Miller Gen 3 MAF analysis

[It's Soda Not Pop]

Am currently using SSSquid Tuning's MCK. According to their site, their maf kit is the only true conversion kit on the market.

[bmwman91]

I interacted a lot with Sssquid in somewhat of an engineering capacity when reverse engineering Motronic 1.7. Jay leaves no stone unturned, and I know that he was aware of the challenges posed by converting an AFM to a MAF without an ECU remap, so he likely put the proper work into addressing those challenges.


@ba114,
In your M40 AFM TF plot, you seem to have reversed the order of the K1 constant array. It should be a nice smooth exponential curve (all Bosch AFM TF's are).

M42 for example:
AFMTF = K1 * (2^K2) * K3
with K1 & K2 being 8 element arrays, values indexed by FLOOR(ADC_COUNTS / 32), and K3 being 32 elements indexed by MOD(ADC_COUNTS, 32)

[ba114]

@ba114,
In your M40 AFM TF plot, you seem to have reversed the order of the K1 constant array. It should be a nice smooth exponential curve (all Bosch AFM TF's are)...]

yep you're right! dunno how i got that screwed up when transposing.

Since you have done a fair bit on this, i do have a question. All the tunerpro xdfs have on the internet have labelled 3x1 2D tables with the axis header "3A" as injector constants. Im not sure thats what it really is.
To me, it makes no sense that it would be a 3x1 table, and even less sense that there would be 2 instances of it.

In the 318i file im working on, these are the decimal values from the file:


To me, this looks more like something that is either in use, or not in use ("3A table 2") depending on one or more of the variant flags in the file. Any advice based on your findings historically?

[bmwman91]

The XDFs for old Motronics on the internet are, largely, full of errors. I cannot recall what descriptor 3A is specifically, but there is effectively no single "injector constant" in these. While there are some constants that do sort of function as flow rate scalers, they do not work under all operating conditions, and the only way to correct for injector flow rate changes is to re-scale all of the fuel maps (of which there are several dozen, multiple copies, some copies used under some conditions, etc).

Tuning the base fuel correction maps and ignition timing maps is reasonably straightforward, although I am not sure how accurate internet XDFs are. In a complete XDF, there are dozens and dozens of filter constants, switch-over constants and stuff like that, on top of the fuel & ignition maps (not to mention several other types). I am no expert at this, and am certainly not a tuner, but I worked with a professional tuner for multiple years reverse engineering the hardware (since that is closer to my professional background) so I at least have a good grasp of the hardware. From what I learned, the internet XDFs are not only incorrect in many ways, but they are missing about 80% of the relevant tuning parameters. It's cool to see people still working on these still, and a number of people have successfully modded the executable code as well as maps.

[nando]

yeah, internet XDFs for the E30 were basically all based on guesses/hearsay, and made by well meaning people who just did what they had to do in order to get by. There's definitely going to be missing maps; there's no way you're getting them perfect without a matching disassembly. Even on more modern, popular cars - say, the N54/335i - the public XDFs out there are just a fraction of what's actually inside the DME, and there are still errors.

The biggest obstacle is there's basically no documentation - I think the "damos" file for early Motronic was basically printed on paper sheets. Most of these were either lost or are rotting in an old file cabinet somewhere - I've only ever seen screenshots of them, I've never actually found any scanned, certainly not for the M20 (I might have seen a partial PDF for Motronic 1.0 somewhere). There's no way, even with a disassembly - you're going to be able to figure out all of the maps without it. It took me 3 years to do it with MSV70, and I had all of the parameters defined in the Damos/A2L. All I had to do was figure out what the offsets were, remap that, and label everything (and by "all", I mean it was still a huge effort).

Contrast that with newer cars, where documentation is plenty - I have basically every A2L for every BMW made since the E90, and most of them since the E46. Most of them don't even need to be remapped because there's a definition for every software version. It's just too bad I don't give a damn about any of them, lol.

[bmwman91]

Well put. Hence why I messed with reverse engineering M1.7 for a few years, and decided to go with a Link E36X lol (not that I finished the conversion yet, but it'll happen someday!).

[ba114]

There are indeed many fuel/ignition maps. It seems many of these are used based on what "variant coding" is set in the file i.e. leaded/unleaded, regular/super etc etc. Interestingly enough, the files provided by MIller are all based on an automatic car...

Anyway, never been one to trust any xdfs on the net, hence creating my own definition files.
I've got most stuff defined in WinOLS now and slowly porting over the useful stuff to romraider.

[digger]

Well put. Hence why I messed with reverse engineering M1.7 for a few years, and decided to go with a Link E36X lol (not that I finished the conversion yet, but it'll happen someday!).

the amount of time one could spend playing around with old junk ECU's from 80's/90's would effectively pay for a top level ECU so a wise decision to get into a different game. Sometimes it makes sense for learning reasons but sometimes not