Hack and program you own Motronic Chip

[930fan]

Originally posted by d_boyce


Hours and hours of reverse engineering using an 8051 emulator. I turbocharged a 964 which required larger injectors, a pressure sensor and a hot film air meter.


-doug

Sounds interesting. Please tell us more like how fast, how powerful, how reliable and how much. All this motronic editor stuff is very interesting but would it not be more cost effective to just go with a unichip? They can be retuned very easily too and all the installers have dynos so that saves a lot of guess work and gas during tuning.

[ChrisBennet]

Originally posted by 930fan
All this motronic editor stuff is very interesting but would it not be more cost effective to just go with a unichip?

Well where's the fun in that?

[ChrisBennet]

Originally posted by d_boyce

Hours and hours of reverse engineering using an 8051 emulator. I turbocharged a 964 which required larger injectors, a pressure sensor and a hot film air meter.
-doug

Impressive. I've just started on this journey except with the earlier '84-89 DMEs. I'm just using a software emulator and a disassembler.
Did you use/do I need an in-circuit emulator?
Did you tease out the formula just from the code or are there references that you could direct me to on Bosch DME theory/formulas? I've managed to find a little bit looking at some old posts to the DIY_EFI list.

thanks in advance,
Chris
chris@a3ds.com

[Steve M]

I havent delved too deep into this but I wonder how difficult it would be to take all this info and turn it into (x-)*nix capable software.

SMOB

PS-Pay no attention to the 'Senior Member' title underneath my name...with little effort anyone can get that ;-).

[d_boyce]

Originally posted by ChrisBennet

Impressive. I've just started on this journey except with the earlier '84-89 DMEs. I'm just using a software emulator and a disassembler.
Did you use/do I need an in-circuit emulator?
Did you tease out the formula just from the code or are there refercences that you direct me to on Bosch DME theory/formulas? I've managed to find a little bit looking at some old posts to the DIY_EFI list.

thanks in advance,
Chris
chris@a3ds.com

Chris,

I used a disassembler and a freeware software emulator. I also have a very handy EPROM emulator and a wide-band 02 sensor.
There's no one place to get this information really. There are a few good books on theory--DIY_EFI site has a list--but nothing that'll tell you how to tune the IAC pilot control. My favorite books are the Bosch "Red" book and the little yellow Bosch "pamphlets."

I wrote a Motronic table editor that does a decent job at displaying values in readable form. It requires some skill to configure--you need to determine the addresses of the tables you want to edit--You're welcome to a copy of it.

-doug

[ChrisBennet]

Originally posted by Steve M
I havent delved too deep into this but I wonder how difficult it would be to take all this info and turn it into (x-)*nix capable software.

SMOB

I think it would take a lot of effort & info to turn this into a usable piece of software. The more you look into it, the more you'll see how little info we actually have. Basically most of what you've seen was obtained by using Protomotive's DME editor (distrial.exe).
I'm working on this for fun but I have no allusions that if I could edit the DME software that I would be able to a good job of tuning my car with it. After all, years of writing CAD/CAM software hasn't made me a mechanical engineer.
Chris

[d_boyce]

Originally posted by Steve W
Doug,

How straightforward was it to replace the flapper meter with a hotfilm one? Was extensive alteration of the wiring to the air meter required to interface correctly? What about the software alterations - did the fuel tables remain the same however with a linear rescaling of the overall values to match your larger injectors?

I too am impressed with what you did. I would also be interested in a copy of your table editor. Email me at stevekw@pacbell.net.

The hot film meters require 12 volts, the flapper uses 5 volts. You can make a small wiring change at the DME connector to provide 12 volts. You have to add an air temp sensor too. There's one built in to the flapper meter.

On the EPROM there's a "air flow meter transform" table that has to be redone to match the new air meter curve. This is the tricky part and I could never explain it in one e-mail. The response curve of the hot film meter looks a lot different from the flapper and can not be done correctly with the existing code so you really have to re-write some code to make it work well.

There's an air-temp compensation table that has to be "flattened." You don't need air-temp compensation for fuel because the fot film meter is measuring air mass flow.

The newer Motronics with diagnostics require a bit of effort to prevent the new air meter signal from setting error codes but I don't think this is an issue with the '89 and earlier ones.

The fuel tables are for fine-tuning. If the air flow meter transform function is done right, the fuel tables will not require much work to get the car running well.

Reprogramming Motronic for different injector flow-rates is a real pain, especially on the 964 and newer cars. What makes it so difficult is that Motronic uses injector pulse-width to represent load so injector pulse-width is referenced in a lot of places.

-doug

[Steve M]

Something a little better to put in here.

I found a site that has directions for building an eprom reader for 5 bucks:

http://www.zws.com/products/epromr1/index.html

Anyone care to comment?

SMOB

[ChrisBennet]

Originally posted by Steve M
Something a little better to put in here.

I found a site that has directions for building an eprom reader for 5 bucks:

http://www.zws.com/products/epromr1/index.html

Anyone care to comment?

SMOB

Steve M,
The '84-89 units I've seen have used 3 flavors of Eproms:
2716 (2Kbytes), 2732 (4Kbytes) and 27C64 (8K bytes).
The latter one is used in '89 for sure and probably late '87 on.
One of the readers they have will do 2764's but according to them you could modify their circuit to work with smaller Eproms.
-Chris

[jriera]

... and what about a Real-Time EPROM emulator connected to a laptop and you can do modifications to the values in real time... see here --> http://space.tin.it/computer/lorgler/nonst-e.htm or here --> http://www.racelogic.co.uk/emulator.htm

Normal EPROM emulators start at around US $150.00

I have use some of the emulators to debug/modify/customize some of my home video/audio stuff (my other hobby), never for my car (the most advanced electronics are a couple of relays)

Just a wild thought..

[drb930]

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[Mark Dia Gruppe]

drb930, you realize this thread is over 7 years old since the last reply, right??