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Thread: forced open loop??

  1. #1

    forced open loop??

    Under fuel > oxygen sensors is where you can force open look.

    However the little description text seems counter-intuitive

    [ECM] 2529 - O2 Sensor Ready Voltage: If the O2 voltage drops below this value, the O2 Sensor is ready for closed loop. Set low to disable closed loop.

    stock value is 1,795


    As it reads, if the O2 voltage drops below 1795 the O2 sensor is ready for closed loop. Then it says, set low to disable closed loop?

    I use a value of -1795. Closed or open loop?

    In all my scans with a negative O2 value, the PID: fuel system status #1 says CL-normal. I assume that means the car is in closed loop?

    Thanks for helping a nooob!

  2. #2
    Senior Tuner Higgs Boson's Avatar
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    -1795 is how I run open loop full time

  3. #3
    weird, with -1795 my logs still show closed loop active set to "yes"
    closed loop yes.png

    shouldnt it say no, if forced to open loop?

  4. #4
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    Quote Originally Posted by str8dum1 View Post
    weird, with -1795 my logs still show closed loop active set to "yes"
    closed loop yes.png

    shouldnt it say no, if forced to open loop?
    It should, and I've run into the exact issue you have in the past on some cars as well. Maxing out closed loop enable delay [ECM] - 12462 has helped in these cases.

  5. #5
    If i turn off closed loop thru the scanner, that "closed loop active" goes to no, so that makes me think that just setting the O2 sensors to -1795 is not forcing open loop.

    No way to properly tune MAF or SD if not entirely open loop.

  6. #6
    Senior Tuner Higgs Boson's Avatar
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    might be unique to whatever car/operating system you're using. I have never experienced that in hundreds of cars/trucks.

  7. #7
    its a run of the mill 2018 silverado.. closed loop active stays yes with the O2 sensors at -1795.

  8. #8
    Senior Tuner Ben Charles's Avatar
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    For what it’s worth I’m not able to make 17-18 trucks (6.2) to stay in Open loop no matter what I set things too.. haven’t tried 5.3

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  9. #9
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    Quote Originally Posted by Higgs Boson View Post
    might be unique to whatever car/operating system you're using. I have never experienced that in hundreds of cars/trucks.
    My 2015 corvette won't do it between flashes sometimes with identical settings. Weird stuff.

  10. #10
    seems like if i force closed loop to off in the scanner under the options, it changes it to "no" for closed loop active.

    If in open loop, you wouldnt expect to see LTFT and STFT though, correct?


    Quote Originally Posted by Ben Charles View Post
    For what it’s worth I’m not able to make 17-18 trucks (6.2) to stay in Open loop no matter what I set things too.. haven’t tried 5.3

  11. #11
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    Quote Originally Posted by str8dum1 View Post
    seems like if i force closed loop to off in the scanner under the options, it changes it to "no" for closed loop active.

    If in open loop, you wouldnt expect to see LTFT and STFT though, correct?
    That's correct. Just tune part throttle with fuel trims if you continue to have trouble.

  12. #12
    cool, finally gonna get around to installing my wideband this weekend, so def dont need the LTFT and STFT for that.

    Thanks!

  13. #13
    Any update on how to force open loop on some of these Gen V?

  14. #14
    i just use the scanner to force it while logging

  15. #15
    Advanced Tuner Ghostnotes's Avatar
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    So forcing the open loop in the scanner, as in toggling in the scanner bypasses the multipliers DFCO....etc?

    I assumed you still had to set you rediness voltage, power enrich, COT etc not to interfere??
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  16. #16
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    Forcing open loop in the scanner negates the need to set the readiness voltage, but all of the other settings should be corrected unless you just filter them out in the scanner.

  17. #17
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    my 2019 ss wont stay in open loop if I set readiness to a negative. very annoying having to manually force it in the scanner.

  18. #18
    Advanced Tuner Ghostnotes's Avatar
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    Quote Originally Posted by sevinn View Post
    Forcing open loop in the scanner negates the need to set the readiness voltage, but all of the other settings should be corrected unless you just filter them out in the scanner.

    Ok that's what i thought. Made me think for a second that HPT created a master switch lately.....
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  19. #19
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    Thanks for the info! It is April 2021 and I am still using this thread!

  20. #20
    I ended up unplugging the sensors and "No Mil" the codes to force Open Loop on 2018 5.3 Silverado PCM.

    Otherwise no matter what I did the STFT would activate no matter what settings I used under Oxygen Sensors.

    This is in a swapped vehicle with messed up sensors that would read crazy and I had to get the car on the road.