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Converting your E85 from the MS45.0 ECU to MS43

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vbelsky
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Converting your E85 from the MS45.0 ECU to MS43

Post by vbelsky » Wed Jan 02, 2019 12:48 am

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
32 23 Main Relay

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

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dj_jormi
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Converting your E85 from the MS45.0 ECU to MS43

Post by dj_jormi » Sun May 02, 2021 6:46 pm

vbelsky wrote: Wed Jan 02, 2019 12:48 am 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
32 23 Main Relay

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
Hello guy!

Finally, In the end, how did you do? Time passed and you did not update the post

Thanks :) :)

Z4lucas
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Joined: Wed Dec 13, 2023 7:05 pm

Converting your E85 from the MS45.0 ECU to MS43

Post by Z4lucas » Wed Dec 13, 2023 8:29 pm

Update?

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