Trying to understand chiptuning at modern cars and their checksumm

[Cloudforce]

Hello

i?m a little bit overwhelmed with checksumm in newer ecu.

i found a Tuningflash here which is called 330Ci_Softronics_v1. its allegedly tuned for cold air intake and headers.

so i took kwp2000+ interface, downloaded file from my ecu and saved it (luckily).

i then uploaded those tuning software and after flashing the DME had can-timeout resulting in faultcodes and error lamps.

i reflashed the old file and the ECU worked fine.

so i was thinking about those checksumms and if there was maybe something different.

i opened winols, imported my stock file, imported the tuning file and of course winols found differencies in the checksumm. its been corrected by winols and i saved the file as M54B30_Softronic_chk-okay

again i tried to flash it to the ECU and again the dme failed after the flash. i got an error lamp in the steptronic-display.

i reflashed the stock file and its been working fine.

what could cause this manner and how do i get rid off it?

i would be really thankful if anyone could point me in the right direction or could teach me what went wrong.

i will attach the stock dump, the tuned dump and my faulty try to correct checksumms.

kind regards and many many thanks :)

[oldford]

Well, it's not the checksum that is causing can-bus errors. That would be incorrect software, crashed software, wrong changes, etc. etc.
With a checksum error you would be getting something like a P0601 error code or 2830 if you read BMW specific.

You're lucky you got those errors immediately. Otherwise you would have been out for a test drive and might have seriously damaged the engine or the cat's.

[Cloudforce]

i?m logging constantly all values available from the ecu and cats don?t really matter, the will be changed next week to underfloor cats and header.

so if its not the checksumms, what could it be? :afraid:

does it maybe matter that i have auto trans and maybe the software was written for manual only? does that sound plausible?

[oldford]

That would be incorrect software, crashed software, wrong changes, etc. etc.

I think I already answered your question.

Dump this so called tuning file unless you want to blow the engine.

[Cloudforce]

well, as technically interested guy who i am, i?m interested to see why exactly it happened.

so i took the whole dump from 29f400 before the "tuning" and after and loaded both into winols to see the differencies.

to me, with minor to none tuning skills, it looked like the tuning file itself is not bad at all, but it seems there is somekind of offset between the original maps and the tuned ones. maybe thats the problem?

i?ll attach both files if someone wants to have a look at :)

:bounce:

[Cloudforce]

i?ve got an reply from a tuner who pointed me in the right direction:

Even if the maps are same between different MS43 versions, there are always offsets between them.

so that seems to be the correct answer, as i was trying to upload the map dump from my spare ecu to my first ecu, which produced exactly the same problems and warning lights as with the tuning dump.