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Thread: 21 Mustang GT 10R80 HELP!!!

  1. #1
    Potential Tuner
    Join Date
    Jul 2019
    Location
    Rittman, OH
    Posts
    4

    21 Mustang GT 10R80 HELP!!!

    Hello everyone, I have a base model 21 GT that does not have the toggle switch to change modes so I decided to try and turn them on via HPtuners. I started with the engine side by switching the use OEM to override and selecting the Drag/Sand mode. Wrote the tune and everything was great. It shifted hard like it was supposed to but I noticed the shifting map was still similar to just the normal mode. So I went into to the Trans portion in HPtuners and looked for anything the was specific to the driver modes. Once I turned everything over to reading everything from the Drag/Sand map I rewrote the the tune. When I started it up the check engine light was on. I scanned it but nothing came back. Once I got on the road it shifted from 1st into 2nd but was stuck in 2nd and it wouldn't even downshift or manually shift. I pulled over and reverted back to the previous tune. Still had the same issues on my way home which was maybe a 1/4 mile away. I got home then put everything back to the original OEM tune. Still has a check engine light with no codes read and it won't shift past 2nd. It also has long delay to go into drive or reverse from a stop and almost wants to spin a little when engaging. Any help would be much appreciated.

    Thanks guys!

  2. #2
    I would recomend to write entire perhaps with the factory file. If not use ford software to set the pcm back to factory.

  3. #3
    Potential Tuner
    Join Date
    Jul 2019
    Location
    Rittman, OH
    Posts
    4
    We ended up figuring it out. Somehow the computer lost the serial numbers from the side of the trans so it didn't know what transmission the car had. We ended up having to use a Ford tool and put the numbers back in. Fixed! I didn't think about a full rewrite which might have also fixed it.