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    MS43 injector scaling

    Dear fanatics,

    Long story short, I installed a custom setup on my M54B30 euro with MS43 dme. I actually 'tuned' myself and I can say I got good results till now.

    What I feel like challenge is the injector scaling. As far as I know, this dme has a global constant and 6 other individual constants for the injector size which is 128dec. To scale that to use 650cc (62lb) injectors the formula used gives constants rounded to 50. I changed that and I got a real bad idle with lots of smoke. Apparently the car was horribly rich, WB readings were in the 9-10 which eventually flooded the engine. I hate failing my thoughts and confidence but I am sure something out there I am missing. I am looking to stabilize the idle and start scaling the fuel maps from there. I forgot to mention I did some base tune for these maps for the light loads (idle maps) before starting the engine.

    Any help or thoughts would be much appreciated

    Excuse any spelling or English mistakes. Sometimes it is the auto correction and most of the times it is me Click here to enlarge

  2. #2
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    Referring you to @bluejeansonfire and @PEI330Ci

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    I would be happy to hear from them both. Bluejeans' build is awesome, and I consider PEI the god of M54Click here to enlarge
    I already referred to their various threads in my own build

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    Try talking to @NickG as well.

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    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    Dear fanatics,

    Long story short, I installed a custom setup on my M54B30 euro with MS43 dme. I actually 'tuned' myself and I can say I got good results till now.

    What I feel like challenge is the injector scaling. As far as I know, this dme has a global constant and 6 other individual constants for the injector size which is 128dec. To scale that to use 650cc (62lb) injectors the formula used gives constants rounded to 50. I changed that and I got a real bad idle with lots of smoke. Apparently the car was horribly rich, WB readings were in the 9-10 which eventually flooded the engine. I hate failing my thoughts and confidence but I am sure something out there I am missing. I am looking to stabilize the idle and start scaling the fuel maps from there. I forgot to mention I did some base tune for these maps for the light loads (idle maps) before starting the engine.

    Any help or thoughts would be much appreciated

    Excuse any spelling or English mistakes. Sometimes it is the auto correction and most of the times it is me Click here to enlarge
    First off, I've never tuned an MS43 DME....I leave that to the experts. But....I do understand a little bit about ECUs and tuning in general.

    One thing I suspect you are missing is the latency or dead time of the injector. You can change the fuel tables, but if the dead time is not accounted for, the actual fueling will be off.

    Secondly, the spray pattern of the "new" injector will affect fuelling a huge amount at idle and and at part throttle.

    What I'm saying is that need to start from scratch with your fuel map to do this right. There's no re-scaling of the fuel table that will account for the 2 factors I've mentioned above. In open loop fuelling, you'll be able to get close, but once the ECU switches to closed loop fuelling the AFRs will go nuts without the dead time and port wall wet-down (Tau) figured out.

    This is why when choosing a fuel injector, I usually recommend talking to whomever will be doing the tune. Usually they will have a preference which they have worked out most of the above before hand.

    For my silver car (330i), I'm admittedly starting from scratch and thus using a high-end stand alone ECU to run the car. (For many reasons)

    Nick G admittedly is a major source of my information. Hopefully I've got it right above from what he's written over the years, and the few engine management tuning books I've read.
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    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    I would be happy to hear from them both. Bluejeans' build is awesome, and I consider PEI the god of M54Click here to enlarge
    I already referred to their various threads in my own build
    Julio has done a great job!

    I'm certainly not "all-knowing" of the M54, but I do seem to collect a good information from many very knowledgable sources. I'm glad you appreciate their knowledge. Click here to enlarge
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    Glad to hear from u Adam. Man...what u did with ur black car was purely UR workClick here to enlarge I even documented ur 40 page thread in one huge word fileClick here to enlarge Especially what u sliced the engine Click here to enlarge hehehe I can clearly see your work here Click here to enlarge

    Anyway, I forgot to mention earlier I already have the dead time table location map adress along with its factors. Actually I just got the idea of testing them on the current stock injectors to make sure I am on the right track and sorted the code right. I however am not sure if adjusting the dead time table for the new 62lbs and sorting out the various fuel tables along (I have plenty of time testing daily after work on streets) would be ok or if That will need scaling the injectors as well.

