So I've done a manual swap and thrown on k04s onto my 091 Audi allroad, and I'm uncomfortable with tuning the ECU, however prepping it for my tuner I was trying to get the ABS coded correctly and I couldn't nail it down.  I have the original ECU untouched, but I have been using a 2000 A6 ECU as it was already a manual and didn't have an immobilizer, and I thought it would allow me to not have to flash the ECU because I didn't feel comfortable doing that.  I however through more research am thinking that I will have to flash the ECU in order for some coding to stick and work correctly together.

here's what I have done already:

correctly coded instruments cluster to not look for the auto trans.

coded the brakes to have the correct specifications for my car and the coding stuck(which I thought was a good sign) and I was able to do a steering angle calibration.

However I still had abs on my dash so I looked further.  The original ECU did not have ESP like the allroad has, and the ABS and the engine don't like not being on the same page.  I learned that the engine is coded for no ESP/ASR, and I needed to log in and fix that by changing the softcoding in the engine module from 06612 to 06712.

When I attempt to do that it will not take the coding, which I assume is due to it being an APB, and it will not allow me to recode the engine to the proper coding.  What is the consensus here, am I logging into the engine module wrong, and that is why I cannot correctly change the coding, or do I need to flash the ECU with a manual allroad file and restart the coding of the modules all over to see if the ABS and engine will like to play along? or are there other files that I need to flash like a late S4 that has ESP, or a later A6 with the same?  thanks for the help in advance, I hope my block of text is manageable for y'all to read.

The original allroad ECU is P/N 427 907 551 K

The donor A6 ECU is P/N 4B0 907 551 K

is there any other info you would need me to post?

Would I need to get a new ECU, or would I have the option to flash a new base file into the old A6 ECU with no immobilizer? I was under the impression that if I flashed a manual A6 file with abs it would come with the correct 06712 coding (or maybe 06711? Can't remember if the A6 and Allroad are a different end to that coding), then I could specify the other trivial ABS stuff.

I already got rid of air suspension, so I'm not worried about staying exclusive to Allroad files for the air, but more wanting it to work so that I feel better when the tuner looks at it lol.  Thanks for the help so far though.

I am assuming you cannot rewrite that field in this old of an ECU because as far as I know the manual swap needs a ECU flash in APB engine codes, I figured that this was the reason for that.

S4 M (6sp) or L (tip) would be your best bet.

See my sig.

Correct. M/L is has one the most extensive xdf (and a 5120 file) available.

If your car had immo, though, you will lose that functionality.

it loses immo when I use the A6 ECU regardless, I am not looking to keep that functionality anyways, just want it to run correct first and if I want security I can figure out all of that at a later time.

So does the flash allow me to alter the coding then? I guess I understood wrong as I thought the flash would have the correct coding for modules that I cannot usually edit.