Open Source Flex Fuel

[FR-S2GT86]

Originally Posted by mrjj

It could be, but it's probably not. Do we even know if there are any unused input pins (on the chip, not the connector)?
Here is a good start guide for anyone who wants to give it a try:
https://www.romraider.com/forum/viewtopic.php?t=6303

If I had any coding skills at all, which unfortunately I don’t, I would be willing to try. It looks like ztan here has all of the experience in disassembling the ECU and mapping the circuitry out already and writing the new code. There are extra male pins entering in the ECU. In fact, there are pins in every single space, but the harnesses that connect to them don’t have the female pins or wires to connect anything to them. I have a spare ECU that I bought but I wouldn’t know what to look for when I open it up. If we could use ztan’s research, we might be able to make some sort of progress.

[FR-S2GT86]

Originally Posted by churchx

What "existing code"? "as easy"?
People have access only to binary firmware dump from ecu, then there goes low level disassembling, no documentation, no comments, no source code and alike, one has to do lot of guessing, going by hunch, trial & error (including results like bricking ecu, or crashing), "coding" is in low level, especially more so if you want to code something extra, most of "tuning" happens to be by tweaking values in some found tables, not adjusting code that works with those. It was major PITA to add extra functionality/custom codepaths for E85/forced induction/LC/FFS and alike, a bit better for paid team of devs @EcuTek, much harder for single enthuasists doing for free at limited off-work time such enormous low-level work that requires much higher skillset then generic coding in higher level languages if one had access to original source code (most probably no-one outside toyota/subaru ever will, to not ease tampering with firmware for legal reasons, including emissions certification and such).
Have you ever done yourself "easy" coding in assembly for undocumented existing binary firmware that works on undocumented hardware set (including mentioned extra input/output signal pins)?

I see that as a challenge, not an obstacle.

[dholloway543]

Im pretty fluent in code, Mostly x86. For anyone trying to understand the concept of a computer running assembly I would suggest first learning any program language then going here.


https://wiki.osdev.org/Expanded_Main_Page

[FR-S2GT86]

Originally Posted by dholloway543

Im pretty fluent in code, Mostly x86. For anyone trying to understand the concept of a computer running assembly I would suggest first learning any program language then going here.


https://wiki.osdev.org/Expanded_Main_Page

Unfortunately, my current chosen career path does not afford me the time to learn coding at the moment. I travel and I am away from home for between eight and 16 hours a day, five days a week.

I do however, have experience in the installation of aftermarket mobile electronics such as alarm systems, remote starts, audio systems, and cruise controls. I plan to contribute these skills to this board whenever I can.

[steve99]

Originally Posted by FR-S2GT86

I see that as a challenge, not an obstacle.

Yes its a chalenge, unfortunatly the number of people with the skill, dedication, time ( your looking at hundreds of hours even for a skilled person) and who probably own a brz\86 and want a carb legal flex tune who would do that sort of work for little or no return will be an extremely small set of people.


If you want to progress that id suggest that you contact ECUTEK and ask if its possible. They will probably want to know how big the market would be for carb legal flex tunes before committing resources to the project i would think.

[steve99]

Originally Posted by FR-S2GT86

I’ve been wondering if anybody has the coding skills to remap one of the unused pins of the ECU for use as the ethanol content sensor input so that we here in the US can get a flex-fuel kit that has the potential to be CARB compliant. Instead of substituting the ethanol sensor for the rear O2 sensor or the evap pressure sensor, which automatically disqualifies the modification from being compliant, to adding the additional sensor where there wasn’t one before. I would take this on personally if I had coding skills, or would be willing to supply someone with a spare ECU for research and development and would gladly help to pay to get this project started. Would anyone else here be interested in this?

Ok if you go ecutek latest racerom version 11


It allows the flex sensor input to be the rear 02, evap pressure or the MAF ie mas air flow sensor.


