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

[Robbierayy1]

Originally Posted by steve99

OFT tunes will have lowest ltft at around 70-75% ethanol . the will work from about 60-90% ethanol.


On NA cars you achieve max timing MBT at about 60% ethanol content, so on NA cars additional ethanol content (over about 60%) wont allow you to run more timing so it rearly doent doesn't mean more power.


Boosted its different


LTFT % doesn't mean the car is running richer or leaner, LTFT (or stft and ltft together) is the amount of compensation the ecu is applying to the fueling in order to hit the fueling target. So positive or negative fuel trims don't mean the car is running rich or lean .


for that you need to look at commanded afr and actual measured afr.

Thank you for your response! But say I have a tank of 50% ethanol in my car which is below the 60% you mentioned to achieve MBT. Would the ecu retard the ignition timing once it recognizes the ethanol percentage to prevent knock? If we take the 70-75% tune as a reference point then if I were to be at 50% ethanol then wouldn't I be running rich at that moment? The 50% ethanol would be running on the stoichiometric ratio of 70-75% ethanol until the ecu adjusts and the fuel trims go negative to remove the amount of fuel being added to get to the right ratio for 50% ethanol right? If not how can I check the AFR so I could get a better understanding? Thank you for your time!

[churchx]

I'd say, that if you don't have tanks content of E85 you can trust/rely on and it starts to worry you .. just evaluate getting some flex-fuel kit. That should free you from E85 ethanol content, mix ratio in tank, optimum tune for that worries.

[steve99]

Originally Posted by Robbierayy1

Thank you for your response! But say I have a tank of 50% ethanol in my car which is below the 60% you mentioned to achieve MBT. Would the ecu retard the ignition timing once it recognizes the ethanol percentage to prevent knock? If we take the 70-75% tune as a reference point then if I were to be at 50% ethanol then wouldn't I be running rich at that moment? The 50% ethanol would be running on the stoichiometric ratio of 70-75% ethanol until the ecu adjusts and the fuel trims go negative to remove the amount of fuel being added to get to the right ratio for 50% ethanol right? If not how can I check the AFR so I could get a better understanding? Thank you for your time!

Inless you have installed a flex fuel kit and flex fuel tune the ecu has no indication of ethanol %


The fuel trims work purely on the ecu adjisting fuel delivery to try to match commajded afr and measired afr.


If you dont have fill flex fuel setup then you need to run petrol on petrol tune and e85 on e85 tune but the tune can only adapt over a certian range of ethanol percent as it has no reference to ethanol percent.


If you want that you need to add flex fuel sensor and tune


http://www.ft86club.com/forums/showthread.php?t=120397




See here

[Robbierayy1]

Originally Posted by steve99

Inless you have installed a flex fuel kit and flex fuel tune the ecu has no indication of ethanol %


The fuel trims work purely on the ecu adjisting fuel delivery to try to match commajded afr and measired afr.


If you dont have fill flex fuel setup then you need to run petrol on petrol tune and e85 on e85 tune but the tune can only adapt over a certian range of ethanol percent as it has no reference to ethanol percent.


If you want that you need to add flex fuel sensor and tune


http://www.ft86club.com/forums/showthread.php?t=120397




See here

Ah thank you Steve this makes more sense! So what I'm getting is since the tune is set for a base ethanol percentage of 70-75% the fuel trims will do what they can to achieve the commanded/correct AFR for the e85 tune right? Can the ecu distinguish between petrol and ethanol? Or does it just recognize ethanol is in the tank but just doesn't know the percentage of it? Now I'm a little puzzled about the "how" part. If I put 50% ethanol in my car how would the ecu adjust to run like the 70-75% it was set for? Can you explain the actions that would occur and why please? What would the fuel trims look like etc.?

[steve99]

Originally Posted by Robbierayy1

Ah thank you Steve this makes more sense! So what I'm getting is since the tune is set for a base ethanol percentage of 70-75% the fuel trims will do what they can to achieve the commanded/correct AFR for the e85 tune right? Can the ecu distinguish between petrol and ethanol? Or does it just recognize ethanol is in the tank but just doesn't know the percentage of it? Now I'm a little puzzled about the "how" part. If I put 50% ethanol in my car how would the ecu adjust to run like the 70-75% it was set for? Can you explain the actions that would occur and why please? What would the fuel trims look like etc.?

Without the addition of flex fuel ethanol sensor the ecu doesnt have any indication of ethanol percent.


All it does is compare the measured afr with the commanded afr if its leaner it adds fuel if its richer it removes fuel using the learned fuel trims.


When you add ethanol it makes car run leaner as you need 30% more ethanol to achieve the same stoicometric burn as petrol.


You get extra power from ethanol in NA car by advancing the ignition timing as ethanol jas a higher octane rating and jence more knock resistant.


When you running a dedicated e85 tune the fueling is increased about 30% and the timing is increased up to 10 degrees in places.


