Strange Electrical Gremlin

[myles]

Guys, I need your help. Old Bob and I have been looking into a problem with his car (89 525i M20 auto - Japanese import) that he has posted about here in the past. This is a strange intermittent problem that is showing up in a few different ways -

1 - The engine starts to miss fire and runs rough.
2 - The check control display, the odometer and range display go . It starts by displaying Trans Prog and then progresses to display garbled rubbish.
3 - The relay inside the transmission computer (EGS) starts clicking on and off frequently and randomly.



The instrument cluster is ok, the battery is charged and is ok and I have had a look at some of the earths which appear to be ok. We have also cleaned the electrical contacts on the EGS computer and transmission.

I have found one strange modification to the car that I'm not sure if it has some effect on the problem. This relay and fuses(fuses removed when the photo was taken) have been installed in the e-box.



If anyone can tell us what the writing on the relay says - we'd love to know.

The wiring from the relay appears to go into the wiring connector for the engine ecu. The other strange thing about the ecu is that the vin number on the sticker on the ecu does not match the vin of the car. According to the etk it is from a USA E28 535ia.

I don't know where to start with this problem. Has anyone got any ideas?

Cheers

[Ausmpower]

Sorry I can't shed any light on it.

Imports suck...... especially when modifications are made prior to import....

What numbers are on that ecu?

[shogun]

The japanese writing on the relay means "Main relay II"
http://s71.photobucket.com/albums/i1...gAnch=imgAnch1

But I have no idea what they did with it and why they installed it. You have to check where the wires go and where they come from.

Let us know the complete number of the E 28 USA ECU, Bosch and BMW. Then we can check if that is compatible.
And maybe someone with the same car can check and tell us what his MOTRONIC number is.

[myles]

Thanks for your input guys.

Thanks for the translation shogun! I hoped you would see this post. Can you tell me if the relay and fuses are normal in a japanese model? I wouldn't expect them to be.

The Vin # on the ECU is 1722877 and it has bosch part number 0 216 200 380. Someone has written on it in black pen "525i"

The wiring comes from the +ve terminal on the battery, through the fuses to the relay and then into the wiring harness connector for the ECU. I also noticed that there are a few small screws on the front of the ecu case that my ecu does not have. I'm not sure if they are used to hold the cover of the ecu on, or if they are holding some sort of daughter board in there. Might be some strange performance chip type of modification.

I'm starting to wonder if maybe we should track down a correct ECU, remove the relay and fuses and see how it goes. That will be a bit costly and may not help with the problem.

[myles]

Does anyone have any more ideas on this problem?

[rob101]

The Vin # on the ECU is 1722877 and it has bosch part number 0 216 200 380. Someone has written on it in black pen "525i"

that isn't a VIN it is the last 7 digits of the part number 1722877 bmw loves doing that i have noticed.
i refer you to a post on another board by someone whom you may be familar with http://www.bimmerboard.com/forums/posts/93519
according to shogun it is for a 325i which is still an M20 but i'd assume the loom is different which would explain the psycho relays.
just a theory

[myles]

On my car's ECU the number on the same sticker is my car's VIN#

The bosch part number certainly matches up with a motronic 1.3 for a M20B25.

[shogun]

That is definitely not standard on Japanese cars, the arrangement of the wires is not really factory like.
Have talked to a friend and he also thinks that it is some kind of tuning style, but he also does not know the details.
For the electric experts (not me) it might be interesrting to know where the wires are connected on the ECU, someone should then have a pinout of the ECU or you have to check the wiring diagrams, it should be possible to find out the ECU pinout.
I have the one of the early M70 MOTRONIC and the 1.3 version
http://www.bimmerboard.com/forums/posts/155581/

[rob101]

On my car's ECU the number on the same sticker is my car's VIN#

The bosch part number certainly matches up with a motronic 1.3 for a M20B25.

http://www.pelicanparts.com/bmw/tech...DME-Repair.htm
i am really starting to think, that he has an chip meant for an e30 in it and this is the problem.