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Thread: Disable/limit ethanol sensing on 2012 Tundra

  1. #1
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    Disable/limit ethanol sensing on 2012 Tundra

    I am attempting to disable the ethanol sensing on the 2012 Tundra 5.7 3UR-FBE. I have sent in 2 requests to HP Tuners and have not received anything back yet except they "will have the engineers take a look."

    The reason we need to disable ethanol sensing is the Tundra computer when it sees anything lean it assumes ethanol and the ethanol count goes up but never goes back down. When this happens the ECU commands more fuel the higher the assumed ethanol. regardless of how much ethanol is really in there. The other kicker is we are running natural gas most of the time. I do not have any log files at this time but will in the near future. The truck and tune is stock up to this point. From what I understand every 5 key cycles the ECU will perform a check to determine ethanol. I have the owner of the vehicle to pull and reinsert the wire from the gasoline level sensor to manually reset the ethanol sensing and drive on gasoline until the ethanol check is complete (wait 3 minutes idling, drive 3 miles, under 3K RPM) then he can drive on natural gas again.

    I have tried tuning the natural gas to be rich but natural gas does not perform well rich. This issue is the same on 100% gasoline without using the natural gas.

    The stock file is attached

    Thanks for any help. It is greatly appreciated.

    Louis
    Attached Files Attached Files

  2. #2
    yesterday i was reading the fsm to figure out how the system works it has 2 fuel regulator one in fuel assembly that is 43psi fixed for low pressure and on the fuel rail the fuel pressure is 58psi,

    there is a pressure switch valve on top of the gas tank that bypass the internal regulator this removes the 43psi restriction, and then the fuel rail limits to 58.

    the fuel pump control has 3 speed instead of 2, idle/low/high pressure.

    so you have couple of choices i think on the tune you can try making the injector constant high pressure value to match the injector constant low pressure.

    rewiring the pressure switch valve to only work on low pressure mode.

    replacing the rail pressure with a 43 psi one which i think the standard tundra uses.

    keep in mind those choices doesnt take into consideration other issues like ethanol timing map and torque related algorithm so be-careful

    EDIT: i think making inj const to match low pressure would make it richer, it should be even smaller to be leaner with higher fuel pressure
    Last edited by QTR FMS; 07-31-2020 at 11:51 AM.

  3. #3
    https://parts.olathetoyota.com/auto-...omponents-scat

    77020-0C082 Fuel Pump Assembly 26 GALLON, 5.7 LITER, W/ O FLEX FUEL
    77020-0C120 Fuel Pump Assembly 26 GALLON, 5.7 LITER, W/ FLEX FUEL

    77020-0C160 Fuel Pump Assembly 38 GALLON, W/ O FLEX FUEL
    77020-0C170 Fuel Pump Assembly 38 GALLON, W/ FLEX FUEL

    23280-38091 Fuel Injection Pressure Regulator < i believe this is non-flexfuel
    23280-38041 Fuel Pressure Regulator TUNDRA; 5.7L; W/ FLEX FUEL

  4. #4
    Screenshot (43).png

    i think i found an easier way, there is a relay called F/PMP VSV that control the fuel regulators if you remove the relay this should make it work in one mode, not sure which, you could try to hot wire the relay connector and see what happens,

    once you set the relay to work on 43psi mode you can change the tune to make the inj const high the same value as inj const

  5. #5
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    Thank you so much for this information. I talked with the owner a couple days ago and he said the issue is not as bad when ambient is 80+ but when fall and winter hit it becomes an issue. On Chevy trucks with ethanol we put an emulator on the intake air temp sensor to show 30% lower temps which I assume will add a little more fuel to offset the assumed more dense air. This helps on Chevy but not the Toyotas.

  6. #6
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    Quote Originally Posted by QTR FMS View Post
    Screenshot (43).png

    i think i found an easier way, there is a relay called F/PMP VSV that control the fuel regulators if you remove the relay this should make it work in one mode, not sure which, you could try to hot wire the relay connector and see what happens,

    once you set the relay to work on 43psi mode you can change the tune to make the inj const high the same value as inj const
    Nice...That's even better. I will give that a shot

  7. #7
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    Quote Originally Posted by loubum View Post
    Nice...That's even better. I will give that a shot
    Did the relay work for you

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    Not yet, I will pay results when the customer returns to try the relay

  9. #9
    Quote Originally Posted by Lathan601 View Post
    Did the relay work for you
    i tried it on @korbiams tundra and it works when you remove the fuse you disable the flexfuel, and when you hotwire it you get flexfuel mode all the time which is useful when using external boost reference regulator.

  10. #10
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    Quote Originally Posted by QTR FMS View Post
    i tried it on @korbiams tundra and it works when you remove the fuse you disable the flexfuel, and when you hotwire it you get flexfuel mode all the time which is useful when using external boost reference regulator.
    Very good. Thanks for the feedback

  11. #11
    Quote Originally Posted by 4firemandan View Post
    Hey guys.

