Fried DME?

[Boost Junky 1]

Hi all, been a long time =)

Ok so I have been installing a M52B28 into Jamie W's E30 face lift. The other day I made the mistake of shorting a main +ve battery wire on the case of the DME. It sparked and marked the case, how would one go about determining if this caused any electrical damage to the DME?

We now have the vehicle at the stage of turning it over

- The fuel pump has power and is turning over and is supplying fuel all the way up to the injectors.

- The starter motor is cranking

- ICV is running

We have sprayed ether through the intake which seems to ignite so we are getting spark of some sort. We pulled the fuel rail off and cranked the motor over and the injectors are bone dry and nothing is spraying out of them. Also we are running the M50 DME and M50 Engine loom, the only thing that is still M52 is the coil packs and Injectors, are they compatible with the M50 DME?

Can anyone suggest a solution here?

Cheers, Luke

Edited July 20, 2012 by Boost Junky

[BM WORLD 1286]

vanos m50b25 have the same injectors as m52b28 etc ,

all coils work the same as well.

make sure you are using the m50 crank and cam sensors

i would say you might have killed the ecu

have replacement ecu's if needed.

[Greg111 13]

Ether fires on compression alone, no spark needed so you may not have that either.

I assume this doesn't have EWS?

[Silver Fox 43]

It sounds like you may have a crank sensor failure and the engine dme isn't getting the tdc signal to open the injectors, either sensor or position?

Had this with the m52b20 running on the M50 loom, also on the m54b30 if I remember rightly as well.

[Boost Junky 1]

vanos m50b25 have the same injectors as m52b28 etc ,

all coils work the same as well.

make sure you are using the m50 crank and cam sensors

i would say you might have killed the ecu

have replacement ecu's if needed.

Yes they are M50 crank and cam sensors thanks Brent and I have swapped them around with no success.

Ether fires on compression alone, no spark needed so you may not have that either.

I assume this doesn't have EWS?

Oh right I was not aware of that, nah there is no EWS on this system.

It sounds like you may have a crank sensor failure and the engine dme isn't getting the tdc signal to open the injectors, either sensor or position?

Had this with the m52b20 running on the M50 loom, also on the m54b30 if I remember rightly as well.

Oh right, so your saying that the sensor is either incorrect or in the wrong position? The sensors are definitely M50 sensors.

Thanks everyone.

[Silver Fox 43]

Possibly Luke, are you sure your cam's not 180 degrees out?

[Boost Junky 1]

Possibly Luke, are you sure your cam's not 180 degrees out?

David, the motor hasn't been apart. Just looked at the sensors now and there's no way we can accidentally put the cam shaft sensor in place of the crank shaft sensor and vice verso. I'm beginning to think the ECU is goners.

[polley 916]

Try the ECU in another car, best way to check it.

While cranking the engine the fuel pump is running correct? If so, the DME is getting some sort of crank signal - it only runs the pump while it is receiving one.

Pull a plug and check for spark - its the easiest way to confirm it.

Also, does anyone have a m50 trigger wheel to compare to a m52 trigger wheel? The missing teeth may be in a different location.

Edited July 21, 2012 by polley

[Boost Junky 1]

Try the ECU in another car, best way to check it.

While cranking the engine the fuel pump is running correct? If so, the DME is getting some sort of crank signal - it only runs the pump while it is receiving one.

Pull a plug and check for spark - its the easiest way to confirm it.

Also, does anyone have a m50 trigger wheel to compare to a m52 trigger wheel? The missing teeth may be in a different location.

Troy, yep the fuel pump is running. To make sure, we bypassed the Fuel Pump Relay and supplied a constant 12v to the fuel pump while we cranked it over. I better make sure the fuel pump is running (wired up correctly) while turning the motor over, your saying this will confirm whether the DME is getting any kind of crank signal right?

I shall pull a plug and check that also. We do not have another BMW to try the DME out in, is there anyone local (New Plymouth) on this forum that may be willing to help?

Thanks Troy

[Silver Fox 43]

Yes, the gap is different on the M52, fires the injectors at the wrong time, got caught there too now that you remind me.

Get a m50 trigger wheel and check tho.

Edited July 21, 2012 by Silver Fox

[Boost Junky 1]

Ah so we need an M50 trigger wheel then?

[Silver Fox 43]

yep

[Boost Junky 1]

Well no point wasting the rest of my Saturday off then is there

Regarding the M50 trigger wheel, has anyone got one for sale and $$$ please?

I presume this means removing the crank pulley

[Silver Fox 43]

6 13mm bolts, not a biggie

[Boost Junky 1]

Ah my bad. By the way we also havn't got the two knock sensors wired in either, I presume they dont have to be plugged in for the DME to operate correctly.

Do the M50's even have knock sensors?

[Silver Fox 43]

I don't use them either

[polley 916]

Knock sensors are no biggie.

And yes, I meant check the fuel pump is running while cranking (and wired correctly) to confirm ECU is getting crank / trigger signal.

I'm pretty sure there is no difference in trigger wheels between m50 vanos and non vanos, only between m50 and m52. But either way you will need the correct one.

[thorburn 121]

There is most definately different trigger wheels between m50 Non vanos and m52 trigger wheels.

I'm quite certain that the trigger wheels on the m50 vanos and m52 engines are the same. And a quick check on realoem also shows this.

Removing the crank pulley also requires removing the big f**koff bolt on the front. Which is also supposed to be a one time use bolt

[Silver Fox 43]

Some you have to remove, but some have the trigger on the front and you can just change them with the 6 bolts.

The m54b30 we used from an x5 and the m52b20 from an e46 were both easy 6 bolt ones.

[polley 916]

All M50 ones I have seen do not need removing of the large hub bolt to remove the harmonic balancer / trigger.

[Greg111 13]

Correct, also the triger wheel can deform which will cause the car to not start/run very oddly.

I replaced one on an M50 Vanos a few weeks back for these symptoms, as above, remove the six 13mm bolts on the outside and it will come off with persuation.

[Boost Junky 1]

So the M50 Vanos and M52 Vanos trigger wheels are the same then?? I hope not as I have already ordered an M50 Vanos one haha..

Sweet I wont worry about the knock sensors then and will check the fuel pump once over again. I had a descent look on Sunday and yea it was just the 6x 13mm bolts to remove the trigger wheel, piece of piss.

Thanks for all your help guys!

[Silver Fox 43]

Nah Luke, the m50 and m52 have the trigger points in different places.

[BM WORLD 1286]

Nah Luke, the m50 and m52 have the trigger points in different places.

are you refering to m52tu (twin vanos) engines which are different to m52 single vanos

my mate fitted a m52b28 engine from a 96 328i into his e34 525ix touring ,

everthing was swapped across from the old m50b25 engine onto the m52b28 engine

all works pefectly fine.

just used all the m50 electrics etc

[Silver Fox 43]

Yes, m52b20tu engine.