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

[steve99]

As above Kodename47 is correct

just 02 sensor reads residual 02 so it doesnt know difference between petrol or E85.

The romraider defs and even ecutek, most display everything relative to petrol AFR.

that why the AFR tables in a petrol and E85 tune are same when you look at tune.

but the real "afr" is different as kode said above.

when your on petrol 14.7 is 14.7 and displayed as 14.7.

when your on E85 afr will display and log as 14.7 but its rearly 9.7

but lamda is 1 in both cases

[guybo]

And E10 (gas stations around here have 10% ethanol) has a stoich AFR of 14.1 but like Steve says, you'll see your AFR (as read on the CanBus) normalized to 14.7

I have an Autometer AFR gauge on my car and you can set what the Stoich AFR should be, or use 14.7 or just use the lambda instead.
@steve99 thanks, once again for your work on OFT! I use your guides all the time.

[Weigaldo]

I finally made the jump to E85 last night. I filled up the tank, drove around until the trims rose... Pulled over to flash aaand got an error writing. I was like "FFFFFUH" I have a full tank of E85. Turned off the car and back on, then it flashed correctly. Right now my trims are around -7, but I imagine they'll get better with the next tank once the gas concentration decreases.

[bababooey]

i think when you write a new tune, engine has to be off. u can connect tablet while running but can only view the realtime parameters, at least in my experience from my recollection. i just flashed back to petrol for mem day trip to the AR boonies where i dont want the hassle of chasing down a station.

[guybo]

Originally Posted by Weigaldo

I finally made the jump to E85 last night. I filled up the tank, drove around until the trims rose... Pulled over to flash aaand got an error writing. I was like "FFFFFUH" I have a full tank of E85. Turned off the car and back on, then it flashed correctly. Right now my trims are around -7, but I imagine they'll get better with the next tank once the gas concentration decreases.

This is my nightmare when I have to switch to gas or E85 and back!

[Purist]

Do I have this on straight?

The only major fueling difference between open loop 98 and open loop E85 is the change in maximum trim from 4.00% to 40.00%, to allow the LTFT to compensate?

I freaked out when I looked at my OFT E85 open loop map and saw a bunch of 14.7s! Thought I'd been running E85 on a 98 tune!

[carsebuco]

Originally Posted by guybo

This is my nightmare when I have to switch to gas or E85 and back!

Ii doubt having the "wrong" gas in there will ever cause an error during the writing process.

[Purist]

Originally Posted by carsebuco

Ii doubt having the "wrong" gas in there will ever cause an error during the writing process.

I think he might mean getting an error for whatever reason during the writing process and bricking the ECU.

[carsebuco]

Originally Posted by Purist

I think he might mean getting an error for whatever reason during the writing process and bricking the ECU.

Tbh I should have quoted the OP from whom he quoted. He made it seem that he couldn't believe that it failed when his tank was only e85... almost as if it just knew...

But yeah, lately I've been flashing mine left and right trying to decide if I do like v4 better.... But it has never failed on me...

[steve99]

Originally Posted by bababooey

i think when you write a new tune, engine has to be off. u can connect tablet while running but can only view the realtime parameters, at least in my experience from my recollection. i just flashed back to petrol for mem day trip to the AR boonies where i dont want the hassle of chasing down a station.

Flash device needs exclusive access to ecu processor to write new software, so ecu cannot be managining engine during read or write

[steve99]

Originally Posted by Purist

Do I have this on straight?

The only major fueling difference between open loop 98 and open loop E85 is the change in maximum trim from 4.00% to 40.00%, to allow the LTFT to compensate?

I freaked out when I looked at my OFT E85 open loop map and saw a bunch of 14.7s! Thought I'd been running E85 on a 98 tune!

Haha no bit more in it

Check the port injector scaling brz parameter is 30% different to petrol tunes to trick ecu into injecting 30% more fuel.

Also for the diect injection the pressure targets are increased 30% to get that system to inject 30% more fuel to achieve the extra fuelng required.


They keep the ltft max at high vslue to aloow trims to correct for varyinv ethanol content in e85.

The ecu is cslibrated for pertol afr.

The o2 sensors read residual o2 so doesnt know difference between petrol or e85

But when your on e85 stoiceomtery is achieved at about 9.7:1 afr not 14.7, but as ecu still works in petrol afr its interpreted as 14.7 but in reality its 9.7:1

[khrono]

Hi all,

I was not able to find any updates for fixing cold start issues on the new v4.03 e85 tune on OFT.

I was running the old v2 tunes for the last 30k miles or so and used the changes steve99 suggested for pulse width modifications and it worked beautifully for basically all starts here in the bay area without a problem. Maybe only once or twice when it was really cold like 40 degrees did it take more than once to turn over.

With the new v4.03 files I am enjoying greater oem feel if that makes sense. Before letting off the gas at high RPMs produced a strong lurch or lunge. Now it drives normally with power delivery more smooth. The problem I am having is with the regular e85 stg2 + I had to turn over maybe 3-5 times in the morning when it is 59 Degrees F.

I added the pulse width mods for cold start from the V2, but it is not a direct crossover as some tables do not have the same rows. The car almost turns over now in the morning and usually does so after the second attempt, but I was wondering if anyone knew how to tweak the v4.03 to get the similar results as before. I really want to have to only push start once. Thanks!

MY '15 BRZ.

[Chamber27]

M

Originally Posted by steve99

As above Kodename47 is correct

just 02 sensor reads residual 02 so it doesnt know difference between petrol or E85.

The romraider defs and even ecutek, most display everything relative to petrol AFR.

that why the AFR tables in a petrol and E85 tune are same when you look at tune.

but the real "afr" is different as kode said above.

when your on petrol 14.7 is 14.7 and displayed as 14.7.

when your on E85 afr will display and log as 14.7 but its rearly 9.7

but lamda is 1 in both cases

Sent from my SM-G955U using Tapatalk

[NARFALICIOUS]

I know it's probably somewhere in here, but I want to ask. I read a lot of the thread.

- I ran 5-7 miles past the low fuel light
- Filled up 4 gallons or so of E85(all the $ I had, didn't have my debit card on me)
- According to the station pump, no less than 70%
- Drove a couple miles, stayed under 3500RPM, Loaded the tune (E85 Stage 2 UEL 2.076) when it started consistently showing +15% LTFT
- Drove about 6 miles, filled up to a full tank.
- Been monitoring and after 15 more miles, still at - 4.81% LTFT at idle, have not had too much driving over 3500RPM, and it only went up to 4000RPM a couple shifts.




Do I need to keep driving?

Thanks.