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Thread: Cadillac ATS - LTG Tuning - Exhaust Crackle

  1. #1
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    Cadillac ATS - LTG Tuning - Exhaust Crackle

    Hey guys, long-time lurker, first time poster.

    Been playing with the ATS (2.0L Performance, manual) for a year now after years of tuning Saabs (their old Trionic systems). The methods of engine management have come a long way since the '90s.

    Anyway, attached is my tune. I can see ~35 lb/min at the MAF with no knock or misfiring. Finally pretty happy with it, car runs quick and smooth and once I figured to turn off torque shaping the drivability got much better. Was also great to realize you can actually make power above 5500rpm, this will run smooth to 6800rpm without running out of breath. Having a lot more fun now, the engine was such a wet paper bag before. I should probably go through and write an explanation for all the changes to give something back to the community, but that's for another day.

    One thing I'd really love to learn to do - dial in some light exhaust crackle. I've been doing some reading on this, but can't find anything directly applicable yet. Seems there are things that can be done with DFCO and the Main Spark Advance (and likely the Spark Minimum) tables. Am I close? Would love some guidance here if anyone has ideas. Not looking for Jag F-Type level crackling, but a nice noise during throttle lift would be killer.

    Thanks in advance, and thanks to all those who have shared their tunes and ideas to help this recovering Saab addict get this E39a figured out.
    Attached Files Attached Files

  2. #2
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    My lsj use to do that during dfco and I didnt like it but it was do to the spark advance during dfco was too low ... like 5 degrees advance so I upped it to 10 and it went away so maybe try lowering the spark to around 5 degrees during dfco and see how it fairs ... I'm also running practically open exhaust so it was much more noticable for me

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    Thanks! I'll take a look at that. Mine is still fully catted with only the final muffler deleted, throttle lift results in a smooth rev down.

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    Cant wait for the explanations, need to get the knowledge flowing for the LTG. Also your methodology on how you went about it would be extremely helpful.

    .Ill be tuning our 2016 Camaro in two weeks or so which has an injen intake, catted downpipe and mishimoto intercooler. I've been going over the tables for a week or so now and doing some logging and it looks relatively straight forward to get a safe tune started. Your tune looks like its not so straight forward but is netting some awesome gains!!...again thanks for sharing.

  5. #5
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    Forgot to mention you could probably also do it by lowering the spark advance in the lower rpm range/higher load areas to get it during accel instead of decel

  6. #6
    Senior Tuner cobaltssoverbooster's Avatar
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    retard the exhaust cam in decel zone was another technique back when i tried to make the lnf battle the srt4 backfires.
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    Hey everyone - Thanks for the notes! I'm running into a wall. The e29a ECU just doesn't have many DFCO settings, they all only apply to whether or not it comes on or not. I made an adjustment to simply not have it come on, but then I ended up with a lot of rev float; which would happen randomly, but the revs would sit at 3000rpm or higher until I used the clutch and wheel speed to force it down.

    I officially admit I'm too afraid to mess the the VE tables that you find in the Edit menu, and there seems to be no one talking about these yet. Any videos show much more direct routes to be sure you have a little extra fuel to burn with the crackling. Those all seem to be based on a different ideology than what GM (or Bosch) is doing with these ECUs. Trying to isolate the decel zones in maps is troubling as well, I'm going to need to get out there with the scanner to figure out where the timing and cams are at when decelerating.

    I have retarded the timing in the lowest two ranges of the main advance table between 1000 and 5600rpm, and that has resulted in some light crackling when revving and decelerating. So it's a start.

    @Deply - I'm going to get together an explanation in the coming weeks. Thanks!
    Currently: 2013 Cadillac ATS 2.0T Performance, 2001 Porsche 911 Carrera, 1999 Land Rover Discovery II, 1987 BMW 325i

  8. #8
    Tuner in Training Antonats's Avatar
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    Quote Originally Posted by egoexercised View Post
    Hey everyone - Thanks for the notes! I'm running into a wall. The e29a ECU just doesn't have many DFCO settings, they all only apply to whether or not it comes on or not. I made an adjustment to simply not have it come on, but then I ended up with a lot of rev float; which would happen randomly, but the revs would sit at 3000rpm or higher until I used the clutch and wheel speed to force it down.

    I officially admit I'm too afraid to mess the the VE tables that you find in the Edit menu, and there seems to be no one talking about these yet. Any videos show much more direct routes to be sure you have a little extra fuel to burn with the crackling. Those all seem to be based on a different ideology than what GM (or Bosch) is doing with these ECUs. Trying to isolate the decel zones in maps is troubling as well, I'm going to need to get out there with the scanner to figure out where the timing and cams are at when decelerating.

    I have retarded the timing in the lowest two ranges of the main advance table between 1000 and 5600rpm, and that has resulted in some light crackling when revving and decelerating. So it's a start.

    @Deply - I'm going to get together an explanation in the coming weeks. Thanks!
    Any updates???

  9. #9
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    Hey I'd like to try out your tune but you're running a manual transmission. Mine is Automatic.
    I'll send you my Stock tune. Can you add your tune without changing transmission parameters. Unless you feel they are beneficial.
    I'm currently running a modded tune but don't want to touch it.
    Attached Files Attached Files

  10. #10
    Advanced Tuner lt1z350's Avatar
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    just have to command -20 to -30 degrees when you lift no need to mess with dfco or anything else. Now sometimes making it command that low is tricky but I have done this on quite a few now with success and never touch dfco on any of them.
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    Tuner in Training Antonats's Avatar
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    Quote Originally Posted by lt1z350 View Post
    just have to command -20 to -30 degrees when you lift no need to mess with dfco or anything else. Now sometimes making it command that low is tricky but I have done this on quite a few now with success and never touch dfco on any of them.
    Yep figured this out finally!!! i'm getting some nice pops and crackle. I'm currently commanding -15 degrees on decel from 6000-4000rpm. Sounds amazing. Fair warning -24 to - 30 may have your neighbors call the cops on you LOL. Finding the tables were not as straight forward as I thought but ended up finding them.

    Thanks LTZ350
    Last edited by Antonats; 06-02-2019 at 12:53 PM.

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  13. #13
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    Quote Originally Posted by Antonats View Post
    Most excellent mod! I too struggle to find decel spark table. If you could help point a direction, would be most grateful!!

  14. #14
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    Quote Originally Posted by Emily89 View Post
    Most excellent mod! I too struggle to find decel spark table. If you could help point a direction, would be most grateful!!
    Minimum spark table. And a few cells in my main spark table. When you log watch the commanded spark when you let off the throttle after a wot pull. That's how I ended up finding where to tweak. I'm sure there is a better way to do it, and I'm no tuner by far. But logging daily on my 30 minute drive to work has taught me so much with this car. I'm glad I ended up keeping it vs trading it off for a money pit (BMW) lol

  15. #15
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    Can I ask how you disabled torque shaping on the ltg?