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Thread: About to try some LLY tuning.. (Intoducing myself)

  1. #1
    Tuner in Training
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    Dec 2018
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    About to try some LLY tuning.. (Intoducing myself)

    Hello everyone,

    I've been lurking on here for a while, trying to figure out what resources exist for general diesel tuning knowledge, and other information specific to LLY tuning. Other than the sticky about flashing issue with LLYs, it seems like there isn't a whole lot going on, and what is here is generally quite old. I guess maybe it's because most of the Duramax tuning is happening via the main competitor's interface/software, like the tune that is currently on my truck from when I bought it.

    At any rate, I do a lot of gasoline engine tuning, usually using TunerStudio on MS3X setups I build, and I'm very open to doing some gasoline engine tuning using HP Tuners. So I thought it made sense in terms of overall flexibility to take a crack at the diesel side of things using an MPVI2. I was hoping that possibly the MPVI2 has some improvements that reduce or eliminate some of the LLY flashing difficulties, but truthfully I have no reason to believe that other than baseless hope. Lol

    In case anyone has guidance for me, my objectives for my LLY are simply to improve the efficiency in daily driving around areas, including freeway driving. I.e., attempt to gain some MPGs... Also, since diesel tuning is so different from gasoline tuning (almost completely opposite in some ways it seems), I just want to learn.

    Initially I want to log, so that I can see what rail pressure, pulsewidth, turbine vane position, injection timing, and injection pulse types are doing in the areas I would like to tweak. I did read there were some issues with even logging Duramaxes, so we shall see how that goes.

    Assuming it goes well, my initial thoughts are to see if there are efficiency gains to be made by trying to get the fuel in the chamber in a more timely fashion, giving up some smoothness characteristics, and possibly adding a few oxides of nitrogen or whatever. Seems like possibly reducing pilot injections and after injections, and then advancing the remaining fuel injections a little might be going in the right direction. Then maybe working the turbine vanes a bit in some areas to make sure the boost is in there where it needs to be to keep the mixtures leanish.

    Any of that sound correct?

    Thanks in advance!

  2. #2
    Tuner in Training
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    Dec 2018
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    So far so good! I was able to download the tune from my ECM, and compare it to a stock tune from the repository. Also, I was able to scan and datalog a drive, and successfully datalog via the bluetooth functionality of the MPVI2. It's FANTASTIC!

    The one thing I had trouble with so far was reading the tune from my TCM. Maybe it has something to do with the fuses needing to be pulled ala the LLY difficulties thread in the sticky, but at the moment I don't even care about it so I'll leave it for later. If anyone has any other guidance though, I'm interested to know.

  3. #3
    Potential Tuner
    Join Date
    Mar 2017
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    I've also been lurking a while. Diesel is somewhat foreign to me. I've tuned mostly BMWs (TunerPro) and LS motors (HPTuners).

    I recently acquired an 05 Sierra 2500HD with a ZF6. The previous owner installed an EGR delete, but didn't tune it out. So, it throws codes.

    I jumped on that with HPTuners because I already had it. Also fixed the speedo for the offroad tires it came with. Basically, just cleaned it up. It seems fine now, but for some reason the scanner on my laptop is not loading, so I'm not comfortable trying to tune it just yet.

    It came with a Banks Six Gun, which seems to work other than smoking a bit (prob bad glow plugs). Other than that and the EGR it's more or less stock. Although, it has a twin disc clutch. 😮

    Other 20/20 stuff I don't really have any Diesel related knowledge and am just trying to get a plan hammered out before I start messing with things I shouldn't, lots of searching I guess...

  4. #4
    Tuner in Training
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    Dec 2018
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    Thanks for posting! There seems not to be a lot of actual diesel tuning content on this forum about the actual diesel tuning process (or anywhere else for that matter, except for some stuff on YouTube about using WinOLS to tune VWs). Because of that, I actually bought the HP Academy "Fundamentals of Diesel Tuning" course. I have to say it helped a lot, even though it could definitely go deeper.

    With that said, I have successfully used the MPVI2 to retune my truck back towards stock in some of the low-load areas where the previous tuner did some things with pilot pulse fueling values and both pulsewidths (main and pilot), that don't make much sense to me. The truck is running much more nicely now, seems to be getting slightly more MPGs over the short distance I've driven it with the newest tune in it, and still has the same top end power. I didn't diminish anything in the high load areas of the tune, so that makes sense.

    I did find a guy about an hour and a half from me who has a loading style dyno, and reasonable hourly dyno time rates. After I figure out my plan of attack a little better, I want to head over there and do some steady state efficiency tests mainly related to main and pilot injection timing, and see if I can gain any more MPGs.

    Diesel tuning is some crazy stuff for a gasoline engine tuner like me, but it's very interesting, and fun. I have to say I am being drawn in to the diesel fold pretty rapidly.

  5. #5
    Tuner in Training
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    Oh, I also see I didn't post in this thread about the status of reading the TCM. Using Ver. 4.2.1, I struck out using the default "high speed" read option, even with all of the fuses pulled that are mentioned in the stickied thread about LLY read and flash problems.

    When I unchecked the "high speed" box, the TCM tune read out fine, albeit super slowly. Took about 14 minutes IIRC? And this was with all of the fuses still pulled. My guess is that the TCM might read out in slow mode with the fuses all in place with 4.2.1, but so far I haven't tried it.