If you reduce the ethanol % outside the 60-90 range then it doent work well and its possible to damage engine.


Eg if you run 50% ethanol you will run way rich as your going to be oitside what the trims can compensate, this can cause issues with lubrication and you will be running way too much timing and you will get consideravle knock, the ecu will attempt to compensate but its getting outside the limits of compensation.

[pym19109]

Seem like avcs affect MBT of E85 as I have tried.



Red,Blue are Wayne's Rom with pulled 1-2Deg above 6800+rpm to reduce knock

Yellow,Green are using Tor's avcs with original wayne's timing.

Above 5000 rpm torque and hp are significantly different.

[airrick]

Originally Posted by pym19109

Seem like avcs affect MBT of E85 as I have tried.



Red,Blue are Wayne's Rom with pulled 1-2Deg above 6800+rpm to reduce knock

Yellow,Green are using Tor's avcs with original wayne's timing.

Above 5000 rpm torque and hp are significantly different.

what other mods have you done to your car? the 190s hps are sexy to see.

[pym19109]

Originally Posted by airrick

what other mods have you done to your car? the 190s hps are sexy to see.

Gruppe-s header, avo drop-in filter , HKS legalmax cat-back and the true hero is E85.

The power output may not really reliable as I use virtual dyno to measure the power

[Robbierayy1]

Originally Posted by steve99

Without the addition of flex fuel ethanol sensor the ecu doesnt have any indication of ethanol percent.


All it does is compare the measured afr with the commanded afr if its leaner it adds fuel if its richer it removes fuel using the learned fuel trims.


When you add ethanol it makes car run leaner as you need 30% more ethanol to achieve the same stoicometric burn as petrol.


You get extra power from ethanol in NA car by advancing the ignition timing as ethanol jas a higher octane rating and jence more knock resistant.


When you running a dedicated e85 tune the fueling is increased about 30% and the timing is increased up to 10 degrees in places.


If you reduce the ethanol % outside the 60-90 range then it doent work well and its possible to damage engine.


Eg if you run 50% ethanol you will run way rich as your going to be oitside what the trims can compensate, this can cause issues with lubrication and you will be running way too much timing and you will get consideravle knock, the ecu will attempt to compensate but its getting outside the limits of compensation.

Thank you Steve very much! Your answers have been very helpful and my understanding of the tune and ethanol is much better now! Keep up the great work! I've been running the tune for about 2 weeks and its been amazing especially compared to stock. Everything is good so far and I just wanted to understand how the tune, car, and ethanol work and correlate with each other. You have explained it very well and now I can analyze the data from my car to see if anything is wrong and overall have a better understanding/knowledge about this topic!

[Tor]

Originally Posted by pym19109

Seem like avcs affect MBT of E85 as I have tried.



Red,Blue are Wayne's Rom with pulled 1-2Deg above 6800+rpm to reduce knock

Yellow,Green are using Tor's avcs with original wayne's timing.

Above 5000 rpm torque and hp are significantly different.

You need an absolutely flat road, and you need to do the pulls starting at the same spot. Looks more like you are messuring the bumps in the road as none of these pulls have a curve as would be expected.

You need to do a few pulls on each tune as well, and discard the ones that have a strange progress.

[Toyarzee]

Could anyone help me to understand why cruising and WOT stft and ltft are pretty close to nill, but at idle stft stays low but ltft jumps to 14-16%? Is that typical?

[steve99]

Originally Posted by Toyarzee

Could anyone help me to understand why cruising and WOT stft and ltft are pretty close to nill, but at idle stft stays low but ltft jumps to 14-16%? Is that typical?

large variations in intake air temps at idle and very low air flows at idle make it difficult to scale that section of maf scale.


If you want to reduce that just note the maf volts at idle. then if your seeing +14% in that area add say 8% to maf flow number in those voltage cels or if its -14% remove 8% from maf flow numbers. maybe smooth the adjacent cels by 5%

[Toyarzee]

Originally Posted by steve99

large variations in intake air temps at idle and very low air flows at idle make it difficult to scale that section of maf scale.


If you want to reduce that just note the maf volts at idle. then if your seeing +14% in that area add say 8% to maf flow number in those voltage cels or if its -14% remove 8% from maf flow numbers. maybe smooth the adjacent cels by 5%

Cool, thanks! No real harm in leaving as is I assume? IATs expected to drop when weather settles

[Robbierayy1]

Hey Steve I read back through our posts and may have missed it, but how or is there a way I could check the commanded afr and the measured afr. Can I check with the OFT? Im assuming the commanded on the e70-75 tune would be somewhere between 10.6 - 10.41 based on my calculations. Going back to your example of e50 in a car which made sense to me except for the rich part. If the commanded afr on the tune is 10.6 - 10.41 then shouldn't the e50 in the tank make the car have a lean exhaust since it has an afr of 11.8? The ecu would have to compensate and add fuel to achieve the e70-75 afr ("go rich command") which would in turn show positive fuel trims.