s40 vvt solenoid

my 1.8 s40 developed a very rough tickover noise. diagnosed as being a faulty vvt solenoid (tickover solenoid) by volvo at last service. vvt solenoid replaced with new one, but no change to the rough tickover. Has anyone experienced this problem ? and if so what is the solution. Car runs very smoothly once the revs are up.

vvt solenoid 

Hi john, Was reading through the forums i know it's been a while since you posted this problem.However i realize you'v had no response and may have diagnosed the problem. By chance if you still have the problem with the noise coming and going and have changed the solenoid it is your vernier pully that needs changing.