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Thread: Incorrect Gear Ratio PO730

  1. #1

    Incorrect Gear Ratio PO730

    This just popped up on my DTC codes on my Aeroforce gauge a few days ago. Couple of questions on it.

    In HP Tuners, we set it up as 3.29 gears with a drive sprocket ratio of 1.00. Now I have heard some people saying that it needs to be setup with 3.69 gears and leave the sprocket ratio at 1.121 so that it reads correctly and doesn't flash this code.

    Now the weird part is...I don't notice anything out of the ordinary with my transmission, it shifts great, downshifts fine, and doesn't have anything funky going on with it despite this code. Any input on what I need to do would be great...keep in mind this is a brand new rebuilt 4t65e-hd transmission with all new parts. I'm not sure I have the VSS reluctor wheel in there, but my speedo works. Why would it still shift fine with this dtc code?

  2. #2
    Senior Tuner Russ K's Avatar
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  3. #3
    Russ,

    Thanks for the link. So I'm guessing that the new version of HP Tuners does not work to put the sprocket ratio to 1.00. I should change my sprocket ratio back to 1.121 and put in 3.69 gears for my 3.29s. Do that and then clear the codes and go for a drive?

    Just let me know and I'll have my tuner adjust it for me.

  4. #4
    bump....Russ I understand your post but at the same time they still have not corrected this issue in updated HP Tuner versions yet for the sprocket size?

  5. #5
    Potential Tuner
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    Sep 2008
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    Stock 2.93 gearing is 1.0 (GTP), and 3.29 (GT/ComPG) is 1.12, I would assume that 3.69 (minivan) are even higher...1.21 IIRC.

  6. #6
    Tuner in Training
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    Oct 2009
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    Quote Originally Posted by 11SECGTP View Post
    Stock 2.93 gearing is 1.0 (GTP), and 3.29 (GT/ComPG) is 1.12, I would assume that 3.69 (minivan) are even higher...1.21 IIRC.

    Are you saying the 2.93 is somehow baselined at "1.00" instead of the 3.29 like it's supposed to be? That might explain my problem. I have a 2.79 final drive in a customers 4T65E (37/33 sprockets = .89 ratio x 3.05 diff) I have tried about every combo of values.