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5HP18 & MS41.2 Transmission Flashing

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  • 5HP18 & MS41.2 Transmission Flashing

    Howdy folks, new member here (though a long time reader of this forum),


    I recently got ahold of a USA Spec 99' M3 Convertible, Auto, with 141k. Despite the auto and the additional weight, I am absolutely loving the car.

    The transmission shifts great, and behaves exactly as I would expect it to...except for a rather jolty 2-3 shift. It seems that the oncoming (F) clutch is struggling to match engine speed to the next gear during the shift phase, so when the shift ends and the F clutch goes to full line pressure, there's a jolt. It's not flaring at the moment- but the above behavior is the precursor to shift flare unless these transmissions just have a 2-3 shift like this and somehow hold up to that.

    Anyway, one day It'll get a manual, but it's simply not in my time or budget to do that at the moment, so I am looking to modify the transmission and or DME tunes in order to prevent the above behavior from causing excessive wear to the F clutch and prematurely killing the transmission...plus I just prefer aggressive power cuts with quicker shifts.

    I see that there are many options for DIY DME tuning using romraider, a flasher, and the like- but my question is if the same exists for the EGS? If shift power reduction is mostly handled by tables in the DME, I may be able to get away with not touching the EGS tune, but ideally I would be able to increase the shift pressure and make the power cut more aggressive to extend the life of the transmission. Fairly straightforward task, provided the tools to do so are avaliable.

    Does anyone have any knowledge on:

    1. If it is possible to read and flash the EGS over OBDII or the Diagnostic Port, and if the definitions are avaliable for the EGS

    2. Where the shift power interruption is handled. (DME primarily or EGS).

    And finally out of sheer curiosity...the DME cant do complete or rotational fuel cut for shift power reduction...right? It's not the end of the world if it can't because timing retard can be more than sufficient. Just curious though




    Cheers,
    Jon

  • #2
    are you experiencing the same issue whether you are in "E" and "S" mode?

    what do you mean by EGS?

    The transmission has its own module and a removable chip. The only aftermarket tune for that that I am aware of is Dinan which still sells it. All it does it raises the shift points of the car.

    Comment


    • #3
      Originally posted by bmwstephen View Post
      are you experiencing the same issue whether you are in "E" and "S" mode?

      what do you mean by EGS?

      The transmission has its own module and a removable chip. The only aftermarket tune for that that I am aware of is Dinan which still sells it. All it does it raises the shift points of the car.
      Hey!

      Unfortunately it happens in all modes, M E or S. And sorry for not being clear - I am referring to what most people call the transmission controller/TCM/TCU.


      ​​​​​I've seen a few of the Dinan options, much like there are replaceable eeprom chips for the DME as well (to tune without needing the flashing equipment). I'm hoping there's a way to flash the transmission controller as well - and that there are definition files available so I can actually make changes.
      Last edited by Jonohhh; 06-28-2022, 08:48 PM.

      Comment


      • #4
        The DME is a flash only option when BMW went with the MS4 platform for OBD II. The TCU for an automatic remained an eeprom chip regardless so really only left with Dinan.

        All things considered the ZF5HP is a pretty robust automatic transmission. There was a reason why they were used on the US m3s. I have seen some go over 200K miles without a problem. That said, are you sure yours is giving out? May want to start with a fluid and filter change and replace any leaky external seals (its common for the trans pan gasket and orings near the transcooler to start leaking at this age).

        If I recall you are in europe? the ZF5HP18 is pretty abundant as it was even utilized in the euro m50/m52 (325i and 328i) engines instead of the crappy GM ones the US standard 3 series used. So sourcing a low mileage good condition replacement should be more accessible for you.

        Comment


        • #5
          Your DME is flashable via cable, but you’re really over simplifying how easy it is. You can’t just make up your own tune unless you dedicate a lot of time into refining the fuel and timing tables. Not an easy task out on the street and the method of flashing adds significant delay in the process.

          There are a number of parameters you can easily tweak like rev limit and top speed delete.

          You will need a proper flashing software that corrects checksums. Quickflash is best for this: https://www.bimmertuningtools.com/fl...s41-quickflash Lastly, do not forget to use the 20-pin port to put the ECU into write access mode. The software won’t know whether or not you have done this so you can end up going through the whole flash process with no changes made. If you brick your ECU in your tweaking, you can reach out to me for a restore service. This is something that has to be sent in to repair.

          The transmission must have the chip removed and flashed on an eeprom bench flasher. The hardware to do it is cheap. The tune file to do so you likely will not find and you can’t just tune it yourself (no software with table definitions exist). You’re better off manual swapping.


          MSportParts | Braymond141

          Comment


          • #6
            Originally posted by bmwstephen View Post
            The DME is a flash only option when BMW went with the MS4 platform for OBD II. The TCU for an automatic remained an eeprom chip regardless so really only left with Dinan.

            All things considered the ZF5HP is a pretty robust automatic transmission. There was a reason why they were used on the US m3s. I have seen some go over 200K miles without a problem. That said, are you sure yours is giving out? May want to start with a fluid and filter change and replace any leaky external seals (its common for the trans pan gasket and orings near the transcooler to start leaking at this age).

            If I recall you are in europe? the ZF5HP18 is pretty abundant as it was even utilized in the euro m50/m52 (325i and 328i) engines instead of the crappy GM ones the US standard 3 series used. So sourcing a low mileage good condition replacement should be more accessible for you.


            Thanks much for the info- I did not realize the transmission controller remained eeprom only/non flashable throughout the whole run. I'm new to these cars - I'm used to e90s primarily.

