Smoking V70 2.0D 2009

[mwinser]

Hi all,

I have a 2009 V70 2.0D (136bhp I think).

Since I've had it, it pumps out a lot of black smoke whilst on the motorway. If I'm cruising at 70 and touch the accelerator a load of black smoke is kicked out.
If I boot it and keep the speed up (over 70mph, on a quiet stretch of course) there is still smoke, not as much as initial acceleration but enough to notice it in the rear view mirror.
If I cruise back to 70 and blip the accelerator the same happens...a load of smoke.

After about a week of driving the exhaust tailpipe will get blacked up with soot. It has the chrome tailpipe so I clean that when I clean the car and its blacked up again very soon.

I've kept up to date with regular oil changes at the service intervals and changed the fuel filter twice (never again though as it took hours to start back up on both occasions).

When I first purchased it I noticed diesel leaking from the injectors. These were replaced and now there hasn't been any leaking.
I'm wondering if the injector fault has caused any issues?

I also blocked off the EGR valve to see if that had any effects on the amount of smoke but it hasn't (I haven't any error codes since doing this so have left it blanked off)

Would the DPF cause this? I assume there is one fitted due to regulations?
I've never seen a warning light regarding DPF.

As far as I can tell there are not split hoses.
I'm just wondering if there is anything else I can do/check before booking it into a garage?
And would it need to go to a Volvo dealership to be checked correctly?

Many thanks in advance,
Martyn