Documentary - Motronic 1.7 DIY Reverse Engineering

[petejk]

I think I commented out this code, not because it didn’t work, but because nobody ever used it lol.

I’d be happy to run your file, at the very least it will validate my algorithm, and at worst you’ll be no worse off than you are now. Send me a pm and we can transfer files through email

Thanks, I sent you a PM

[araohfilho]

What a nice job bmwman91 did on reverse engineering this ecu. I'm now working on my own ecu module the with firmware and electronics made from scratch for another model of car. The electronics and the can bus are almost done. But on some areas like short term fuel trim it will be very helful to see for example which sensors were involved on these older modules to get a better idle on my current setup. I've seen some funktionsrahmen on newer ecu's but none for the older ones, does anybody knows if there are any of these manuals around for the 90's ecus?

[bmwman91]

Thanks for the kind words.

I am not aware of any funktionsrahmen in the public domain for these ancient ECUs, although supposedly some people have copies.

Are you going to use "smart" ignition coils with internal ignitors, or will you be using "dumb" coils like the ones in the E30 which require driver transistors?

[araohfilho]

Are you going to use "smart" ignition coils with internal ignitors, or will you be using "dumb" coils like the ones in the E30 which require driver transistors?

Hi bmwman91, the main goal for my prototypes of this ecu is to make a module that can replace the original without any change on wiring or parts, so all actuators, sensors and the can networked dash were modeled and are supported on my current firmware.

The coils are dumb and on another ecu project that i made part of the electronics on 2008, the driver had mosfets and some bjts for driving.

On this project, to reduce board size, the only option for me was to use the ST VB025 driver, its a great driver and give some limited diagnostics, but the driving current must be carefuly calculated before every driving cycle. Thermal are really a problem on this delphi case.

I posted a photo of the current version of the board and you can see some of the choices i made. This version works well on bench up to 8000rpm and were tested on the car till 4000rpm, there are some issues now on idle, and i think that making a proper fuel trim long term will be needed.

Today this project is waiting for me to finish another project and on the meantime i am searching on patents and any document that can help me solve this idle issue.

[bmwman91]

Hi bmwman91, the main goal for my prototypes of this ecu is to make a module that can replace the original without any change on wiring or parts, so all actuators, sensors and the can networked dash were modeled and are supported on my current firmware.

The coils are dumb and on another ecu project that i made part of the electronics on 2008, the driver had mosfets and some bjts for driving.

On this project, to reduce board size, the only option for me was to use the ST VB025 driver, its a great driver and give some limited diagnostics, but the driving current must be carefuly calculated before every driving cycle. Thermal are really a problem on this delphi case.

I posted a photo of the current version of the board and you can see some of the choices i made. This version works well on bench up to 8000rpm and were tested on the car till 4000rpm, there are some issues now on idle, and i think that making a proper fuel trim long term will be needed.

Today this project is waiting for me to finish another project and on the meantime i am searching on patents and any document that can help me solve this idle issue.

That is a very impressive project, I am really happy to see someone taking skills to that level!

Yes, driving ignition coils can be tricky for sure. Aside form having to deal with large flyback spikes on the switched primary leg, dwell current is highly dependent on other system variables and needs to be accounted for to get smooth running. Hopefully you sort out your idle problem. Do you have any posts or anything where you document this project? I would love to follow along!