TunerPro User Forum

hi forum im searching to disable lambda for my m50b25 non vanos engine 402 ecu , xdf in download section doesnt have maps or something
can someone help plz ?

Hi bro
I have the same need of disabling lambda on 402 dme
I can’t change any idle and POT values online - have a feeling that lambda overrides my input

I found something on page 5 about lambda
We should put 0 to four or five lambda addresses, then ECU will ignore lambda and refer to fuel maps

UPDATE: I can find 2 HEX addresses and only, I can’t see other three in my bin, WTF?

Tried disabling all lambda adaptation tables using winols. Car turns off after a fraction of a second . Did anyone have this issue?

Hi found those lambda Maps for 402
7870 6*1
787e 6*1
788a 4*1
7894 4*1
789e 4*1 But lambda off isn't working.
Any suggestions ?

After trying for a long time I noticed that lambda adaptation can only change 5%in 402 so disabling it isn't that important

So its not 100% clear to my what i shoud do to disable lambda.
Anyone how can help me?
Also looking for disable MAF.

see That Hurxkens and adhamkhe have the same map locations and the data is completely different I think there is a version of BIN and version of XDF mismatch somewhere. Internal location markers in the ROM indicate the ROMs should start offset to x8000. I do not think any of the public 402 bins/xdfs are setup this way making it cumbersome to hunt around in the files.

In the 413/506/M3.3.1 cars the fastest way to turn lambda off is to unplug the lambda sensor. Same for the MAF, unplug it and the DME uses the fault map to run the car. I do not know if the 402/3.1 cars have the same fault map

To the lambda. The lambda maps where defined at 0x7870(no x8000 offset...but it should be) in the 7098 software version from some public sources. The 8599 software has different data there. Turning off lambda in software usually means setting the data of the tables to either 00 or FF for all the lambda tables. For the 7098 software these x7870 tables would all be set to 00/FF.

In 7949 and 8599 software I believe the structure has changed and my guess is this CF(6)RPM x D5(6)Load table Data at x77EA(or xF7EA with proper offset) This table is marked in the index of tables in the ROM. All those offsets only line up if the files are properly setup. Middle image 7949 soft is set to all 00 and is supposed to be a lambda off ROM. YMMV. This may be a RPMvLoad disable map. In 8599 there are the 2x 6x1 and 3x 4x1 maps at x7880(first data at x7886) These look like the same maps that got defined in the 7098 software but cannot be sure without testing.

The same/similar maps called lambda from soft 7098 are in a different location in 8599 software

thx voor the replay nomecone

i was not aware that there are different SW versions.
i have the OEM bin from my ecu, also a bin from a ''tuned'' ecu.
after copying the tune bin, iincreasing the redline and flashing this to a OEM 27c256, the car was running perfect and the redline was in fact increased using the XDF that i curently am using.

after checking the bin i can't find any similarity between your bin and myn regarding the lambda.
i will include my XDF, OEM and tuned bin.

my goal is to make most power out of a OEM M50B25 with 402 ( hobby in rallycross )
all tips and tricks are welcome

You should view with 16 bytes in a row. The data is there and it is same tables of data.
You should
1 offset the file so the index of tables table locations are correct.
2 used the index of table information to know where every table begins
3 If you do not already know, learn the Motronic axis label/descriptors and how the axis information works

Both of your files are 7098 software based. This information is at the end of the file. This is the data in your files. CF and D5 are axis label/descriptors.

Step 1:
Insert filler What the new offset looks like Now in app HxD you can highlight hex and jump to location of address. note some location are in big endian and some are in little endian. (forward and reverse reading of the bytes)

Step 2:
Image show some special bits that give you the locations of the start od the DATA calibration section. Here you will single values stored, next is the start of the DTC code settings area, next is the location of the DATA in table forms, Next is a index of the location of all the tables that have axis info included, then the end of the calibration data is marked

Step 2 continued

Here at FA44 this first a self address so you know you are in the right place. 44 FA -> FA 44 . Next is the location of each table written in little endian, last byte first.

So 44 F0 -> offset F044 - this is the location of the first table Step 3 begin...
Going to F044 you are at the first table
27 is the axis label/descriptor
0F is the number of axis points
followed by 15(0F) axis point numbers
followed by 15 data points
...
Then D3 at location F064 (which is in the index of tables) is the start of a new table. D3 is a descriptor. Hope this helps you get started.

I'm very new to 402 so have no clue how it works. ( will read-up about axis )
Thank you for the help nomecone!
I need some time to check this out and do some testing. ( will try this weekend )

I will probably come up with a lot of questions, how you will keep helping me with the 402 journey?
Thanks in advance

Hurxkens wrote: ↑Thu May 08, 2025 9:42 am I'm very new to 402 so have no clue how it works. ( will read-up about axis )
Thank you for the help nomecone!
I need some time to check this out and do some testing. ( will try this weekend )

I will probably come up with a lot of questions, how you will keep helping me with the 402 journey?
Thanks in advance

^ this helps some.

there is also
https://www.tunerpro.net/examples

I have not messed with 402s. I am using what I have learned from 413 and applying here. I have long term goals to cover all the Bosch e36 325-M3 DMEs of the era.

This is for 402 DME with 949 SW (O2 OFF)

bomj911 wrote: ↑Thu May 22, 2025 5:47 pm This is for 402 DME with 949 SW (O2 OFF)

That is awesome. Thanks. This could be put into a xdf as a patch to toggle it on the and off.