            It's going to get a fluid and filter change in the near future. I'm not too hopeful that it'll do much since it behaves flawlessly apart from the 2-3, but we'll see!

            I'm glad to hear that they're solid transmissions... I'm hoping mine ends up holding on for just another year or so until I have an opportunity to manual swap it. For its time though, the shift logic is pretty impressive when in S mode- much less intrusive than most all automatic transmissions from its time. And unfortunately I'm from the US where I believe they are less plentiful - though they're available nonetheless. I guess I'll need to decide if I want to go that route or go for a gs6-37bz or 420g. Time will tell.


            Thanks, Jon

            Comment


            • #7
              Originally posted by Braymond141 View Post
              Your DME is flashable via cable, but you’re really over simplifying how easy it is. You can’t just make up your own tune unless you dedicate a lot of time into refining the fuel and timing tables. Not an easy task out on the street and the method of flashing adds significant delay in the process.

              There are a number of parameters you can easily tweak like rev limit and top speed delete.

              You will need a proper flashing software that corrects checksums. Quickflash is best for this: https://www.bimmertuningtools.com/fl...s41-quickflash Lastly, do not forget to use the 20-pin port to put the ECU into write access mode. The software won’t know whether or not you have done this so you can end up going through the whole flash process with no changes made. If you brick your ECU in your tweaking, you can reach out to me for a restore service. This is something that has to be sent in to repair.

              The transmission must have the chip removed and flashed on an eeprom bench flasher. The hardware to do it is cheap. The tune file to do so you likely will not find and you can’t just tune it yourself (no software with table definitions exist). You’re better off manual swapping.
              Hey, thanks for the input,

              Regarding tuning- I was hoping to read/extract the current tune from the DME as to not need to mess with the actual engine calibration - and just look out for any transmission torque reduction related tables and modify those. I figure it's mostly handled in the auto trans controller, but surely there is some translation in the DME for power reduction request vs ignition timing retard or something of the like. It's all speculation until I can pull the .bin, however.

              But regardless, the hardware and software needed to flash is stuff I planned to acquire anyway since once it does eventually get a manual, I will most definitely be tuning it (I have quite a bit of experience doing engine calibration...but am pretty clueless about this platform). I'm glad to hear I can send it out to you if I brick it.... hopefully I don't have to but.I am glad nonetheless.

              If there's no publicly available bins for the egs then I guess it's all moot even if it was flashable. It seems Dinan may be the only ones with them and I'm sure they're protected as IP.
              ​​​​​​

              Thanks again!

              Comment


              • #8
                Originally posted by Jonohhh View Post

                Hey, thanks for the input,

                Regarding tuning- I was hoping to read/extract the current tune from the DME as to not need to mess with the actual engine calibration - and just look out for any transmission torque reduction related tables and modify those. I figure it's mostly handled in the auto trans controller, but surely there is some translation in the DME for power reduction request vs ignition timing retard or something of the like. It's all speculation until I can pull the .bin, however.

                But regardless, the hardware and software needed to flash is stuff I planned to acquire anyway since once it does eventually get a manual, I will most definitely be tuning it (I have quite a bit of experience doing engine calibration...but am pretty clueless about this platform). I'm glad to hear I can send it out to you if I brick it.... hopefully I don't have to but.I am glad nonetheless.

                If there's no publicly available bins for the egs then I guess it's all moot even if it was flashable. It seems Dinan may be the only ones with them and I'm sure they're protected as IP.
                ​​​​​​

                Thanks again!
                You do bring up a good point though that there could be variations in both the ECU tune depending on your cars configuration.

                I can at least confirm that was the case with the S50 OBD I DME made by Bosch. Depending on the configuration (i.e. pre 12/94, manual or auto), Dinan had a few variation of their Stage 1 ECU tune.

                Comment


                • #9
                  Once I get my hands on a .bin I'll look through to see if there is anything relevant related to the tranmission that has been defined. I'm not too certain I'll find anything based on what others seem to be saying- but there's gotta be at least something in the DME regarding the power reduction strategy...I'd think anyway.

                  Just making the shift power cut stronger will extend the life of the transmission without a doubt, but without modifying the pressures or timings accordingly, there's not too much you can do before you start running into undesirable behavior during shifts due to the unlocked-during-shifts torque converter.

                  With full control to tune every parameter, it is most definitely possible to get the 5HP to absolutely bang through gears without reducing its life expectancy, provided you're okay with a harsh near full power cut. I personally prefer that anyway... but it's not for everyone. If you look at Porsche's implementation of the 5HP19 on the 996 Carerra 4s, it's actually pretty crisp.
                  Last edited by Jonohhh; 06-30-2022, 03:39 PM.

                  Comment


                  • #10
                    There are no ECU based performances changes you can make for the transmission.

                    Manual swap and use your feet to improve launch and shift characteristics.

                    MSportParts | Braymond141

                    Comment


                    • #11
                      Originally posted by Braymond141 View Post
                      There are no ECU based performances changes you can make for the transmission.

                      Manual swap and use your feet to improve launch and shift characteristics.


                      Yeahh, I'm pretty much certain at this point that there's no public definitions for the EGS software, so even if I did pull the eprom and read it, there's nothing meaningful I can really do with my skill set.


                      Ill put a manual in it one day, but my X1/9, 500 Abarth, 06 330i, and 65' Impala are all manuals so it's admittedly kind of nice to have an auto- was just hoping to extend its life and have some fun ( I love tuning planetary transmissions ) for a while until it gets swapped in a few years. Plus, I really wanted to hear the 5HP banging through gears.

                      It was worth a shot but I appreciate the help everyone!
                      Last edited by Jonohhh; 07-09-2022, 01:07 PM.

                      Comment

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