Re: Motronic Control Unit

[Dave Mulhouse <mulh0021@xxxxxxxxxx>]

I happen to have both of the MCUs you are talking about.  You can chip
the 021 MCU.  There is an EPROM socket, but it will not take the same
chip as the 027.  (Might be same physical chip, but different software.)
I once asked Conforti if he made a chip for the 021, his reply said that
the computer architecture of the 021 is completely ancient and not worth
dealing with.  Other chip vendors may make a chip for a 021, but I did
not look into it.  I believe the 021 and 027 are interchangeable, but
only Jim Conforti could answer that with authority.  Jim has a useful
DME application chart on his website: 
http://www.bonnevillemotorwerks.com/bmwchips.html

If you decide you need a 027 MCU, I would be willing to sell you my
spare.  Make me an offer.  Also, your MCU may be repaired.  Do you know
what part of the MCU went?  What where you testing when you killed it? 
If the MCU is in fact dead and you want to repair it, you will need to
check for blown components.  Some possibilities are: fried PCB traces,
cold solder joint cracks, blown diodes, blown transistors, blown power
transistors (the big ones), blown digital components, and much much
more.  You might get lucky and find a visual clue as to what went out. 
If not, you will need some electronic background and electronic test
equipment to go any farther.  I would first try the 021 MCU in you car
to prove that the 027 is in fact dead.  If it is, open it up and look
for fried components.  If you can't find anything, and you want to reuse
you performance chip, find a 027 MCU.

Good luck.

>Date: Sun, 16 Jul 2000 22:54:20 -0400
>From: Al Waschka <awaschka@domain.elided>
>Subject: Motronic Control Unit 
>
>In the process of diagnosing a problem with my ignition, I believe I
>killed my Motronic control unit.  My car is an 85 325e.  I have located
>an 84 325e control unit, but the part numbers are different.

>My unit has a Bosch part number of 0 261 200 027.
>The unit from the 84 has a part number of 0 261 200 021.
>
>Are these units compatible?  Can I just put my chip in the 84 unit and
>effectively make it an '85?
>
>If not, does anyone have the capability to test/rebuild these units?
>
>If not, is there a reasonably priced source of supply?
>
>I will be publishing my method for replacing the reference sensor pin as
>soon as I can get a control unit to verify that the fix was successful.
>
>Thanks,
>
>Al Waschka
>BMW CCA 104964

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