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Thread: JTEC 4.0 closed to open loop switch?

  1. #1
    Tuner in Training
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    May 2020
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    JTEC 4.0 closed to open loop switch?

    Hey guys...

    So I'm still a bit green and poking my way through dialing in this jeep. Open loop is just about right and now I'm wanting to bring closed loop back into the equation. I'm trying to figure out what commands the ecu to go into open loop. Right now, I have closed loop disabled all together.

    The setup on this jeep builds boost easily under light load on hills and such... so I would like it to go into open loop without going WOT.

    Is power enrichment using the open loop base table? Would I just alter the MAP threshold for power enrichment?

    Here is the stock file from the Jeep. I noticed that with the latest editor update, I can disable closed loop at certain RPM now which sorta helps... but not completely. It would be nice if it could be done via throttle position or MAP value.

    Thanks

    Stock.hpt

  2. #2
    There always seems to be a delay when you try to force open loop at a specified pressure. I have not been able to figure out how to force it open as soon as it hits the specified KPA. If someone can show me that, I can remove the rpm based open loop and my tune would be tits.
    2004 jeep LJ
    Stock supercharged 4.0, 36lb injectors, 62mm bbk throttle body.
    2017 f250 6.7 Diesel
    2020 Explorer 2.3 ecoboost

  3. #3
    Tuner in Training
    Join Date
    May 2020
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    Quote Originally Posted by jbee View Post
    There always seems to be a delay when you try to force open loop at a specified pressure. I have not been able to figure out how to force it open as soon as it hits the specified KPA. If someone can show me that, I can remove the rpm based open loop and my tune would be tits.
    After playing with it for a day, I decided to leave it locked in open loop. I was having weird lean spikes and odd issues when in closed loop. Didn't matter what I did, it would sometimes go open loop at 2 psi.. sometimes 8psi... sometimes before boost. Too erratic.

    Went back to closed loop.. leaned it out a bit coming into boost (now at 14.5 at 0 vacuum.. ~12.5 by 5psi... anything over 5psi sits at 11.5:1). Also went back in and put a lot of timing back in it and it drives sooo much better now. I disabled all the adders and bs... it follows the base fuel table and thats it. Has a lean idle and somewhat lean cruise (~15:1)... throttle response is great.. cold start is great. I also disabled all the adders for timing and have it only running off the base spark table.

    This may not be the "right" way.. but it's working great and I'm happy with it.

  4. #4
    I have found having the closed loop disable at 2k and re-enable at 1200 along with it "disabling" at 0* vacuum works well. It allows your idle to go to closed loop and adjust as needed for AC kicking on and off and also for colder weather startups. Once it kicks off at 2k rpm it usually will not kick back on(closed loop) until back under the set rpm for a few seconds.
    2004 jeep LJ
    Stock supercharged 4.0, 36lb injectors, 62mm bbk throttle body.
    2017 f250 6.7 Diesel
    2020 Explorer 2.3 ecoboost

  5. #5
    Tuner in Training
    Join Date
    May 2020
    Posts
    45
    Quote Originally Posted by jbee View Post
    I have found having the closed loop disable at 2k and re-enable at 1200 along with it "disabling" at 0* vacuum works well. It allows your idle to go to closed loop and adjust as needed for AC kicking on and off and also for colder weather startups. Once it kicks off at 2k rpm it usually will not kick back on(closed loop) until back under the set rpm for a few seconds.
    May give that a try. It would likely keep cruise a/f on point as well.