exdos said:
What happened to the engine?.
Final diagnosis was that an intake valve on #1 cylinder was bent - which I believe was caused by the BMW Assist 'technician' who came out to the car when it developed a misfire and showed a yellow EML light.
The lady on the phone told me it was perfectly safe to drive to the nearest dealership, but I insisted on a technician/recovery. Finally a technician arrived and spend 45 minutes revving the nuts off it to 'clear' the misfire that was probably due to dirty plugs (they weren't as he took them all out), or dodgy coil (swapped them all around and the problem persisted). Strangely the computer showed an ignition fault on #2 & #4, not on #1 where the problem was found to be. I think it was probably just a O2 sensor, but the actions of this technician made it much worse.
Originally they said a plug electrode fell into the cylinder and caused lots of damage, then took it apart and said it was valve damage, then took some more time and said it was something else, and something else.
In the end I stopped listening, and fought for 6 months to get a copy of the invoice of work carried out so I could put it in my service history. Took a drive over there (it was in Colchester and I was in Liverpool) on a winter's day (when half the staff were off and the were closing at lunchtime) and got a junior to make me a copy. I heard on the grapevine that he got a bollocking for doing so, as there was stuff on there that they were trying to charge to me AND to BMW Warranty.
In the end the whole cost was covered under warranty bar an hour or two of labour - and I couldn't be bothered arguing over that as I'd got my £3500 'investigation deposit' back once I'd proven it had been paid for by BMW Warranty (hence my need of, and their reluctance to supply me the warranty invoice).