ECU Tuning for an OBDII S52 swap

[Poeman446]

First of all, I want to thank everyone here for your help so far in my swap. The search bar has answered all but one of my questions. I have an OBDII S52 with the Siemens ECU, and I want to reflash it myself. I understand that its "impossible" but I want to do it anyway. From what I understand, I have to buy a $40 or so adapter to connect it to a computer, and then its all hex editing from there. I want to talk to someone who has done it before, and how it went. I cant find anything really on the subject.

I want to ultimately delete SAP, EWS, and a few other things. I have taken classes in Java, written complex codes for prototyping (in C++) in my engineering classes, and I do EVERYTHING else myself, so why not this too? I understand to pay someone to reflash its around $300.

If someone can lead me in the right direction, I appreciate it.

Thanks!

[Poeman446]

Anyone?

[DesertBMW]

From what I understand, I have to buy a $40 or so adapter to connect it to a computer

No one makes the correct adaptor for flashing MS41, you have to install extra wire and give it switched 12v for the dme to be able to be flashed.

I cant find anything really on the subject.

So you can code C+ but can't use google?

If someone can lead me in the right direction, I appreciate it.

I googled "ms41 flashing tuning" and this is what it popped up

http://www.scribd.com/doc/144024023/Siemens-MS41-Tuning-Guide-pdf

Good enough information for start

[Poeman446]

Indeed I can code a little C+, and I can use google a bit.

I think my main problem was that I didn't know that the '96+ E36 M3 ran a Siemens ms41.2, so I now have that figured out. Thanks for that. When I searched for all kinds of variations including "E36 M3 ecu flash" or anything not including the actual model of the ECU, then nothing DIY came up.

I can add a switched power wire for the adapter, not a problem.

Thanks for your help.

[Poeman446]

Another thing I have not figured out is if I need to get this ECU on the bench, or if I can program it via the Gellatto 1260 cable or If I need to make a new plug to connect to the DME itself on the bench. Basically what I am asking is if I need to modify the 24k code or the 256k code. I am still researching, and finally my exams are over, so i can look in a little more detail.

[Gooch]

I am interested in following your progress.

Where in NC are you? Send me a PM if you're near Raleigh.

[Poeman446]

PM sent. I am going to try and figure all of this out, and If/when I do, I am going to post as much info as possible about it. This cryptic garbage is pretty infuriating. I don't mind putting in the work though. Ill try to keep everyone posted.

[NomadE30]

Let me know when you figure out the checksum problem.


Sent from my iPhone using Tapatalk

[nando]

Correcting checksums is not a big deal, but the OBDII E36 DMEs are not very straight forward and there isn't all that much public information.

the link that HakkenTT posted (DesertBMW) continues his tradition of unhelpful posts - those offsets are for MS41.0, MS41.2 is organized differently so you won't find the same maps at those locations. I've read that document before as well and some of the information inside is wrong anyway.

even finding maps to tune isn't going to be easy, neither is deleting error codes. it's not like there's a thing that says ERROR CODES HERE, it's all just hex bytes and you'll have no idea what any of them are. you'll be looking for binary needles in a digital haystack.

I know the exact feeling you have where you just want to do it yourself (I don't like the idea of having a "black box" computer that I have to pay to change something), but I'm not sure the effort is worth it here when a flash isn't that expensive. Unless you plan on selling your own tunes..

[plain325]

This is $300, but it looks like it might be what you are looking for.

https://www.bmweditor.com

I dont really understand all this stuff, but there is no mention on how to pull the tune from the DME and how to download to it.

[nando]

that's pretty neat, but it doesn't look like it lets you delete error codes or EWS.

[Poeman446]

Thanks for all the support so far everyone. I am about to pull the M20 out of my e30 tomorrow and start the s52 swap. ive got tons of parts together, now its time to assemble it all.

As far as tuning and such goes, I have read for hours and hours on end, and Ive made a little headway. Unfortunately, Im not a computer science major, or computer engineer. I have a Galletto 1260 cable that connects to the OBDII port and will read a 24kb file from the ECU. The full size file is a 256k file, and it must be read by either pulling the ECU entirely or (from what ive heard...) using a BMW tool that sells for around 40 bucks on ebay/amazon. Ive seen some hex locations for disabling EWS, but I'm not sure if its for the MS41.1 or MS41.2, and I believe they have different locations for each accessory (EWS, SAP, etc.) I feel like an idiot because I keep seeing the word checksum, and there are websites to assist in the "checksum issue" but I still do not know what the process is, and what problems the ECU has with a checksum. I will be researching that in a moment. I haven't given up, but I definitely don't have the time to fully understand the different portions of the ECU, and how it all ties together and works. My time is (unbelievably) more valuable than that. Still, I'm making steady progress. I will try to read the 24kb code from my ECU asap to begin interpreting it. If you want to read and learn as much as I have so far, read the link to romraider, and go through the entire thread. It all looks like hieroglyphics at first, but it begins to make sense after a while.

Link to Romraider thread: http://www.romraider.com/forum/viewt...e27773f290dd00


Best of luck to everyone. Thanks!

[Poeman446]

I have received an ENORMOUS breakthrough. I will update everyone if this works, and if not, I will keep working. Thanks for staying interested. I should be able to test this in a few days time.

[ForcedFirebird]

My time is (unbelievably) more valuable than that.

These are the magic words. It takes a lot of time to disassemble the code and make a useable definition file for it.

It's funny, a lot of people call themselves "tuners" because they can find a few maps and functions, and SOME of these people steal others work by reading .bins from other companies/individuals to get a kick start on making their own "tunes" (then when they are asked questions, they act like they are some kind of "tuning god"), but a true tuner can grab any platform that already has a translator (.xdf/definition to interpret the info to a laptop) on any car and sit with a dyno and know what the car needs, not just give a generic "tune" or "chip" that will just run a car.

The German car platforms are the worst for this. Everything has to be a secret. Gone are the days of open source and the reason public information is few and far between.

Looking forward to your progress, I LOVE the DIY crowd...

http://www.e30tech.com/forum/showthread.php?t=98922

[ForcedFirebird]

Ive seen some hex locations for disabling EWS, but I'm not sure if its for the MS41.1 or MS41.2, and I believe they have different locations for each accessory (EWS, SAP, etc.) I feel like an idiot because I keep seeing the word checksum, and there are websites to assist in the "checksum issue" but I still do not know what the process is, and what problems the ECU has with a checksum.

Checksum is a way for the ECU to realize all of the code is present. Lets say you change a value in one of the maps to offset a fuel delivery or spark advance. That will change the "sum" of the entire matrix. In the old days, it was a little more simple and usually just an equation based on all the numbers in the entire file, and if the checksum was wrong, it would only light up the check engine and have a "bad DME" flag/code but would still function normally.

This year I would love to make more time to see what's going on inside the MS4.x, specially seeing the ECU's are abundant here in the wreckers since no one wants to re-aline the DME with the car, whereas OBD1 ECU's are in high demand (and becoming more obsolete).