Now you usually need maf for metering incomming aor to engine but in ecutek its also possible to use speed density method . Speed density uses the MAP ie pressure sensor and intake air temp to determine air flow in engine


So theroeticly you could repurpose maf sensor to flex, and use speed density tune method This would leave both the evap amd rear 02 active for emmissions tests.


Now the downside may be speed density may make throttle response a little slow at low rpm, and it may or may not allow tuner to fuel engine well enough to pass emmissions standards, who knows but its theoretly possible with ecutek at present

[ojuniour]

Wait so ecuTek for 2017+ doesn't really require the evap pin? You have the option. To go for the O2 sensor also?

Sent from my ONEPLUS A6013 using Tapatalk

[steve99]

Originally Posted by ojuniour

Wait so ecuTek for 2017+ doesn't really require the evap pin? You have the option. To go for the O2 sensor also?

Sent from my ONEPLUS A6013 using Tapatalk

Yes ecutek can use rear 02 or evap connect flex kits on all models incliding 2017+


Opensource only supports evap amd only pre 2017

[FR-S2GT86]

Originally Posted by steve99

Ok if you go ecutek latest racerom version 11


It allows the flex sensor input to be the rear 02, evap pressure or the MAF ie mas air flow sensor.


Now you usually need maf for metering incomming aor to engine but in ecutek its also possible to use speed density method . Speed density uses the MAP ie pressure sensor and intake air temp to determine air flow in engine


So theroeticly you could repurpose maf sensor to flex, and use speed density tune method This would leave both the evap amd rear 02 active for emmissions tests.


Now the downside may be speed density may make throttle response a little slow at low rpm, and it may or may not allow tuner to fuel engine well enough to pass emmissions standards, who knows but its theoretly possible with ecutek at present

So Ecutek already has a third input option. That’s good news. I have the Ecutek OBD2 hardware, software and license already, but not the racerom package yet. So far I’ve only used Ecutek to get a rom dump for my ECU to send to Harrop for my supercharger tune, as well as for the rom dump for the spare ECU that I purchased. I’ve already installed the flex fuel sensor in my fuel line and have the ethanol content analyzer and gauge ready to connect, but was waiting for new options in connecting it all up before I get a flex fuel tune. This third input option looks promising, but I will wait until all the bugs have been worked out. I may go with the O2 sensor input temporarily to get the flex kit operational and later on swap to the MAF sensor input for the permanent mod.

Thanks steve99 for digging into this a little bit more. It’s much appreciated.

[tomm.brz]

latest version of ecutek seems the 11.1
stable enough for me

[ojuniour]

Originally Posted by steve99

Yes ecutek can use rear 02 or evap connect flex kits on all models incliding 2017+


Opensource only supports evap amd only pre 2017

ok So I built my own flex fuel.. which i was originally going to connect to the evap (which sends voltage signal depending on E-content).
Do you think I can just tap the O2 sensor or does that requires a different voltage gauge?

[steve99]

Originally Posted by ojuniour

ok So I built my own flex fuel.. which i was originally going to connect to the evap (which sends voltage signal depending on E-content).
Do you think I can just tap the O2 sensor or does that requires a different voltage gauge?

Voltage range is same rear 02 or evap, howver you will need ecutek to use rear 02 input for flex , unless your rewriting ecu code

[ojuniour]

Originally Posted by steve99

Voltage range is same rear 02 or evap, howver you will need ecutek to use rear 02 input for flex , unless your rewriting ecu code

Yea I'm gonna be using ecuTek.
I went with the 0.5 - 4.5v range. So I just need to tell them that range
and I also believe the rear 02 sensor has three wires (White, Black and Blue)..
Do you know which one receive and send the voltage? ( I believe black would be the ground)
Thank you.

[tomm.brz]

rear o2 has 4 wires, 2 on top are for heater, just leave disconnected
the blue wire on bottom is the positive if I remember correctly

To then scale and use the sensor on any input port, you need a tuner to do it, or to buy a Racerom license to be allocated to your kit