    I have a 2016 FFV supercharged.

    I'm having the same issues in that it keeps learning ethanol content despite my best efforts.

    I read this and was super stoked to pull that relay and solve the issues... But just filled up and she enough it's still calculating eth content, even with the VSC FFV relay pulled.

    Anyone find a way to completely kill the eth calculating?
    copy your injector constant to injector constant high, same thing with the inverse, this should fix the fuel trim issue, this wont disable the ethanol content so make sure you reset it through techstream.

  12. #12
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    Quote Originally Posted by QTR FMS View Post
    copy your injector constant to injector constant high, same thing with the inverse, this should fix the fuel trim issue, this wont disable the ethanol content so make sure you reset it through techstream.
    Thanks for the reply.

    I have 650s so I'm running different constant and inverse...

    Multiplied inverse and divided the constant by the same percentage and yeah, the max and constant are equal.

    I also pulled that ffv relay but I still get it calculating ethanol any time or sees positive fuel trims following a fuel up or ecm flash.

    Any ideas what I'm missing?

  13. #13
    Quote Originally Posted by 4firemandan View Post
    Thanks for the reply.

    I have 650s so I'm running different constant and inverse...

    Multiplied inverse and divided the constant by the same percentage and yeah, the max and constant are equal.

    I also pulled that ffv relay but I still get it calculating ethanol any time or sees positive fuel trims following a fuel up or ecm flash.

    Any ideas what I'm missing?
    the calculated ethanol will still be active when it sees positive fuel trim but i believe it shouldnt effect the tune as you have disabled its correction methods.

  14. #14
    Quote Originally Posted by 4firemandan View Post
    Yeah, it still does.

    It's in the tables that we can't access unfortunately.

    I've actually permanently removed the low pressure return line so the fuel is forced to only go to the rail where the 60 psi regulator is.

    I replaced that with an adjustable boost referenced one...
    And I added a MSD boost a pump, so any voltage change that would happen under low/high mode is now negated...
    My pump gets 14v until I see 5psi when it gets an extra 4v.

    All of this fixed my lean conditions by great amounts.. but then I've day the truck absolutely fell on its face under heavy accel.

    After much problem solving I found that I was at 30% eth.

    I wiped that to 0 with a TS and it ran amazing again.

    Next fuel up...5% eth reading... Falling on face wide open...

    Wiped ethanol with TS... Running great again.

    It seems that with ANY ethanol it begins referencing charts that we don't have access to that are greatly different.

    I'm guessing probably injector multiplier related.. otherwise there wouldn't be such huge changes.

    If I were running regular size injectors maybe it would be ok... But unfortunately, ANY ethanol reading greatly changes WOT performance.
    interesting, we have tested it on @korbiams tundra and we had no issue.

    if you are using external regulator you should make sure F/PMP vsv is always on with ignition this could be a reason why its acting out.

    another thing you can do is disable closed loop if F/PMP didnt work for you, or make your fuel trim negative -5%

    do you know what is the air fuel ratio when your ethanol content change?

  15. #15
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    Ok. So how would I make sure that the F/Pmp vsv is always on? Ground out that one tab ( the one that's actively grounded when in high flow mode?) This was a trick I'd seen on the Facebook page and have that setup to do.. I used it previously before all the upgrades I did, but it's disconnected currently)

    Also, how could I disable closed loop? I didn't know we could.

    And the trims being -5. That's the tricky part. I actually did this a while back....thought if I could get LTFT there it would be fine... Turns out it uses SHORT term trims to b calculate ethanol.

    When I fattened the tune and had negative LTFT it resulted in more positive STFT which actually gave me MORE ethanol content. At one point I had -20s LTFTs and it was saying I had 85 percent ethanol! Lol

    Lately I've been playing with tuning the idle and cruise slightly lean to get positive LTFT with slightly negative STFT.

    That's been mildly successful... +15 LTFT gives me anywhere from +2 to -5 (ballpark) STFT. I've had 3 fill ups where it's bounced around 0...2, 5...8..11% eth content in the different cells as rpm and load change, but the last 3 fill ups all eventually locked in at 0.

    If I could get it to run good with minimum ethanol I wouldn't care.

    I'm definitely going to try what you mentioned.
    Last edited by 4firemandan; 01-07-2021 at 09:31 PM.

  16. #16
    Quote Originally Posted by 4firemandan View Post
    Ok. So how would I make sure that the F/Pmp vsv is always on? Ground out that one tab ( the one that's actively grounded when in high flow mode?) This was a trick I'd seen on the Facebook page and have that setup to do.. I used it previously before all the upgrades I did, but it's disconnected currently)

    Also, how could I disable closed loop? I didn't know we could.

