2010 occty VRS noise on engine during retardation, fine when accelerating. But plug number four keeps oiling up and misfires changed PCV still the same, any help much appreciated.

No faults only when it misfires due to oil build up on plug 4. i'll probably make a blanking plate to remove pcv but noise will still be there.

Hi made plate blanked off the pipe work for the PCV and the same thing happened about 100 miles on, as above number 4 covered in oil.

rac been out twice and just want to change coil pack, not excessively using oil though!

Try the coil pack but if it shows oil it seems unlikely. All the other plugs look ok? A fault with the rings on that cylinder? 

Hi looks like a valve stem seal on number 4 exhaust side viewed the build up on and behind the valve head with a boro scope, owe well.

Hi took inlet manifold and injectors off and cleaned out inlet valves and the guides all with excessive carbon on them took a full day on Saturday, now drives like new.