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Thread: Used truck purchase with locked tune and dpf re-installed

  1. #1
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    Used truck purchase with locked tune and dpf re-installed

    Should I be concerned that I have a tuned 2009 LMM duramax with a locked tune and the DPF re-installed?

    The logic I seem to understand is that the computer won't regen and hence I could end up with a plugged DPF and a dead motor. See as I don't have the original tune I can't read and re-enable the DPF regen and codes for the computer. I live in an emission compliant area and running without the emission equipment will give me a failure.

  2. #2
    Tuning Addict 5FDP's Avatar
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    I'd be concerned because you want the truck to regen if the DPF installed.

    Seems that you might have to have a dealership flash a stock calibration into the computer again. Though it's maybe possible that because it's locked that no even their equipment will over-write it.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  3. #3
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    Well fortunately the only thing that has been changed was the DPF. The new shiny nuts and tune lockout gave the issue away. Half of the reason I have HP tuners is to check a used vehicle. The other half was to tune my S10 Blazer after I added a supercharger.

    The truck was a trade-in and so I have a couple of options from the dealer. The previous owner might be able tell me who the tuner was so I can have them unlock and re-program back to factory or I work with them somehow, or the dealer can re-program back to factory. I know that sometimes that the GM tech 2 can't re-program a locked ECU.

  4. #4
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    Perhaps I should state what I am experiencing. I get this message: Reader Upload Request: x7F Negative response code error. The message occurs every time.

    Also things are a little weird in the VCM scanner too. Not all of the channels will show data. Different channels will show data each time I plug into the truck. I have included two logs to show what is happening.

    Now my background and what I do professionally is an embedded firmware electrical engineer. Should I use a logic analyzer on the can bus? Should I dig into what is going on here? Maybe scope it?

    Perhaps I am experiencing the problem described here: https://forum.hptuners.com/showthrea...uirks&p=290527 ? I have an LMM duramax.
    Attached Files Attached Files
    Last edited by rapsure; 3 Weeks Ago at 12:45 PM.

  5. #5
    A GM TIS should overwrite it with no problem. Are you polling the channels and saving the layout so you don't have to do that every time ? along with removing all the appropriate fuses, make sure there are no aftermarket devices taped into any wires any where. Anything that can kick the bus off line.

  6. #6
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    Quote Originally Posted by staytuned View Post
    A GM TIS should overwrite it with no problem. Are you polling the channels and saving the layout so you don't have to do that every time ? along with removing all the appropriate fuses, make sure there are no aftermarket devices taped into any wires any where. Anything that can kick the bus off line.

    What is a GM TIS, what GM engines does it work on and how do you go about preforming one, I have never herd of it before and would like to know more about it and any other tricks you might know.

  7. #7
    Tuning Addict 5FDP's Avatar
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    GM TIS is GM's diagnostic and calibration service. You would need a scan tool that could put a GM calibration into the computer. You pay for the service.

    https://www.acdelco.com/for-professi...ogramming.html
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

  8. #8
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    I took care of the tune a few days ago. I took the truck to the dealer and had the computer programmed back to stock. I know it is boring, but now I can use hptuners and work with what is there. I still get the same behaviour with reading the different channels though as I posted above. I haven't seen any after market devices attached anywhere. Kinda boring for the moment. I did add a S&B intake now to lighten the wallet. I'm thinking a lift pump would be nice so I can have a water separator and I have a large 52 gallon fuel tank. Since I live in an area that stays below freezing for about 3 months I will likely get some condensation in the tank.

    I new to the tuning of a diesel so I'll need to some learning and research.

  9. #9
    There's a couple '08 LMM tunes in the repository with deletes. Follow their lead without deleting anything. Cut the EGR back to at least 50% everywhere, if it sets a code for that step it back up, if not cut it back more. That will help keep the intake ports cleaner and lengthen regen distance. It's hard to tell how much fuel you have cranked in because of the lack of black smoke, so be careful on fueling. Too much timing and you can hear it.