    And the trims being -5. That's the tricky part. I actually did this a while back....thought if I could get LTFT there it would be fine... Turns out it uses SHORT term trims to b calculate ethanol.

    When I fattened the tune and had negative LTFT it resulted in more positive STFT which actually gave me MORE ethanol content. At one point I had -20s LTFTs and it was saying I had 85 percent ethanol! Lol

    Lately I've been playing with tuning the idle and cruise slightly lean to get positive LTFT with slightly negative STFT.

    That's been mildly successful... +15 LTFT gives me anywhere from +2 to -5 (ballpark) STFT. I've had 3 fill ups where it's bounced around 0...2, 5...8..11% eth content in the different cells as rpm and load change, but the last 3 fill ups all eventually locked in at 0.

    If I could get it to run good with minimum ethanol I wouldn't care.

    I'm definitely going to try what you mentioned.
    yes its the ground wire, when we tried it we used jumper wire to test if it would work and it did, keep it mind the efi No2 fuse is constant 12v not ignition so you might need to find different power source so you don't drain your battery on the long term.

    there is also tester relays that have switch on top this can be helpful if you dont want to do the wirirng but you have to manual switch it on and off every time, or you could use a jumper wire and connect it to a ignition source directly.

    to disable the closed loop you raise the ect (247f) vs startup ect in the oxygen sensor tab, i prefer to disable it any way to have more consistent wot.

  17. #17
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    Screenshot_20200318-195501_Facebook.jpgScreenshot_20210108-061922.png

    So I think I'm close to understanding what you did with the relay but not completely getting it.

    I just ran a constant ground to *I think* pin #3. So it's ALWAYS grounded.(it's been a while)

    You actually ran 12v power to it? Same pin?

    I remember testing by watching fuel trims (after grounding they went more negative)...and I could also hear a click from the FFV switching solenoid when I touched the wire to ground (truck in "on" but not engine running).

    I could just reconnect it to a ground and try again... Currently just pulled the whole relay hoping it would disable FFV (ethanol learning) but no luck.


    So is what I did different than what you're saying? Or same end result, different methid?...

    what exactly did you do with the 12v ignition source and how can I test to be sure I did this correct?

    Thanks for the open loop tip too!
    Last edited by 4firemandan; 01-08-2021 at 05:30 AM.

  18. #18
    Quote Originally Posted by 4firemandan View Post
    Screenshot_20200318-195501_Facebook.jpgScreenshot_20210108-061922.png

    So I think I'm close to understanding what you did with the relay but not completely getting it.

    I just ran a constant ground to *I think* pin #3. So it's ALWAYS grounded.(it's been a while)

    You actually ran 12v power to it? Same pin?

    I remember testing by watching fuel trims (after grounding they went more negative)...and I could also hear a click from the FFV switching solenoid when I touched the wire to ground (truck in "on" but not engine running).

    I could just reconnect it to a ground and try again... Currently just pulled the whole relay hoping it would disable FFV (ethanol learning) but no luck.


    So is what I did different than what you're saying? Or same end result, different methid?...

    what exactly did you do with the 12v ignition source and how can I test to be sure I did this correct?

    Thanks for the open loop tip too!
    we ran a jump wire between pin 5 and pin 3 to bypass the relay, which is a temporary solution.

    you have to ground pin 1 not pin 3 as its the one from the ecu or do as the above both give the same result.

    pin 2 and 5 are coming from the battery directly so the solenoid will always be on and this can drain the battery.




    the reason your fuel trim gets negative is because you are increasing the fuel pressure so you might need to adjust your maf later.

  19. #19
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    Quote Originally Posted by QTR FMS View Post
    we ran a jump wire between pin 5 and pin 3 to bypass the relay, which is a temporary solution.

    you have to ground pin 1 not pin 3 as its the one from the ecu or do as the above both give the same result.

    pin 2 and 5 are coming from the battery directly so the solenoid will always be on and this can drain the battery.




    the reason your fuel trim gets negative is because you are increasing the fuel pressure so you might need to adjust your maf later.
    Gotcha. So is the diagram in the orientation of looking down on the relay? or as from the bottom?

    When you look at the picture, the one I grounded was the one most close to the bottom right(closest to the drivers headlight. Underneath "Japan" on the top).

    I was saying my trims changed confirming it was working, now using the 60psi FPR. So it seems like i did it .. just want to be sure.

    Im going to reinstall the grounded relay and then try to get ethanol to lock in somewhere in the 2-15 range and do some runs.. see if that alleviates the issues I was having.

    Thanks again for the help!

    Please LMK if you think I missed something.

  20. #20
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    how do i go about posting a log to possible get some advise on?
    Last edited by bj-indy; 04-06-2021 at 07:00 PM.