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Thread: My LLY DMAX Tuning Experiences (so far!)

  1. #1
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    Post My LLY DMAX Tuning Experiences (so far!)

    So I'll start off with what I have. A 2005 CCSB 4x4 LLY DMAX with an Allison that is now less than 500 miles from reaching 300k on the clock. I purchased the truck at 285k and had to do head gaskets immediately out of the gate (didn't know when I bought the truck, took me a week to do it!)

    Now I wanted to start getting involved with tuning, and I know for the diesel guys EFILive is where it's at, however doing some research there are some posts in here with valuable info I was able to learn to kind of make a tune for myself. The EFILive route would run me ~$800 whereas I'm $100 into the 2 credits and had the MPVI2 already when I was tuning my truck before this one (07 classic ECLB 2500HD 6.0/4L80e) so I figured it was worth a shot. Yes the EFILive offers the DSP5 switch for 5 tunes, but for the cost difference I figured if I make one tune that I'm happy with then there really is no need to get any crazier with tuning. I just want a mostly stock reliable truck that I can continue to use. Reading through this forum there isn't a ton of info but I was able to learn a tiny bit. Some of the files I wanted to check out date back to 2010/11 and they are not available to be downloaded through this forum anymore.

    So onto my tuning experience. I came across an extremely hot tune here that was a lot of fun and I copied a lot of the tables into my tune to kind of get a feel for it. My truck would fly with this tune and it would blow smoke like you would not believe but once turbo boost kicked in the truck ripped. The smoke was bad enough gunning it at 60mph would blow enough smoke to cloud up the entire 2 lane highway it was nuts. The torque was also awesome. I also have a goofy pedal at 600-1000rpm moving down the driveway where it would jump around a lot in rpms and be jittery, but this tune somehow managed to remove that entirely.

    Where I had issues with this tune however was mainly relating to fuel usage. It was extremely easy to put the truck into a fuel limp mode (where it detects below 29,000psi in the fuel rails) and would only allow you to rev up to 2000rpm until the code was cleared. In a day and a half of running this tune I saw the fuel limp code probably 10 times and a 5th gear slip once. It was enough for me to just axe this tune entirely. I did order a fuel rail pressure plug but honestly I don't think this would do a whole lot, to continue using this tune I 100% believe a lift pump is necessary.

    I did some more reading, and figured out I would try what is called the "20/20" tune which supposedly adds 50hp and found a thread on that here. I downloaded the 20/20 tune for a Topkick LLY from that page and looked over some more tables, and ended up using some info from both the hot tune and that 50/50 tune to make a decent overall one for my truck.

    I like this new tune, I had an issue where I would have an extremely rough jittery idle between 600-800rpm so I ended up using the stock LLY table information for the Main Injection and Main Injection Limits and this pretty much removed my entirely jittery idle and in normal driving circumstances this truck makes really good power and only emits a very small amount of black smoke when you gun it and is not anywhere near obnoxious like the first tune was. My jittery pedal going down the driveway is still slightly there, but I think I also need to look into the pedal spring too as I've been told.

    So if anyone is looking for reference, I've attached both the hot tune I used with my truck, stock tune, and the 20/20 tune I like and maybe this will help anyone researching in the future. I plan on working with the VGT a tiny bit to have a bit of an exhaust brake as well but for now this tune I am happy with and will continue to improve it with the more I learn and the more I mess with it.

    This is my first time messing with diesel tuning, but I am always looking to improve and share what I find out!

    2005 K2500 CCSB LLY 6.6-ALLI 20 20 tune updated 4-26-21.hpt
    2005 K2500 CCSB LLY 6.6-ALLI modded 4-25-21.hpt
    2005 K2500 CCSB LLY 6.6-ALLI STOCK TUNE.hpt
    Last edited by gstubbz; 04-28-2021 at 11:47 PM.
    2005 Chevy Silverado 2500HD CCSB LLY-DMAX/ALLI 300K
    HP Tuned, 4" SP, LBZ Intake, Fuel Rail Plug, otherwise stock



    1991 Chevy K1500 ECSB 4.3/5LM60
    6.0 LQ4 swap planned

  2. #2
    Tuner in Training
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    Glad to see someone out there tuning a diesel with HPT, i was in the same boat as you looking at the competitor vs HPT that i already had for my LS. Not much support but its quite fun and few of these guys will chime in from time to time. I am a novice at best but understand the basics. What EGT's were you seeing on that hot tune? I did the 20/20 started with my stock settings of course. works pretty good and shouldn't have any EGT issues even towing a bit (light car trailer and camper and sled trailer). I am surprised that your tranny didnt limp sooner if that tune was that hot. Welcome to diesel tuning!
    2006 GTO 403ci lsa heads kooks long tubes corsa ss exhaust OTR intake HPTuned

    2010 GMC Sierra LMM Duramax. Exhaust and tuned

  3. #3
    Advanced Tuner TheMechanic's Avatar
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    Thank you. Very little tunes here on the Dmax's. You da' man.

