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Thread: Falls out of closed loop

  1. #1

    Falls out of closed loop

    2006 Z06, pretty big cam and headers, car will go into closed loop and then come back out of closed loop for a bit and then back in. Sometimes it will fall out several times before staying in closed loop for the rest of the drive. What?s causing this? I?m assuming the o2s aren?t hot enough but how does the pcm know? O2s are oscillating fine when it falls out, typically cruising under light load is when it goes into open loop. Are there parameters i can change to help it stay in closed loop?

    If you look at about the halfway point of this log, you can see it in open loop and switch back and forth a few times. Car was warmed up already at this point as well. Thanks!

    ST 3.hpt

    ST 3 d1.hpl
    Last edited by Blue-Z; 06-29-2019 at 09:38 AM.

  2. #2
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  3. #3
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  4. #4
    Tune and log posted in first post, thanks!

  5. #5
    Tuning Addict 5FDP's Avatar
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    You didn't disable the catalyst test and the post o2 sensor test.

    The computer is going into a test mode, it will pull it self out of closed loop doing this. You can even watch as your commanded AFR goes from 14.68 to like 15.9, then down to 13.6 and back to stoich/closed loop.

    Do this and your problem should stop forever.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  6. #6
    Thank you very much!!! Greatly appreciated!!!!!