Porsche Motronic and BMW motronic ECU the same?

[MrShades]

Is there any difference of a Motronic ECU unit for a 1984 Porsche 3,2 Carrera and a BMW Motronic ECU unit from the same year?

If there is a difference which i think it might be can you convert a BMW unit to fit a 3,2 Carrera?

[Rot 911]

Check out this thread ECU for 3,2 and try to ignore some of the ranting going on by Lorenfb.

[MrShades]

I also found this about BMW ECU:
Pelican Technical Article: BMW DME Motronic ECU Swap / Repair
DME Swapping

Finally, if you've tried all of the approaches outlined above, and your DME unit still doesn't work, then you will probably have to replace it. A little known secret is that many of the DME units are exactly the same across different automotive manufacturers. The only thing that is different is the programming chip contained within the unit. If the DME unit is the same version of Motronic, has the same connector on the unit, and has a removable chip, then chances are it can be a good replacement for your failed unit. This means that a $10 DME from a Volkswagen in a junk yard may work in place of the $650 one that a BMW used parts dealer wants to sell you. A few customers have experimented with this by swapping BMW DME computers with the ones used on the Porsche 944 and 911, and they have experienced good results. Some units won't work (it's a matter of trial and error), but many will. The main thing to remember is that you have to have the same software version of Motronic, the connector must be the same, and you must swap the chip from your DME to the new one.

[Lorenfb]

"try to ignore some of the ranting"

- Rot 911 -

To respond to the initial post and not like some of the brain-dead that just
post on Pelican to increase their post count and not provide any real info/help,
the answer is NO!

Bottom line: Some posters need to stick to posting on "Off Topic".

"The main thing to remember is that you have to have the same software version of Motronic, the connector must be the same, and you must swap the chip from your DME to the new one."

AND, AND:

The input/output circuitry must be the same. e.g. The same type of driver circuitry for
the SAME type of injectors.

[86 911 Targa]

Originally Posted by MrShades

Is there any difference of a Motronic ECU unit for a 1984 Porsche 3,2 Carrera and a BMW Motronic ECU unit from the same year?

If there is a difference which i think it might be can you convert a BMW unit to fit a 3,2 Carrera?

pm member:

ischmitz

Nice guy, and, very knowledgeable on this subject!

[Tippy]

I have to ask, which cars have the "same" supposed ECU's than the Carrera 3.2?

[Lorenfb]

"I have to ask, which cars have the "same" supposed ECU's than the Carrera 3.2?"

None!

[Tippy]

That's what I thought, but couldn't decipher through the thread easily.

[Quicksilver]

Originally Posted by MrShades

I also found this about BMW ECU:
Pelican Technical Article: BMW DME Motronic ECU Swap / Repair
DME Swapping

Finally, if you've tried all of the approaches outlined above, and your DME unit still doesn't work, then you will probably have to replace it. A little known secret is that many of the DME units are exactly the same across different automotive manufacturers. The only thing that is different is the programming chip contained within the unit. If the DME unit is the same version of Motronic, has the same connector on the unit, and has a removable chip, then chances are it can be a good replacement for your failed unit. This means that a $10 DME from a Volkswagen in a junk yard may work in place of the $650 one that a BMW used parts dealer wants to sell you. A few customers have experimented with this by swapping BMW DME computers with the ones used on the Porsche 944 and 911, and they have experienced good results. Some units won't work (it's a matter of trial and error), but many will. The main thing to remember is that you have to have the same software version of Motronic, the connector must be the same, and you must swap the chip from your DME to the new one.

Lets be specific: No one has traded a 944 DME for a 911 DME and got it to run. There was a thread here about someone swapping a bunch of components (quite a parts list) and they reported getting a car to run. There was no followup to say how it was working later (or if it was working later). That is way outside of a "simple swap".

On to the mentioned BMW DME...
There have been a number of people who have gotten some of the BMW DMEs to run in a 911. Once again the question comes back to, "How long?". As Loren pointed out, the BMW has a different driver circuit for the injectors. What this means is the circuit is going to end up failing because of the difference in current draw between the BMW and 911 injectors.

All this leads to the same place.
You need a 911 DME if you are going to run it in a 911. A hobbyist may be able to alter something else to work but if you have that level of skills you aren't going to be needing to ask here to make it happen.

[Tippy]

Not that I am going to do it or have the expertise, but where is this list of parts to change?

I would like to know more about the electronics of these cars.

[Quicksilver]

Originally Posted by Tippy

Not that I am going to do it or have the expertise, but where is this list of parts to change?

I would like to know more about the electronics of these cars.

Here ya go:
Motronic 3.1 Conversion from 944 to 911.

If you look you will notice that the poster only has 6 posts and never responded when queried about if he got the DME working. (Reminds me to watch that scene from Charlie and the Chocolate Factory where Wonka is saying, "No... Stop..." with the absolute knowledge that no one is listening.) So if you are dead set on trying this you will also have to convert the DME to a 28 pin chip so it is running the code from the chip instead of whatever is burned into the processor.

And if anyone does do this please have the moral fiber to not sell any of them to anyone who doesn't know clearly what kind of frankenstein they are buying. And better yet, until you have a couple test units that have run reliably over 100k miles.

[Tippy]

Thanks for link

[MrShades]

Since there is no follow up on that thread i suppose that it is not working.
It does not help much if you make the car start but that is all