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Thread: Why no DSP for LML?

  1. #1
    Forum tyhee Site Admin GMPX's Avatar
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    Default Why no DSP for LML?

    As most people in the Diesel tuning industry know, EFILive offers on the fly switchable tuning for many different ECM types from 2001 to current models, but the one we get asked a lot about is the E86A and E86B LML ECM, so I've decided to make this a sticky thread so anyone can find the truth behind it and why we can't offer DSP5 for these ECM's.

    For any switchable tuning to work EFILive needs to modify the original Operating code of the ECM to perform the switching functionality, on the E86A & E86B (aka Bosch EDC17) the operating system code is protected with a Digital Signature. The correct digital signature for the OS data can only be generated by Bosch as they hold the private keys.

    Although the OS data in the ECM is not encrypted (yet) the contents are signed to produce a unique 'digest' that is validated when the ECM is flashed via the OBD-II port.
    Like the image below shows, the 'Input' is some text, the 'Hash function' alters the text to create a unique 'Digest'.

    Picture from : https://en.wikipedia.org/wiki/Public-key_cryptography


    When flashing the ECM after the OS section(s) have completed the ECM will verify the data written generates the correct Digest that Bosch would have created for that section of code. And that right there is where we hit a wall, we cannot generate the correct numbers so the ECM will accept the modified data as valid, instead it knows the data is modified and will not complete the flash process.
    If you look at the image above you can see that it is impossible to take the data in the pink boxes and generate the text in Blue when we have no idea how Bosch created the Hash function (I believe they use a 1024 bit Key), but that is what we would need to be able to do for the ECM to accept any modifications to the OS code.

    Sadly there is no way to switch off this security check using any tricks via the OBD-II port, but this is the only reason we've never pursued DSP5 for the LML engine. Sometimes you just can't beat technology and for what it is worth there is no way to brute force figure the digests out either.

    Cheers,
    Ross
    Last edited by GMPX; October 12th, 2016 at 10:27 PM.
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
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  2. #2
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    I know you guys do not obsess over the competition, but how do you think EZ Link is doing it? Is there anyway we can change run modes via switch, kinda a built in DSP?

    Thanks

    Sam

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    I would be more interested in more tables in the current software then focus on DSP
    04 LB7
    2010 LMM
    2015 LML

  4. #4
    Forum tyhee Site Admin GMPX's Avatar
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    Quote Originally Posted by 30 RUM View Post
    I know you guys do not obsess over the competition, but how do you think EZ Link is doing it? Is there anyway we can change run modes via switch, kinda a built in DSP?
    I don't know exactly but I was told it is trickery to make it run in some different modes the ECM already has in there. Definitely not modified OS code like the traditional DSP & CSP OS's are. Ben has done a good job on figuring that all out.

    Quote Originally Posted by rcr1978 View Post
    I would be more interested in more tables in the current software then focus on DSP
    Says every user for every controller
    We have no "immediate" plans to add tables to the LML, new Duramax ECM is about to drop and we have been working on some new controllers for a while now. Hopefully they will be released early next year (no, not going to say what they are).
    Need official EFILive help, please go here.
    For tuning support please post your questions on this forum (or other auto forums).
    Sorry if I don't respond to your PM, don't take it personal.


  5. #5
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    Yeah I know there is lots of new ECM's hitting the market and the name of the game is to keep all us guys with support of the new stuff coming out. Was not to long ago my hopes of tuning a LML was very slim, then you guys came through after saying no way, keep up the good work you guys are awesome !
    04 LB7
    2010 LMM
    2015 LML

  6. #6
    Lifetime Member Road's Avatar
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    Quote Originally Posted by 30 RUM View Post
    I know you guys do not obsess over the competition, but how do you think EZ Link is doing it? Is there anyway we can change run modes via switch, kinda a built in DSP?

    Thanks

    Sam
    Limit the fuel quantity by varying the resistance of a sensor.

  7. #7
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    I looked into something similiar and it's really not worth doing. It won't change how the truck behaves at all, you'll just get well... A lower fuel ceiling.

    Messing with the barometer would allow you to do fancier things, but then you can't adapt boost for altitude. If you care that is.

    It other words, it's really nothing efi live can't do already.
    Last edited by Snipesy; November 18th, 2016 at 07:21 AM.

  8. #8
    Lifetime Member DURAtotheMAX's Avatar
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    Quote Originally Posted by Snipesy View Post
    I looked into something similiar and it's really not worth doing. It won't change how the truck behaves at all, you'll just get well... A lower fuel ceiling.

    Messing with the barometer would allow you to do fancier things, but then you can't adapt boost for altitude. If you care that is. The way I and I guess Ben was going for was to instead have it recieve the signal over CAN. I guess he got it to work, certainly never told me.

    It other words, it's really nothing efi live can't do already.
    PM'd you.
    2005 Silverado, CC/SB, 4x4, LT, LILLY/Allison
    12.9s @ 108 mph

    many thanks to Ross and Paul

  9. #9
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    I would venture that is what's happening. I did notice they are pining the switch to the ecm. I haven't got my hands on one yet though.

  10. #10
    Lifetime Member GMC-2002-Dmax's Avatar
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    About 10 years ago ROSS wrote an LB7 os with VFO, variable fueling option, it worked pretty good at the time and used a Rheostat.

    Anyway, BEN had a cool deal first, but it never made it to market.

    As the saying goes, you snooze, you lose !!!

    If there is demand, someone will fill it, some way, somehow.

    I am ordering a bunch of units, it's not going away, it's only going to grow, so you either beat them or join them........and that is just how it is.

    I'll be testing on my LML soon enough.
    www.ridgerunnerdieselperformance.com

    tony@ridgerunnerdieselperformance.com

    Tuner of many, many Duramax and Cummins Diesels.


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