Freelander1 td4 problem

I every one am new to freelanders I have bought one a few weeks ago and I have noticed a starting issue it smokes blueish and idles rough when cold and when oil filler cap is removed smoking stops and idles fine I can't seem to pin point problem it is a face-lift td4 auto 06 plate can any one help with this problem

Regards
Ally

Most likely blocked engine breather filter.
Change it before it pressurises and does damage.
By removing the cap you are relieving the pressure.
It is located under the black cover near to the injectors.

Filters on ebay for about a £5.

Thanks for the reply Andy I will give that ago I have noticed a oil leak at the egr valve take it is being caused by a blocked filter

Check for excess oil in the intercooler pipes. Some is usual, but excess could be turbo seals.
Turbo seals are put under pressure by blocked breather, so could be connected yes.

Do the easy (filter) first, hopefully will be sorted!! Also worth changing turbo vent filter, a couple of quid. It hangs down behind the oil filler cap on one pipe.