    Anyway the car is now being modified from bottom to top mount as I had real hard times with the first setup. I will post about that once I get it back in couple of days.

    Again excuse any mistakes, I am just typing fast from my mobile

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    And actually my next step would be making a similar fuel rail like the one u made on the black car. Sourcing the raw Ala tube with the needed dimensions is not easy, although I have my own CNC machines (I am a mechanical engineer)

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    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    Glad to hear from u Adam. Man...what u did with ur black car was purely UR workClick here to enlarge I even documented ur 40 page thread in one huge word fileClick here to enlarge Especially what u sliced the engine Click here to enlarge hehehe I can clearly see your work here Click here to enlarge
    I would be interested in getting a copy of that, I don't have all of that stuff in one place....thought of doing that myself some time but just haven't had the time.

    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    Anyway, I forgot to mention earlier I already have the dead time table location map adress along with its factors. Actually I just got the idea of testing them on the current stock injectors to make sure I am on the right track and sorted the code right. I however am not sure if adjusting the dead time table for the new 62lbs and sorting out the various fuel tables along (I have plenty of time testing daily after work on streets) would be ok or if That will need scaling the injectors as well.
    There are lots of methods to work this out, but the best is to get the injectors bench tested.....then you'll have the true dynamic response.

    Most good tuning books, including a really good one from Greg Banish, go into detail with how to work on this.


    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    And actually my next step would be making a similar fuel rail like the one u made on the black car. Sourcing the raw Ala tube with the needed dimensions is not easy, although I have my own CNC machines (I am a mechanical engineer)
    CNC would be nice...I used a drill press as you know. The fuel rail stock you can get from lots of vendors...I think mine was a 3 ft piece from Edelbrock?
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    I have the file on my pc...will look for it tomorrow and send it to u. It is half edited as u know copying a web page and pasting to a word file gives some annoying spaces and stuff like that...also removed the replies.

    I don't think I can access a bench test here...I am in Egypt as u know and such "specialized" equipments are like rocket science to ppl hereClick here to enlarge

    I thought of measuring latency with MS but need to see a friend of mine who is willing to share his already installed one instead of getting one.

    In fact I know it will be much easier to go to a piggyback like AEM F/IC or a standalone like MS or halltech but at this time I will feel like failing myself...if u know what I meanClick here to enlarge that would be exactly like when someone asks u that silly question "y didn't u sell ur black 330 and get an M" Click here to enlarge

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    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    I have the file on my pc...will look for it tomorrow and send it to u. It is half edited as u know copying a web page and pasting to a word file gives some annoying spaces and stuff like that...also removed the replies.

    I don't think I can access a bench test here...I am in Egypt as u know and such "specialized" equipments are like rocket science to ppl hereClick here to enlarge

    I thought of measuring latency with MS but need to see a friend of mine who is willing to share his already installed one instead of getting one.

    In fact I know it will be much easier to go to a piggyback like AEM F/IC or a standalone like MS or halltech but at this time I will feel like failing myself...if u know what I meanClick here to enlarge that would be exactly like when someone asks u that silly question "y didn't u sell ur black 330 and get an M" Click here to enlarge
    I think you are going to be much happier in the long run figuring out how to tune the DME if you have the time and resources to do so.
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    That's indeed right


    I just hope I can get the scaling done right.

    If I can idle with the new injectors that will the next successful goal
    Any help will be appreciated

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    Click here to enlarge Originally Posted by CAI330i Click here to enlarge
    That's indeed right


    I just hope I can get the scaling done right.

    If I can idle with the new injectors that will the next successful goal
    Any help will be appreciated
    Well....this sounds pretty simple:

    - rescale the fuel table for the new injectors
    - find the injector offset value on the DME, and adjust to specs for new injector
    - find the battery compensation table for injector duty cycle, and adjust to specs for new injector

    That will be a good start....but then you will need to fine tune both the open loop fuel table, and the closed loop Lambda target value table.
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