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Discussion Starter #1 (Edited)
Hello e46fanatics,

our ECU, the Siemens MS43, is limited to read 1024kg/h of air. After applying the MAF hack, this value doubles to 2048kg/h and therefor enough flow for bigger MAFs.

A cheap alternative for the HPX PMAS MAF is manufactured by Bosch with the part number 0 280 218 067 (or 0 986 280 219) and is installed on the Audi (R)S4 B5's 2.7 V6 biturbo engine and is able to measure upto 1800kg/h.

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The MAF sensor module comes preinstalled in a 3.5 inch housing and has a 5 pin connector (Audi part number 1J0973775A) with the following pinout:

  • Pin 1 - IAT sensor output (not used)
  • Pin 2 - voltage input 12V (red?)
  • Pin 3 - common ground (black)
  • Pin 4 - voltage input 5V (brown/white)
  • Pin 5 - MAF sensor output (yellow)
The IAT output on pin 1 can be connected to an aftermarket logging device to monitor the intake air temperature before compression, or in case you leave it unconnected, make sure to seal the pin in the plug, to prevent the maf from corroding like this.

Pins 2, 3 and 5 should be self explaining, you can just connect them to the OEM MAF wires, or create a new 4-wire loom and run it to the cable distribution box located under the intake manifold.

Pin 4 need a solid 5.00 volts supplyvoltage, as this is the reference for the MAF output signal. This is absolutly crucial for the MAF to work properly!

The MS43 has two integrated 5V outputs, one for the electronic accelerator pedal and one for the electronic throttlebody, which you will preferly use, because you can tap into the wire right in the distribution box.

By the way, this is pin 7 at the middle ECU connector (X60003) for the voltage U_DKG according to the manual (brown/white, 0.5mm²)
If anybody is concerned about the MAF drawing too much current, during operation it only needs 1,1mA :thumbsup:


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Now that you have the connection from the MAF to the ECU, the next part is applying the MAF hack (512k file) and editing the sensor definition (64k file) :D

You have two options to double the MAF limit:

  • First is to do it manually with a HEX editor and changing the bytes 0x3D8A3 and 0x3D8C7 from "4E" (1024kg/h) to "3E" (2048kg/h) and double the conversion in the Tuner Pro MAF table to "0.03125*X"
  • Second is downloading RomRaider and the MS43 definition .XML file, flick the switch under the "Forced Induction" section and use the special MAF table right next to it.
Either way you have to recalculate the four checksums in the 512k file, even if you use the CHK5/EWS delete File from Daniel, as this only disables the fifth checksum in the 64k file.

In addition to that, you need to set "C_MAF_KGH_R_LS_MES_MAX" to 1800kg/h.

Today I discovered, that "C_ABC_INC_MAF_MON" and many other constants lay within checksum 4's area. This means you can only edit this value in the 512k full flash. (Look over here for details)

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The user jd_improved was kind enough to share his sensor definition and allowed me to publish it in form of an Excel, respectivly CSV, file, that you can download from my Google Drive over here. Just copy and paste the new values over the existing ones :thumbsup:

I will also provide an updated 512k file with the MAF hack for all M54 engines, correct checksums and the RS4 MAF characteristic already applied and the corresponding XDF file for editing it with Tuner Pro for the lazy people. :D


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Note 1: Credits belong to Daniel_F. for his amazing files, jd_improved and volter for the Bosch characteristic and the RomRaider team for the MAF axis values!

Note 2: The RS4 MAF measures backflow in the section below 1.00 volts and therefor it's zeroed out in the table, since the MS43 can't understand .

Note 3: The XDF file published by MS43info on the 16th Feb. contains an error in the MAF voltage axis, I corrected it with the correct values from the RomRaider axis.

Note 4: This is not the holy grail, so let me know if there is room for improvement. Malfunction can happen, but that's why this board exists, let's figure this out together!



Have a nice day :craig:
 

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Discussion Starter #2 (Edited)
Further information



  • 2048kg/h MAF hack bytes for the different software versions:
    • MS430037: 0x3D719 & 0x3D73D (verified by Daniel_F.)
    • MS430055: 0x413A3 & 0x413C7 (verified by Daniel_F.)
    • MS430056: 0x3D8A3 & 0x3D8C7 (verified by Daniel_F.)
    • MS430064: 0x3E0E5 & 0x3E109 (verified by Daniel_F.)
    • MS430066: 0x3B4C3 & 0x3B4E7 (verified by stefm5)
    • MS430069: 0x3B4C3 & 0x3B4E7 (verified by Daniel_F.)



