Smokey engine & going into get you home mode

[Kimican]

Hello everyone, I am a new member (today) I have owned my lovely 2004 (facelift model or so I was told) silver C220 automatic diesel estate. I've owned it since March 2015. It was very smooth and powerful until a month ago, now it still starts first turn of the key no matter what the weather/temp as it always has done. BUT now when I use kickdown or accelerate hard in any gear it kicks out a lot of black smoke for a few seconds then clears until I accelerate again and after it's driven say 8 - 10 miles and I pull up at a junction or roundabout it also goes into 'get you home mode'. But if I pull over and turn off the engine, then restart it it drives fine again for a few miles.
There are no warning lights coming on and it's not only annoying but very dangerous at junctions etc. I think it may be the Particle Filter, so I drove it down the M1 for 15 miles whilst keeping the engine at 3000 revs (I drove it in the early hours of the morning for safety)
A friend suggested that it could be the heater coils as they are supposed to burn off the crap that the particle filter collects, he put it on his engine analyzer and it only verified that there was a problem with the particle filter and said nothing about the injectors or the heater coils.
So if anyone out there has any ideas I would be very grateful, especially as it's M.O.T. is due in Feb 2016.
Thankyou in advance for any help, Kimi.

 

[BlackC55]

Have a look at my thread in the engine section.

 

[Kimican]

Thankyou, but I live in Maltby, South Yorkshire. A bit too far to travel especially with the problems it has, Kimi.

 

[flango]

Thankyou, but I live in Maltby, South Yorkshire. A bit too far to travel especially with the problems it has, Kimi.

I'm from Rotherham originally and used to work at Maltby, ETS auto centre at Bramley are competent with Mercs they did some work on mine when I needed diagnostics and some suspension work that needed a ramp. They are just past Morrison's thru next set of lights on left. Owner runs an ML and SL they also do MOT so you might kill two birds with one stone