Help needed please E46 Clattering

Hi All

First post as never had any issues with the car before :-(

E46 330ci (2003)

A few days back it started to sound more like a V12 and very lumpy. As I was being dropped off, the EML came on, so got it recovered. My mechanic came out and put the box of tricks on, and it said all 6 cylinders were mis-firing, and both O2 circuits.

He took away the coils to test, and 3 had in fact failed, so replaced all 6 and new sparcs. There is also a loud clacking sound from under the ar, and we thought it may be the CAT, but on getting it up on a ramp, the clacking is coming from the gearbox.. Sounds like a ball in a tumbledryer while idling.

Finally, on pulling away from the exhaust centre, the EML came back on.. Car drives ok, gear changes are ok, no miss-fires that Ican tell, pulls like a train as always.

Any ideas. I would rather not put it into BMW, as wallet not bottomless, but could also use a local mechanic if anyone has one in the Fleet/Farnborough area.

Thanks

Tim

Not sure if this is relevant, and certainly doesn't fit with the gearbox clacking, but a couple of years ago I had a problem with my old 330Ci that proved to be a combination of some dodgy coil packs and a throttle body problem.  Both of these are known problems. 

The symptoms were that the EML and emissions lights would come up.  If the car was running on cruise it would disengage and the car would drop in to limp home mode.  Typically turning the ignition off and back on (a re-boot?!!) seemed to clear it and it could go a couple of days before recurring.  Over a week or so the frequency of occurrence increased.

My specialist took it in and diags initially pointed at 2 coil packs.  Having replaced those the prob did not go away.  At this point he suggested replacing all coils as the codes can be a bit misleading.  Even then the prob didn't disappear.  He speculated on a failed cat but were able to test a known good exhaust and cat (coincidentally my sister had an e46 328i Touring - that we now own - that had the exact same exhaust and cat part numbers) but the prob remained.  The throttle body was next and a second hand replacement from a breaker sorted the remainder of the problem.

I suspect that the coil packs may have been degrading for a while but the throttle body was a later addition to the list of problems and the one that tipped it over the edge.  After all this the car drove more smoothly than ever before and had no more issues.

As I said, not sure its a direct fit for your problems, but it might help point you in a direction.  It sounds like you need someone that is good on the good old fashioned (but fast disappearing) art of diagnostics, using codes and experience together.