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Thread: Converting your E85 from the MS45.0 ECU to MS43

  1. #1
    Join Date
    Mar 2014
    Location
    FL
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    My Cars
    Turbo '03 Z4 3.0i 6MT

    Converting your E85 from the MS45.0 ECU to MS43

    If you don't know what MS43 is:
    https://www.ms4x.net/index.php?title=Siemens_MS43
    It's the ECU that came in M54-powered E39 5-series, E53 X5s, Z3s, and most M54 E46 3-series models. Some E46 models had the MS45.1 ECU.
    Converting your Z4 to this ECU will make it much easier to tune the car for performance applications.


    My write-up on converting the E46 from MS45.1 to MS43 is an applicable reference:
    https://forum.e46fanatics.com/showthread.php?t=1113404
    MS45.0 uses the same narrowband oxygen sensors as MS43, so you will not need to replace your oxygen sensors with a different model.


    Aside from replacing your engine harness, MAF sensor, and adding the MS43 intake air temperature sensor, you will need to repin your transmission/O2 sensor harness:


    Pins:
    MS45 (old) MS43(new)
    1 1 Activation: Pre-Cat O2 #1
    2 13 Activation: Pre-Cat O2 #2
    6 7 Activation: Post-Cat O2 #1
    7 20 Ground: Pre-Cat O2 #1
    8 24 Ground: Post-Cat O2 #2
    9 21 Ground: Pre-Cat O2 #2
    10 22 Ground: Post-Cat O2 #1
    12 19 Activation: Post-Cat O2 #2
    14 18 Signal: Post-Cat O2 #2
    16 16 Signal: Post-Cat O2 #1
    20 14 Signal: Pre-Cat O2 #1
    22 15 Signal: Pre-Cat O2 #2
    23 Main Relay (same on both; leave as is)


    You will also need to add pins for your AC compressor trigger and coolant outlet temperature sensor, as those are part of the body harness on MS43 and MS45.1 cars, but part of the engine harness on the Z4.*


    *Information will be added in the future
    Last edited by VladBelsky; 05-30-2020 at 03:18 PM.

  2. #2
    Join Date
    Jan 2016
    Location
    Ca
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    6,981
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    2001 525it
    Geez it seems like a lot of work. What are the expected gains in performance do you think you will get.

  3. #3
    Join Date
    Jul 2007
    Location
    Philadelphia, PA
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    5,660
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    2005 M3 & 2004 330i
    You'll lose your alternator signal and oil pressure switch signals if you do this. That's transmitted via CAN-bus on MS45 cars, but MS43 doesn't transmit that by CAN. E85 cluster doesn't have pins to get that information by the physical switches.

    MS45 is just as tunable, it just hasn't been studied as much. Main complication was that it's RSA secured, but the key is 512-bit, which is easily factorable on modern computers (and has in fact been done).

  4. #4
    Join Date
    Oct 2006
    Location
    Oxnard, CA
    Posts
    498
    My Cars
    VF Z4, G-Power/ESS Z4Ms
    Quote Originally Posted by TerraPhantm View Post
    Main complication was that it's RSA secured, but the key is 512-bit, which is easily factorable on modern computers (and has in fact been done).
    Do you mean for reading/writing? Plenty of professional tools can do this with checksum corrections (KessV2 for example), and decent definition files have become available in the past year.

    The main issue IMHO is the MAF maxes out with only mild boost, and most “tuners” aren’t capable of performing a MAF rescale in conjunction with accurate injector scaling (modifier tables in the MS45.0). The stock engine can’t handle much boost anyway before head studs are required, and many shops screw up MLS head gasket installs by not performing adequate prep.

    I’ll be working on a tune for an aftermarket MAF sensor on my VF-based kit once I complete a couple other projects waiting in the queue... likely by late winter / early spring.
    VF Engineering Z4 3.0i | ESS VT2-500 Z4M | G-Power SK I Z4M | 996tt

  5. #5
    Join Date
    Jul 2007
    Location
    Philadelphia, PA
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    5,660
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    2005 M3 & 2004 330i
    May interest some people here. I released my MS45 flashing application along with its source code. Automatically corrects checksums and signatures. Can do both program and parameter writes. Works with any INPA cable. Completely free.

    https://forum.e46fanatics.com/showthread.php?t=1248513

  6. #6
    Join Date
    Jul 2020
    Location
    Bartonsville PA
    Posts
    2
    My Cars
    2004 z4, 2016 x1
    terra, been reading your post. Im up in the poconos, from Philly. Hit me up id like to talk with you about my z4 project.

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