Hacking the Motronic ECU (Audi RS2)

[prj]

Talking about VSS, from the ECU pinout, it looks like there is VSS also going into the ECU.
Does anyone know whether the main (80C535) chip has access to it?

[prj]

The reason I am asking for this, is because I want to create a launch control function.
I can create it now using load and tps, but with the VSS in the equation, the algorithm could be much better.

http://www.youtube.com/watch?v=aaiCZKp0w6Y&fmt=22

[prj]

Let's post some more info regarding Motronic in general.
This time on the topic of load, the MAF and fueling in Motronic.

So what is load?
Load inside the Motronic ECU is the injector time open to reach lambda 1.
It is calculated from the following:
1) Engine RPM
2) Mass airflow (kg/h)
3) The injector constant programmed into the ECU.

The formula is:
LOAD = Mass Airflow / (Engine RPM * Injector constant).
Of course, this is a bit simplified, but that is what it boils down to.

Fueling
The main fueling map in motronic is an enrichment map. It is a basic multiplier map, that either increases or decreases LOAD (injector time open) based on RPM and LOAD itself.
Let's take a look at the stock AAN fuel map:

Now, if we have set our injector constant correctly, then 1.00 will be more or less close to stoichometric.
If we know how much our injectors flow, we can easily turn this map into a target AFR map using basic math.

The MAF
So, why do our cars use a MAF? It is because the MAF allows us to set an AFR target without running closed-loop with a wideband. This is not really an issue now, but it was back then.
Basically it makes fueling in motronic very easy to tune, as you can just punch in target AFR and the MAF will get you there. Of course it is not 100% perfect, but it is a lot easier than using a speed-density system.
An additional wideband O2 sensor is always useful though, as it can be used as insurance.

[bimmerboy]

Prj seems you have made great progress on this. I'd love to start getting setup for this, can you share some helpful links you used to read up on this? I'm sure with a little more reading and actually trying it with a trace it will make a lot more sense.

[prj]

Most if not all the links are contained in this thread. But you will not learn enough from links.

[Jonas_R]

Quick question:

If I wanted to adjust the fuel offline at 4800-7000 rpm what would I need?

I got the eeprom eraser and burner, but wondering what software could be used to edit offline?

[prj]

I use TunerPro, but adjusting the fuel map will not bring you much if you do not understand load and how motronic works, as you won't know which cells to adjust.

Plus, it's just not feasible to tune the car that way. Get an emulator if you are remotely serious about this.

[Jonas_R]

I could buy an emulator, but it would be overkill since all I want is a bit more fuel at the top end.

The car has a map made by a tuner but seems to be just a bit lean 0.84 at the top end and I wanted to add just a little more fuel. So reading your above post I assumed it was a matter of changing the fuel map values.

[prj]

I could buy an emulator, but it would be overkill since all I want is a bit more fuel at the top end.

The car has a map made by a tuner but seems to be just a bit lean 0.84 at the top end and I wanted to add just a little more fuel. So reading your above post I assumed it was a matter of changing the fuel map values.

Ok, and which value are you going to change?
The map is 16x16, not 16x1. So how do you know what the load is where it is running lean? Especially if it is only one spot.

You don't... and if you change everything at the same time, you will run mega rich in some transients.
If you think a 200 EUR emulator is overkill.... then go to a tuner.

[Jonas_R]

Thanks for the help mate. Much appreciated!

[prj]

Thanks for the help mate. Much appreciated!

Don't know if that is sarcasm or not, but the only way you can find out which value to change offline is to know LOAD and RPM where you are running lean.
And even then, unless you understand Motronic, you will not know how much to change the value... and even if you do... and it is the last value in the table, you will STILL have to find it by testing...

This is why I am saying you /need/ an emulator.
Taking out the chip out of the ECU takes a lot of time... of course you could use something like this (which I use because I don't have two emulators):


But without the emulator, you still will have to each time stop the engine of the car (not good for the turbo!) take the chip out, erase it, burn it again, put it back, start the car... not feasible.
Get the emulator (Ostrich 2.0), and I can tell you where and how to change the table.

[newborg]

RS2.xdf

I have been playing with the RS2.xdf
on Audi RS2 0261203543 1267358668
Did I do the right? The 8406rpm seems high?

Title ="Rev Limit - Stop Fuel"
Address =0x3B0
75h=117
983600/117=8406rpm

Title ="Rev Limit - Re-start Fuel"
Address =0x3B3
80h=129
983600/129=7524rpm

[prj]

Stop looking at that .xdf.
It is useless, it is just a xdf from another car... it contains no useful information.

[Dybro]

disassembling AAN-code.....

Has anyone tried disassemble the the binary-code and found some interesting stuff??
At the moment I'm fidling around with ida-pro and the AAN binaries. But I don't know much about disassembling, assembling-language or the motronic 2.3.2 pcb.

Is such an attempt trying understand motronic just waste of time...? If not, I would be happy if someone could supply me with some useful info.

Thanks

[prj]

Has anyone tried disassemble the the binary-code and found some interesting stuff??

Sure. I even had to rewrite some bits of it...

At the moment I'm fidling around with ida-pro and the AAN binaries. But I don't know much about disassembling, assembling-language or the motronic 2.3.2 pcb.

Is such an attempt trying understand motronic just waste of time...?

For you, perhaps yes, since you lack the necessary skills. 8051 instruction set is tiny though...
That said, you don't need to disassemble anything to tune.

If not, I would be happy if someone could supply me with some useful info.

What are you trying to do?