Basically, my DS3 1.6 hdi has done 112,000 miles and has been getting gradually worse emissions readings on successive MOT tests. Last year I had to take it away to do an "Italian Tune Up" on the road to burn some crap out and then take it back to the test station, on which it passed. This year, a couple of weeks ago, I did the same before taking it for the test (then the clutch failed on the way but that's another story) and it passed the test but the emission readings are still quite high.
The exhaust pipe was always quite clean until, maybe 18 months ago, when I noticed it getting sootier and not smelling as sweet as it used to. Now it chucks out black smoke when picking up speed off a roundabout and similar situations. There have been no engine management faults thrown up and a basic plug in tester indicates no faults either. I do have the Diagbox equipment, but the refurbished laptop I bought to install the software on for use on my old C5 Tourer has now decided to die.
There is a bit of oil going into the turbo from the PCV valve on the engine top cover and there are a few fumes burbling around the PCV valve and i am waiting for a new one to arrive. That thing - a rubbishy plastic cover with a couple of springs, a diaphragm and a little valve seems a "not very good" design to me. All oils and filters have been recently changed and are changed regularly...so the air filter is clean.
I have been watching videos on YouTube about cleaning EGR valves but they all seem to be on Peugeots, with the job looking a lot easier on them than on my car, especially since the valve on mine is combined with a water cooling assembly and I don't really know how it all comes apart. I have been having a look at the job but there seem to be a lot of gubbins to remove and put back on, when I might only find the valve to be clean. I know there are other things like the DPF and probably other reasons for the smoke but I haven't thought about them yet. The car runs perfectly with no other complaints other than this black smoke, which I would obviously like to sort out. I was a full time Citroen independent specialist for around 25 to 30 years (when life and cars were simpler) and I still try to do all my own work, for reasons of satisfaction and economy, but I am just wondering what my next logical step should be with this problem. I am hoping someone here might be able to give me a clue, please. Thanks in anticipation
