes 10.6? Basically which is prioritized for fuel trims...measured afr or commanded afr?

at idle the ecu is targeting lambda =1 ie the fuel tables all read petrol afr as that the scaling so no matter what fuel you put in car ecu will attempt to hit the fueling target of lambda 1, to do this it will use fuel trims.


same under load it will always try and target whats in fuel table (open or closed loop,converted back to lambda) so say you see 12.5 afr in fuel table at 6000 rpm load 1.2 then ecu is rearly targeting lambda 0.82 and it will target that value lambda regardless of fuel using fuel trims to adjust due changing ethanol percent.


The ecu always targets what in the open or closed loop fuel table depending on what mode its in. the target afr at any given time is based on load and rpm this is whats logged as "commanded AFR"


The ecu then compares the commanded afr (from the fuel tables) with the measured afr (calculated from 02 sensor reading) if its different it will use fuel trims to try to correct this error. the AFR being petrol afr scaled from lambda regardless of fuel.


you could in the ecu definitions rescale those fuel tables to lambda and the 02 sensor tables to lambda if you rearly wanted to. It just displaying the lamda values converted to petrol AFR as that's what everyone is used to looking at, but confuses things when your running E85


more info here


http://www.ft86club.com/forums/showthread.php?t=64790

[Robbierayy1]

Originally Posted by steve99

at idle the ecu is targeting lambda =1 ie the fuel tables all read petrol afr as that the scaling so no matter what fuel you put in car ecu will attempt to hit the fueling target of lambda 1, to do this it will use fuel trims.


same under load it will always try and target whats in fuel table (open or closed loop,converted back to lambda) so say you see 12.5 afr in fuel table at 6000 rpm load 1.2 then ecu is rearly targeting lambda 0.82 and it will target that value lambda regardless of fuel using fuel trims to adjust due changing ethanol percent.


The ecu always targets what in the open or closed loop fuel table depending on what mode its in. the target afr at any given time is based on load and rpm this is whats logged as "commanded AFR"


The ecu then compares the commanded afr (from the fuel tables) with the measured afr (calculated from 02 sensor reading) if its different it will use fuel trims to try to correct this error. the AFR being petrol afr scaled from lambda regardless of fuel.


you could in the ecu definitions rescale those fuel tables to lambda and the 02 sensor tables to lambda if you rearly wanted to. It just displaying the lamda values converted to petrol AFR as that's what everyone is used to looking at, but confuses things when your running E85


more info here


http://www.ft86club.com/forums/showthread.php?t=64790

Perfect Steve makes sense to me! So just to clarify like you stated before, positive fuel trims will indicate ethanol percentage above 70-75% and negative fuel trims will give you an approximation that the ethanol is below 70-75%? Also Steve I need to change the oil for my car and was wondering what oil I should use that is compatible with e85? Which do you use or which one have you used that has given you the best results? How frequently do you change the oil?

[steve99]

Originally Posted by Robbierayy1

Perfect Steve makes sense to me! So just to clarify like you stated before, positive fuel trims will indicate ethanol percentage above 70-75% and negative fuel trims will give you an approximation that the ethanol is below 70-75%? Also Steve I need to change the oil for my car and was wondering what oil I should use that is compatible with e85? Which do you use or which one have you used that has given you the best results? How frequently do you change the oil?

For e85 make sure oil is GF5 or SN rated or specificly states its e86 compatable


Unless you live in a super cold climate like way below zero a lot id run a 5w30 oil in preference to 0w20


Your correct with fuel trims trends for an oft tune

[Robbierayy1]

Originally Posted by steve99

For e85 make sure oil is GF5 or SN rated or specificly states its e86 compatable


Unless you live in a super cold climate like way below zero a lot id run a 5w30 oil in preference to 0w20


Your correct with fuel trims trends for an oft tune

Thank you Steve so much! You have answered all my questions on the ethanol, fuel trims, and tune. You also explained them very well with good detail which I appreciate a lot! I understand this topic significantly more! Lastly do you have or know any specific brands that you would recommend to use for a car that runs e85 along with the requirements labeled above? I live in southern California so cold temperatures aren't a problem!

[steve99]

Originally Posted by Robbierayy1

Thank you Steve so much! You have answered all my questions on the ethanol, fuel trims, and tune. You also explained them very well with good detail which I appreciate a lot! I understand this topic significantly more! Lastly do you have or know any specific brands that you would recommend to use for a car that runs e85 along with the requirements labeled above? I live in southern California so cold temperatures aren't a problem!

not really across oil brands in usa, but any quality known brand full synthetic oil that SN or GF5 rated, should be fine with E85 or one that states its E85 compatable.

[Robbierayy1]

Hey Steve I was looking into the oils to put into my car and have found two options that seem suitable. Both brands say they are alcohol compatible which are valvoline vr1 and amsoil dominator. However their viscosity's are 10w-30, would this be good to use?

[FRSBRZGT86FAN]

Originally Posted by Robbierayy1

Hey Steve I was looking into the oils to put into my car and have found two options that seem suitable. Both brands say they are alcohol compatible which are valvoline vr1 and amsoil dominator. However their viscosity's are 10w-30, would this be good to use?

You can use a 10w30 as long as it's e85 compatible of course.

The only difference is it's thicker so you get a bit of an mpg hit and if it gets cold it may even be harder to cold start. But noticing you live in california means that shouldn't be an issue.


For me I live in PA and don't want to switch oil types between seasons so I just used 0w20:
https://www.amazon.com/PurOl-Elite-S.../dp/B00F2VE8ZK

I order 6 of those every 3 months because I change sooner than normal with e85 around 4500-5000 miles for me.

[Robbierayy1]

Originally Posted by FRSBRZGT86FAN

You can use a 10w30 as long as it's e85 compatible of course.

The only difference is it's thicker so you get a bit of an mpg hit and if it gets cold it may even be harder to cold start. But noticing you live in california means that shouldn't be an issue.


For me I live in PA and don't want to switch oil types between seasons so I just used 0w20:
https://www.amazon.com/PurOl-Elite-S.../dp/B00F2VE8ZK

I order 6 of those every 3 months because I change sooner than normal with e85 around 4500-5000 miles for me.

Thanks man! Would the 10w-30 oil be better for my car than a 5w-30 under higher loads? I sometimes accelerate aggressively and sometimes go wide open throttle!