  • Pictures of creating and installing the new MAF connection

    Creating the 2.5m long cable to get the MAF to the passenger side
 

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<double the conversion in the Tuner Pro MAF table to "0.03125*X">
can you explain this?
since i'm working on 0066 version i will try everything manually.
the switch on 66 is at 0x3B4C3, 0x3B4E7.

anyway congrats for the guide!

edit: you meant edit parameter XDF info
 

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Discussion Starter #4
I will add some deeper going information and pictures about it in the second post. Should be ready this evening!
 

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I will add some deeper going information and pictures about it in the second post. Should be ready this evening!
:bow::bow::bow:

i tried to copy my 66 tune to 56 version but there are about 7 or 8 tables undefined for both versions.
 

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Discussion Starter #6
Yeah, unfortunately there are, I discovered that when I was converting the Shark Injector tune from version 430066 to 430056...

I started a list for the MAF hack bytes, so feel free to contribute :)

Update for CHK4: Daniel send me a possible fix for that one :thumbsup:
 

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"C_ABC_INC_MAF" and "C_ABC_INC_MAF_MON", set "C_MAF_KGH_R_LS_MES_MAX" to 1800kg/h and C_MAF_MAX to 1389kg/h (the highest value possible for this constant).

Today I discovered, that "C_ABC_INC_MAF_MON" and many other constants lay within checksum 4's area. This means you can only edit this value in the 512k full flash.
i can edit "C_ABC_INC_MAF" and "C_ABC_INC_MAF_MON" in the 64k file but not in the full 512k file.
also i cannot edit maf maps in the 512k file. :hmm:
 

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In addition to that, you need to suppress the MAF DTCs with zeroing "C_ABC_INC_MAF" and "C_ABC_INC_MAF_MON"
That isn't necessary. It is very good to know when your air flow meter broke down (fail), especially in forced induction aplications.

Next thing for checking. Below 4.75Volts MAF curve you shared is very acurate (almost identical like mine), but is completely incorrect in 4.77-5V area. Map from RS4 can read 1800kg/h not 2048kg/h.
 

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Below 4.75Volts MAF curve you shared is very acurate (almost identical like mine), but is completely incorrect in 4.77-5V area. Map from RS4 can read 1800kg/h not 2048kg/h.
You are right, the maf is originally specified to 1300kg/h at 4,6 V but actually it measures up to 1800kg/h. In my application I don't need more air at the moment, so I interpolated it by hand.

If you have an accurate curve above 4,6V please share it with us.

By the way what are the 1389 mg/stroke in kg/h to which the ms43 is limited to work with?
 

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Discussion Starter #15
Thank you a lot volter, I updates the BINs and Excel files in the first post and re-enabled the DTCs.
 

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2048kg/h MAF hack bytes for the different software versions:
  • MS430037: 0x3D719 & 0x3D73D (verified by Daniel_F.)
  • MS430055: 0x413A3 & 0x413C7 (verified by Daniel_F.)
  • MS430056: 0x3D8A3 & 0x3D8C7 (verified by Daniel_F.)
  • MS430064: 0x3E0E5 & 0x3E109 (verified by Daniel_F.)
  • MS430066: 0x3B4C3 & 0x3B4E7 (verified by stefm5)
  • MS430069: 0x3B4C3 & 0x3B4E7 (verified by Daniel_F.)
Here´s an update of the position of the switch in different software version ;)
 

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@ volter thank you for the curve :thumbsup:





:facepalm: yes of course...
if i didn't understand your question feel free to explain.

you have two limits in ms43. 1389mg/stk and 1024kg/h.
the only thing one can calculate is in which rpms this scenario happens.
if you don't have maf limitation, then kg/h conversion depends on given rpms.
 

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Discussion Starter #20
And as engine load is proportional to airflow and rpm, and the 1024kg/h limit is doubled to 2048kg/h, this nearly never happenes afaik, or we need to exceed 7200rpm, which equals 1800kg/h.
 
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