Need Help Finding Computer For 1991 M50 Motor!!!

[beck74]

I am looking for a computer for a M50 motor. I switched out my bad M52 out of my 94 and replaced with a 91 M50. So now I need a computer for the M50 motor. When I started the car with the M52 computer some wires started smoking. Does anyone know where I can buy a main computer for a 1991 M50 motor?

[smcgowan]

What's the bosch number on the side of the unit?

example below...

[Jon K]

Gonna be a 403 I think

[Kai@e34.de]

yes, should be 403 or 405. and btw., your '94 engine is a M50TU, not M52.

hope you also have switched the engine wiring loom, air mass sensor and so on?

[MarkD]

You can use a 405, 403 or 402. The 402 was the last version and then the M50tu used the 413. Why did you even try to run that motor with a 413 ECU? It's completely different, it has VANOS and knock sensors which the earlier M50 does not have.

As Kai mentioned, you need to change the harness also. It would have been much simpler to drop in another m50tu or even an m52.

MarkD

[winfred]

a vanos brain and harness running a non vanos motor should not automaticly smoke, properly hooked up theres a chance it may even run ok (with a obvious vanos solenoid code, unless he swapped in the cams and mounted the servo) i am guessing something wasn't hooked up right under the intake, had a car come a couple years ago that a boat mechanic?! had installed a motor in for the guy that he bought from us that had popped 4 computers one after the other (douchbag ya think he would of learned) turns out he had some sensors crossed up and the computer was back feeding itself and frying various things, computers among them

[beck74]

Thats the problem. I do not have the old ECU from the M50 motor. I just have the M52 ECU. Do you know how I can find out what number I need for the M50.

[beck74]

what do u mean 403 or 405? Do you mean I have to replace the entire wiring harness?

[beck74]

What do you mean 403? Is this number on the ECU itself?

[beck74]

You can use a 405, 403 or 402. The 402 was the last version and then the M50tu used the 413. Why did you even try to run that motor with a 413 ECU? It's completely different, it has VANOS and knock sensors which the earlier M50 does not have.

As Kai mentioned, you need to change the harness also. It would have been much simpler to drop in another m50tu or even an m52.

MarkD
I did not know it would be this difficult. What do you mean by the numbers? Does this mean all the wires have to be replaced? Even the ones that go to the lights and so on?

[Kai@e34.de]

have you read our replys?

1. you can use both, 403 and 405, how mark said. or the 402, dunno, but that's a rare version of the ECU. the 403 and 405 should be easier to find.
2. you don't have had a M52, it's a M50TU! there was never an E34 with M52 engine, the M52 was introduced in the E36 and E39

[Kai@e34.de]

Does this mean all the wires have to be replaced? Even the ones that go to the lights and so on?
not all wires, but i'd change the whole harness, if i were you. the wires for lights and so on have nothing to do with the engine harness.

[beck74]

What numbers are the guys talking about? The last 3? Here is my old ECU from 94. 1 703 808 (its Siemens) So I need one that ends in 403 or 405?

[beck74]

yeah, I read them. I just did not understand the number thing. I am having it fixed by a mechanic and he just told me this is the wrong one. I do not know much about it.

[beck74]

Will this one work?

http://cgi.ebay.com/ebaymotors/E34-BMW-520-Engine-Computer-DME-SIEMENS-ECU-5WK9-001_W0QQitemZ8074272853QQcategoryZ33596QQrdZ1QQcmd ZViewItem[/URL]

[beck74]

I live here in Germany. I am asuming these numbers are the same for Germans specs also?

[Kai@e34.de]

which M50 do you own? 520i or 525i?
please remark that the siemens and bosch motronics are absolutely incompatible to each other! if you have installed a M50 2.0 with siemens motronic and bosch harness, it won't work at all, it's completely different - all the sensors and so on. how i said, see that you'll get to correct harness for the engine that you've just installed!

you still haven't answered my question, if you have switched air mass sensor and so on, too, which belongs to the engine that you have built in right now.

whatever: more details, please. year and model of your car, which engine was that, that has blown up? 2.0l? 2.5l? was a stock bosch or siemens ECU attached to this engine?

[beck74]

It is a 1994 520i. The blown up engine was a 520i.(2.0)(M50tu) The old ECU in the M50tu was siemens. SO I need to replace the harness and find a bosch ECU? No I have not replaced the airmass sensor. Where is this located? Again, I am a beginner at this and dont know all the technical terms. Thanks for your patience.

Matt

[Kai@e34.de]

hi again,
the thing is, that both M50B20 and M50B20TU came with a siemens engine management (not only the ECU but also airflow sensor etc.). how i said earlier, the bosch and siemens engine management are not compatible to each other. but also the ECU for the M50 and M50TU are not compatible. so, forget the whole bosch part numbers.

to cut a long story short, what should you do now? if i were you, i'd take a look for a M50TU engine. not only because the M50B20 is really noticeable flabbier than the M50B20TU, but it would be much simplier for you, too.

take a look in the small advertisements on http://forum.e34.de (kleinanzeigen -> motoren, getriebe & anbauteile (translated: engines, trannies & attachment parts) or ebay. because nearly everyone wants to install a 2.5l in case of an engine failure of the 2.0l here in germany, the B20 engines are really affordable.

if you still want to hold your M50 engine, try to find a M50B20 (not TU) engine harness and ECU from siemens, but i really don't know, which siemens part number you'll need.

where do you live here in germany? if you need help, we guys from e34.de have a few associations here (berlin, saarbrücken, münchen and so on), i'm sure you'll get help if you need to.

[beck74]

Thanks Again,

I live near Ramstein. I have found the Siemens ECU that would work on ebay, but it is 200 Euro. Is there a way you can call me or I will call you? It is much easier to talk on the phone than trying to explain everything here. Here is my number: 0170-217-6774

Thanks,

Matt