Knocking noise and light smoke

[autocrazy]

Hi  newbie here   I bought my new to me 2.0d X-Type 2 days ago.  Last night when I drove it, I could see smoke in headlamp of cars behind me. So this morning I investigated. The smoke is black and very light, only can be seen by flooring the accelerator pedal. I also noticed knocking noise some times at idle, more pronounced at full steering lock (power steering pump load?). Other than that, the car drives a hoot, almost too well - I am suspecting it's been chipped because performance is amazing for a130ps 2L engine.  It's not been serviced in 12k miles (3 years as it was stood for the last year or so). I will ofcourse get it fully serviced in next few days, but was wondering if I need to resolve the smoke and knock issue first?  So what should I be looking at?  Having read several threads searching for the issue it could be a) EGR blocked, b) injectors or c) service as fuel filter, air filter, Oil and Oil filter nay be bad?  The other issue I noticed was Oil around injectors, it was not fuel as the consistency was of oil and gas no smell. Is this just over spill while filling (I suspect not as the oil was black with carbon like used oil). I have cleaned the area and shall monitor, but wondered if all this was linked?