  4. #4
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    Thank you guys! Glad to see some other people reply in this sub-group since I know it's not really anywhere near as popular as the LS tuning goes.

    2 day update on the 20/20 tune. I really do like it, haven't managed to put the truck into any limp mode and it was nice to break the 98mph speed limiter and finally achieve 105mph on one of my pulls (prior 07 2500hd truck would do 120mph no problem, of course on my most recent trip down to Mexico) but I do think in terms of speed the gasser with a 4L80e was a much faster truck at high speeds and was able to take it, the duramax just kind of hates the high speeds where the gas truck had no issues. That 07 even had 4.10s where this dmax has 3.73s and come to find out the Allison transmissions have a lower ratio for OD (0.711 alli, 0.75 4l80e).

    The tune is good, but at idle it sounds like it has a loopy cam and I don't like it at all, so when I have some time to mess with it I want to work on ironing that out. Any other RPM range outside of 600-800 is fine. As of right now that is still my only downfall with this tune.

    For truck mod stuff, I just received my bigger flow turbo intake tube, fuel rail pressure plug, and also I have a fuel pressure regulator to help my little bit of a surge I had at idle that was pretty noticeable with the stock tune, and who knows once I swap that out maybe that will fix my complaint with the loopy idle. I also ordered a new pedal spring as well so who knows maybe all of those things together will help the truck out that much more but I'll post my discoveries.

    I actually don't have gauges on this truck for anything like boost, egt, fuel pressure, etc but I plan on adding some soon. I am planning on picking up a 30ft tandem axle gooseneck trailer within the next few weeks (it's been in the works now for like a month, waiting on the guy to get his new trailer before I can go get this one) so I know watching the EGTs will be a big thing on my radar as well.
    2005 Chevy Silverado 2500HD CCSB LLY-DMAX/ALLI 300K
    HP Tuned, 4" SP, LBZ Intake, Fuel Rail Plug, otherwise stock



    1991 Chevy K1500 ECSB 4.3/5LM60
    6.0 LQ4 swap planned

  5. #5
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    Another thing I will try doing this weekend, is a friend has a 05 LLY ZF6 truck that already has EFILive on it, so when it's up in my shop so we can do some interior stuff I plan on pulling his tune file from #4 (Optimized Stock, 80HP) on his DSP5 switch and hopefully that will give me some good numbers and I'll try implementing them with my tune. That might help out quite a bit! I'd like to pull the #2/3 (towing) tunes as well but I'm unsure if the DSP5 enables something else in the ECM and I won't be able to see modified tables when I pull the tune with HPTuners so we will see!
    Last edited by gstubbz; 04-28-2021 at 11:52 PM.
    2005 Chevy Silverado 2500HD CCSB LLY-DMAX/ALLI 300K
    HP Tuned, 4" SP, LBZ Intake, Fuel Rail Plug, otherwise stock



    1991 Chevy K1500 ECSB 4.3/5LM60
    6.0 LQ4 swap planned

  6. #6
    Tuner in Training
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    Yup i have a simple CS2 that i can do what i need (got it cheap since the guy thought it had tunes, and realized it was just a monitor). CTS3 though would be quite an upgrade but right now its not super needed.

    Let us know how you make out with pulling the EFI but i think that flashes a different OS that HPT cannot read. Plus many purchased tunes lock their tunes (much proprietary info in this diesel game)
    2006 GTO 403ci lsa heads kooks long tubes corsa ss exhaust OTR intake HPTuned

    2010 GMC Sierra LMM Duramax. Exhaust and tuned

  7. #7
    Senior Tuner Jim P's Avatar
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    EFILive uses a completely different section of the calibrations for the DSP/CSP switch tuning. If the ECM isn?t locked and you can pull a read, you won?t see a bunch of the changes done for the switch position.

  8. #8
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    i can not really figure out the timing calulator. base timing where do I find the point, there are 3 or 4 points below timing

  9. #9
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    Anybody have an experience with 2015 LML tuning? Im new tothis and trying to do a mild tune and delete on my 2015 3500HD4x4. I have a 40HP tune off my 09 LMM 3500HD 2WD Im judging off of but it didnt have DEF on it and Im a little leery of deleting the wrong thing....Help?