M54 electronic problem... help !

[clipper]

Already posted this in BMW5 forums but I know there are some knowledgable people kicking around here so...

My 525i E39 started playing up, like a misfire, shuddering at idle, not revving freely and generally wheezy (struggled to maintain 60mph up some hills on the motorway), engine symbol light was on on the dash.

Took it to an indy agarge who are usually pretty good, often see BMs Mercs and the odd Porsche in there. They drove it, said it was fine, cleared the codes, drove it again, no light, no problem so handed it back to me....

A few days later the problem is back so I take it back to the garage and they have now said that according to their diagnostics it's the ECU....

I've been told though, that an ECU fault would cause the EML light to come on.

I don't think the garage is on the stitch up, just maybe that they're a bit out of their depth.

What would you do ?

[Linglong]

Ask for the fault codes and descriptive text and il help you best i can with possibilities that are causing the symptoms

[B7]

These can suffer from disintergrating breather hoses and oil seperator problems. You may be experiencing loss of crankcase pressure? I'd check that first. But I would expect there to be some spotting of oil on the floor as well.

My moneys on a faulty coil pack?

Wait for BSS325i to come along. He may know more bein a BMW techie an all that.

[clipper]

Coil pack went last year and this was succesfully diagnosed and repaired quickly and at a fair price, so if it was that again they'd not be telling me that it was throwing ECU fault codes.
I've checked the breather valve (or at least checked for the symtoms) myself and it seems fine. Even with my limited knowledge of electrickry I fairly sure this is an electrical / elctronic issue.

I will try to get the codes tomorrow anyhow.