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Thread: Cadillac ATS - LTG Tuning - Exhaust Crackle

  1. #21
    Tuner in Training Antonats's Avatar
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    Quote Originally Posted by cobaltssoverbooster View Post
    by retarding the ignition advance to negative values you are specifically targeting the ignition late enough to burn some fuel in the exhaust port. this causes heat build up in the exhaust. repeated or constant heat abuse (particularly under load - ie: antilag) can cause turbine failure or cat damage.
    thats the long term effect.
    Thanks for the knowledge. I'll post later

  2. #22
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    Quote Originally Posted by cobaltssoverbooster View Post
    yeah its not that harmful. neons been doing it for years
    Thanks for info, did you have info how many is safe to retard ?
    so thoso little pops cant kill cat ?

  3. #23
    Senior Tuner cobaltssoverbooster's Avatar
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    oh the cat will eventually die from thermal cycling and if retarded far enough the pressure spike can do a number on the cat too.
    i ran my lnf with heavily modified cams and -15* ignition on decel because the exhaust gurgle was the trend when i had mine. i killed a hahn 3" exhaust cat in about a year and a half.
    it really depends on how hard you abuse it. to know though you would need an egt gauge mounted in the cat inlet to know what kind of thermal cycling the cat experiences.

    you guys are overthinking it i believe. i only stated the long term effects because it was somewhat brought up. if you want the sound then target it and run it.
    you may need to run decel slightly rich on purpose so if you have the ability to run in forced open loop (not a common lnf mode but possibly for your ltg depending on programming options) then it would be easier to make it more pronounced.
    run a decel fueling in the high 12 afr range and retard the ignition between -10 and -20 * to see what you get. play with ignition and decel enrichment until you get something that satisfies you. disable DEFCO and CFCO if you have control options for those systems.

    remember the cat is going to try and process raw fuel so the more you throw at it the shorter its life will be. the cat also muffles the effects a tad. my cams didnt really sound like they loped until i removed the exhaust and ran my 3" race pipe out the passenger side skirt behind the front wheel.
    Last edited by cobaltssoverbooster; 08-06-2019 at 08:07 PM.
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  4. #24
    Senior Tuner metroplex's Avatar
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    Did you just change the first 1 or 2 columns of the spark tables to -15 to set the ignition on decel?

  5. #25
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    Quote Originally Posted by metroplex View Post
    Did you just change the first 1 or 2 columns of the spark tables to -15 to set the ignition on decel?
    Yep, i changed 2 first Rows 8 & 12 airmass, from 2400 to 6000rpm. Main spark table and minimum spark table.

    Anybody know how to delay a dfco ?

  6. #26
    Senior Tuner metroplex's Avatar
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    I gave it a try on the LNF and it sounds awesome at first but after awhile it got boring. I'm all about power and MPGs now so shutting of DFCO wasn't doing it any good.

  7. #27
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    it doesnt disable DFCO, its just commands to spark a fuel late, if dfco was disabled the crackles be a lot more, you can also comfirm this with monitoring of instant consumption display.
    im searching how to late the DFCO entering state. to extend the crackles

  8. #28
    Can you share a crack / burble tune with me. Id love to try it out

  9. #29
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    You can copy spark tables from my tune, its BIG pops on pedal left after 2600 RPM, use at YOU OWN RISK, it will may damage you cats if there, and etc. im not responsible to any damage.
    do not do pops on low RPMs, i think 2500 its a minimum, i tuned to start pops on 2600 rpm, but after that there is a lot BIGer pops, lets me know how you fill with that.
    my Malibu are Without CATs, with only Magnaflow straight Muffler, sounds amazing.

    My-Malibu-15-stock-no-cat-hi-idle-pops-trans.hpt
    Last edited by kolyani4; 07-15-2022 at 10:51 AM.

  10. #30
    I'm trying to do pop on dece. but im having an issue with Torque MT advance.
    every time i let off the pedal i get lil pop but the torque MT advance is advancing the timing.
    How can i get rid of the Tq MT advance ?

    i retard the timing to -10 on High and low octane , MBT Torque timing , Minimum spark ( Base , Long term )

    ATS 2.5 LCV Engine with E39A ECU.

  11. #31
    Advanced Tuner lt1z350's Avatar
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    Quote Originally Posted by Mr.AT View Post
    I'm trying to do pop on dece. but im having an issue with Torque MT advance.
    every time i let off the pedal i get lil pop but the torque MT advance is advancing the timing.
    How can i get rid of the Tq MT advance ?

    i retard the timing to -10 on High and low octane , MBT Torque timing , Minimum spark ( Base , Long term )

    ATS 2.5 LCV Engine with E39A ECU.
    you will have to play with virtual torque then most likely. But dont mess with the mbt ever there is no need and that is going to cause calculation problems in yes torque management timing control so put that back first and try that. On the right path with the other settings. I do this alot on cars and some are easy others can be alittle more tricky.
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  12. #32
    Quote Originally Posted by lt1z350 View Post
    you will have to play with virtual torque then most likely. But dont mess with the mbt ever there is no need and that is going to cause calculation problems in yes torque management timing control so put that back first and try that. On the right path with the other settings. I do this alot on cars and some are easy others can be alittle more tricky.
    I tuned lot of cars for pop and never had issue like this. I think i need to try to play with virtual torque. i tried with out MBT table but i got the same issue.
    Shall i touch the first 2 rows only of virtual torque ?

  13. #33
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    Quote Originally Posted by Mr.AT View Post
    I tuned lot of cars for pop and never had issue like this. I think i need to try to play with virtual torque. i tried with out MBT table but i got the same issue.
    Shall i touch the first 2 rows only of virtual torque ?
    You tune 17 Camaro I4 turbo? I've got HP tuners on the way....My Camaro is FBO with a Spec stage 1 clutch and aluminum flywheel...Send me your info so we can talk business.

  14. #34
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    how do I get those pops and bangs that are loud? I dont completely understand so i need further explanation.

  15. #35
    Senior Tuner cobaltssoverbooster's Avatar
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    Quote Originally Posted by KovacsGeorge View Post
    how do I get those pops and bangs that are loud? I dont completely understand so i need further explanation.
    Pops and bangs during deceleration are a combination of overfueling and ignition retard. The fuel in the cylinder ignites really late due to lots of ignition retard and the slow burn generated from excessive fueling causes some of it to burn in the exhaust manifolds. A loud audible pulse is generated as a shockwave in the exhaust and you hear it as pops and bangs.
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