Modifying Motronic 2.3.2 ECU hardware and software.

[vwnut8392]

could someone please explain the basis of the load scale? im confused as to what it is based off of. me and a friend was talking about it and he seems to think its based off of manifold pressure where on the other hand i think its based off of the MAF sensor flow. i also had a thought that it was based off of several sensors like the MAF, TPS, air intake temp etc. basically im trying to learn the reason for rescaling the load axis on the maps basically. i upgraded my turbo and i was trying to find on the scale where where 0 vacuum was just so i have an idea as to where the cross over from vacuum to boost was. this was a method i used to help me tune digifant 1 and i figured it could help me with getting a basic tune decent tune setup for my car. im not trying to go crazy and learn every last inch of this ECU but i would like to do be able to make some basic adjustments to my daily driver if i upgrade parts.

[Acki]

Thanks for the gold dust

[prj]

There is nothing to "misuse".

With stock calibration load is injection time to reach lambda 1.
You can modify the base constant, to keep load that way (even with bigger injectors), but then you have to recalibrate almost all maps, and you will eventually lose precision as well, because the 16 bit load that is used internally is not really *256 to the 8 bit load, the scaling is different.

There is also the base constant from which all further fuelling is derived, this is in some ECU's a configurable parameter, in others it is a hardcoded parameter, but you can adjust it in all of them.

It does not matter what the FR says - for example my speed density conversion motronic is nothing like the FR anymore. It is custom code using the stock hardware.

[Acki]

I'm on the way. Injector Routine nearly all maps "linked".
Next step to check what goes in and what comes out.

I spoke with a friend and he showed me 3 pages of the Funktionrahmen.
Only K1 could maybe "something" what you can "misuse" - I'm not sure.
As you told me, I have to understand every line

Maybe helpful for other. IDAPro disassembles much better readable when I chose the 80535

[prj]

One more time, there is injector constant single value…
There is also a factor for fuel consumption display.

Do not listen to friends too much, disassemble the code, it's in every Motronic with 8051 based processor. In one place or another.

[grundey]

FGAT0 and KHFM, new words for my dictionary

FGAT0 should be Grundanpassungsfaktor and KHFM Grundanpassungskonstante

[Acki]

I think it's important that there is no real "injector size" factor maybe you can add some.
So only "real" factor is used for the fuel consumption signal a friend told me.

But as far as I understand it you have several other factors which you could "misuse" for that.
Battery correction, coolant temperature etc.
What do you think?

[-ice-]

FGAT0 and KHFM, new words for my dictionary

[prj]

Uh… there is single value. FGAT0.

[Kapn.K]

I believe I remember Dmitri saying in one of these threads that there isn't an injector constant. You just adjust the injector duty cycle to compensate. I'm sure he'll chime in when he has time.

[-ice-]

The injector constant could also be a byte in the special block where the rev limiter is...

I think i need an afr gauge now to find it out.

[-ice-]

Hi,

I've got a map which is 4x1 with rpm axis in this "enrichment background calculation" procedure. I assume it's the injector constant. Can anybody confirm this? If it's right, why is it rpm dependant? I know that the battery voltage is a factor for fuel flow through the injectors (there is another map for this...)

Regards

[-ice-]

Ok after looking at some logging data i come to the conclusion that 3D is the highbyte and 3C lowbyte. Like it's shown in the charts below...

3B is also rpm dependant.

[prj]

Yes, you are getting to it.

I will give you a bone:
The two variables you are looking at is the time between two edges on the flywheel trigger.
The RPM limiter is simply a minimum limitation for this time.

3A is just a conversion (inversion) of this time. Because 3C and 3D get smaller with bigger RPM and 3A gets bigger with bigger RPM.

[-ice-]

Hello,

Accessing the x-ram is many times slower than accessing the eprom. I don't know if it would be fast enough if calibration data is stored there.

I discovered the checksum-routine which is called at the beginning of the main-program. It sets dptr to zero and increments it step by step until it reaches ff00. The content of the eprom ist added up every time and stored to register r0 and r1. The values are later compared with the stored checksum values.

and i think i've seen the rev-limiter code(s) in the external interrupt routine. There is not only 3A for RPM...we also have 3D and 3C. 3A is made out of 3D and seems to be "raw data" coming out of the capture counter. Have to look closer at this, but i'm sure it accesses the rev limiter bytes there and conpares them to the ram variables.

Regards