(Symptoms are massively reduced performance, no power above a couple of thousand revs, otherwise the engine runs just fine, starts well, idles nicely, no overheating...).
The original Cat was a single, siamesed-entry affair, unlike the twin Cats on the 2.8 M52 engined cars...
(Apparently..) The car in question was overfilled with oil & somehow, that got into the Cat, blocking & pretty effectively wreaking it? That's the theory anyway, though I'm not exactly sure HOW the oil would have got into the exhaust. It's not a diesel!
The car has now had the front portion of a 528i exhaust fitted. This seemed to cure the problem, but occasionally, it still does the lethargic performance thing.
When the exhaust was disconnected to confirm the blocked cat theory, it ran fine, if a little noisy...!
My theory is that there is still some crap in the exhaust blocking it further down the system.
Any thoughts or experience of this? (...DunCAN!).
Edited by Trisman, 17 March 2012 - 03:49 pm.