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Thread: Throttle Cracker Tuning Question {B4309}

  1. #101
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    Factory LS6 intake with a factory cable driven throttle body. Nothing crazy.

    Sent from my Pixel 3 using Tapatalk

  2. #102
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    Quote Originally Posted by pinstripebob View Post
    Frames 4,496-5,205 show some of this bucking, it is mostly very light with a few seconds of the gnarly stuff. That speed has been pretty consistent for bucking, but with this last tune it's definitely better.
    Where that gnarly stuff happens, your fueling is really good and spark is steady. The bucking should be gone... the fact that it's not is telling me that your flywheel is too light for that cam.


    Quote Originally Posted by pinstripebob View Post
    If need me to do anything or try anything, just say the word! I think we're near the end of our road though which is awesome!
    Yeah, we are near the end of the road. I will get you to try one last update. This update is purely 'experimental'.... it's something I've never tried before, but I remember a few years ago someone claiming that it worked for him... so I figure it's worth a shot.
    Last edited by statesman; May 13th, 2019 at 08:07 AM.

  3. #103
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    These last couple weeks have been pretty hectic for me, but I got some good data. I've attached two logs to this post, the first from May 14th is with your updates, the second from May 22nd is after a few of my experiments modifying the 68-140C values you had adjusted. Currently, I have them set to 5.83594, with values 32, 44, and 56C linearly interpolated.

    The log from May 14th did not seem to change things much, subjectively. I tried changing these values to stock and up from there, found what seemed to be a range of values where bucking seemed to become less severe and less frequent. I don't think I've found the sweet spot, but I do think I'm in the ballpark. Again that's my butt dyno talking, not my logs' data.

    There's a small town I drive through that has a low speed limit, and it normally results in a bit of bucking. Using that as a consistent area for comparing data, I'm inclined to say the later 5.83594 value reduces bucking compared to the earlier 3.50000 value. LTFT average about the same, STFT average a little tighter with the later timing. Of course now that I'm typing this out I wish I had gotten some data within a few percent of 3.5 as well.

    These spots are shown in the logs as follows:
    May 14th, slow town, frames 4,329-5,192
    May 22nd, slow town, frames 4,239-5,140

    With more time, I might be able to find the sweet spot, but it's a pretty iterative process that may not warrant many logs' worth of review for you. I imagine I'm probably ready to be cut free, this car does have a lightweight aluminum flywheel and a decent amount of overlap with the cam. For reference, the flywheel is Fidanza part number FID198171 and the cam is Summit part number SUM-8700. It's definitely possible the lighter flywheel is allowing more bucking, and the rest of the drivetrain does seem to have a bit of slop in it which would let all the moving parts clang around rather than damp the movement.

    Let me know what you think, your help getting me here has been very helpful and I'm much appreciative of it! Below are the two logs, if you need anything else just say the word!

    Logs:
    GTO May 22 2019 IBC to home.efi
    GTO May 14 2019 IBC to home.efi

  4. #104
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    Quote Originally Posted by pinstripebob View Post
    I imagine I'm probably ready to be cut free, this car does have a lightweight aluminum flywheel and a decent amount of overlap with the cam. For reference, the flywheel is Fidanza part number FID198171 and the cam is Summit part number SUM-8700. It's definitely possible the lighter flywheel is allowing more bucking, and the rest of the drivetrain does seem to have a bit of slop in it which would let all the moving parts clang around rather than damp the movement.
    Yep, you're ready to be cut free. I've done all that I can... but with that lightweight aluminum flywheel you're always going to get some bucking. You can never completely tune out a physical issue. The last tune was experimental, so go back to the previous tune (which was number 20) and use that as your base tune. I know you've been itching to do your own tuning, so now it's time for you to have some fun. Play around with the tune and you might be able to find a sweet spot. If your changes make things worse, go straight back to that base tune and start over.

    Now, to get back to your original question about the throttle cracker. This table is only there to adjust the 'feel' of how much deceleration you get when you let off the gas pedal. When you use lower values in that table, you get a more severe deceleration. Zero that table and the deceleration will feel too harsh for most people. Go too high in that table and you'll get a cruise control effect where you don't decelerate at all. So play with that table to get a level of deceleration which you're happy with... but don't expect that table to do anything for your bucking.

    You know which tables I've spent the most amount of effort on.... now I can't stop you playing with those tables, but I would advise you to leave them alone.

    Good luck and happy tuning.

  5. #105
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    I've already screwed everything up, I changed pretty much everything and it barely runs!

    Just kidding, I've swapped back to the previous and I'll do some tweaking to see if I can't squeeze the last little bit of bucking out of it. I can handle a bit of bucking, but playing with the tune is super addictive.

    Good to know on the throttle cracker table! It definitely helps to see what tables really affect how the engine/car behave. I highly doubt I'll touch any of the tables you spent a lot of time on, there's no reason for me to basically undo what's been done and given good results.

    Thank you very much for all the help! Cheers!

  6. #106
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    lol on your first sentence

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