I have problems with my XC60 T6 (Odo ~80k). Car is running on LPG too.
It idles roughly mostly when cold. When the engine gets warm, it is less protruding. What is more, it registers CEL with random misfires, if is left to idle for 10-15 minutes.
It's not stalling and I haven't noticed any serious drivability issues.
The problem does not appear to be fuel related, although misfires are more common on petrol (possibly due to adaptation).
We have replaced spark plugs.
I have done a smoke test - replaced intercooler as it appeared to have a leak after traffic accident. Haven't confirmed that there are no vacuum leaks after replacement tho (it's on the list).
Today we have plugged the car to VIDA - it appears to register missfires when idling mostly on cylinder 5. We have moved around coil packs, but the most of misfires appear in cylinder 5.
It appears that there is vacuum under oil cap (not really powerful, but you can hear a slight sound once it pops off).
What is interesting is that once the cap is removed, the it seems that additional air entering through oil cap make the car run better - misfires are no longer registered.
My mechanic believes the problem could be caused by faulty PCV oil trap, so I have already ordered the part.
Is faulty oil trap likely to cause such symptoms? Is it possible that, if the PCV diaphragm has failed, the negative intake manifold pressure is directed to top cover causing vacuum in it?
Has anybody had problems with oil traps? I have read that they recommend to replace them routinely.