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Thread: GT500 Closed Loop Fault

  1. 10-09-2018 #1
    mitch.duncan88
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    GT500 Closed Loop Fault

    I have a customer who swapped a 5.4L engine into there 2014 GT500 with the 5.8 blower and a cobra jet TB and stock 2014 GT500 injectors. Ive set everything in the tune appropriately for it to run and drive fine in open loop but as soon as i allow closed loop it goes into CLFault and the STFT's go crazy. Ive attached 2 logs, one of CL and one in OL. everything else tunes in fine as long as i stay in OL. Any ideas would be appreciated. Do i need the 5.2L ecu? replaced both 02's already.GT500 Closed Loop Issue.hplGT500 Open Loop Idle.hpl
    Last edited by mitch.duncan88; 10-09-2018 at 01:53 PM.
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  2. 10-09-2018 #2
    MRRPMBRP
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    Both O2's?
    It has, or should have 4 O2's, two wide bands, and two narrow bands.

    Are you meaning he installed a 5.4L motor? Or did he install a 5.2 Voodoo motor?

    ECU doesn't cars what displacement it is, it will run fine after the tune is straightened out, or whatever the problem is.

    How are you allowing it to go into closed loop?
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  3. 10-09-2018 #3
    mitch.duncan88
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    Sorry, 5.4 my fat fingers. It came in with cat deletes and rear o2s disabled by previous tuner. Replaced both front widebands. Im disabling CL by raising "CL o2 sensor temp" to 4000 which keeps it in OLStability.
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  4. 10-09-2018 #4
    MRRPMBRP
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    I have always been told that the ecu uses the rear nb O2's to calibrate the front wb O2's. Not sure it'll work disabling them.

    On your log, one O2 stft wants to add, one subtract, is that the problem you're asking about?
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  5. 10-09-2018 #5
    mitch.duncan88
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    yup thats the issue. once it goes in CL the fuel trims swing as a huge mismatch causing the car to run horribly. Ive heard similar things about the narrowbands on other vehicles so guess ill install some and re-enable. See how that goes.
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  6. 10-09-2018 #6
    wayno
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    o2 plugs reversed?
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  7. 10-09-2018 #7
    dsblk93gt
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    You shouldn't have to change much going from the 5.8 to the 5.4, sounds like you have wiring issues with o2 like mentioned
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  8. 10-09-2018 #8
    Plentipower
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    Quote Originally Posted by wayno View Post
    o2 plugs reversed?
    ^^^This^^^
    Only time ive ever seen fuel trims go complete opposites of each other. Upstream o2 harnessed are plugged into the wrong banks. It happens a lot when engines are swapped or clutches are replaced. Seen it many times before.
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  9. 10-10-2018 #9
    mitch.duncan88
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    You guys got it. O2 reversed. Got it on a lift today and swapped them over, BAM 2% trims happy as can be. Thanks for everyones help. Something to commit to memory for me now.
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