DPF with dirty engines

sevenhills

I can understand that a DPF copes well with modern clean engines, but once the engine has done 100,000 miles, what then?
I recall buying an ex police Astra that would bellow smoke if I put my foot down. In that instance would the life of the DPF be massively reduced?
My 115,000 1.7 diesel is a little smokey. Is a DPF like an air filter that gets full or clogged?

Barkin

Yes, DPF's do get full/clogged. 
Smoking though won't be because the DPF is clogged, but unless you rectify the reason for the smoking the DPF will very likely get clogged as a result. 

400ixl

DPF's have an automatic regeneration function where a process is undertaken to burn off the soot collected in the DPF, clearing it out. There is a small amount of ash that can be left behind which will eventually fill the DPF but that takes a long while.

Smoke whilst under hard acceleration either means it is over fuelling or is burning oil. It would mean that regenerations are required more frequently, but provided they happen and complete then it shouldn't shorten the life of the DPF drastically.

Goudy

Does it have a dpf, what year is it?

Generally excess black smoke from a diesel is a fuel air imbalance.

White smoke is usually unburnt fuel.

Blue smoke is oil.

Common problems with higher mileage diesel that will cause excess black smoke when acellerating is the egr valve.
It it's failing is will allow exhaust gas to recirculate when it shouldn't, like acellerating. This chokes the burn as it takes air away from combustion hence the black smoke.

Higher mileage diesels suffer as the valve can clog with soot in the recirculated exhaust gas and oily vapour from the crankcase breather that is plumbed into the air intake over time and mix into a horrid thick black gunk.

Another issue could be a split hose after the turbo. Air leaks away so you are left with a rich smokey burn.
You usually notice a whoosh as the pressurised air leaks out and the car will be down on power.

chrisw

For all the faults of DPF, I think we have become used to 'non-smoking' diesels. I had a band new VW Passat in 2006 which was just pre-dpf and which produced clouds of black smoke if you put your foot hard to the floor.

fordyms

Put a DPF cleaner additive in a full tank and go for a long motorway drive of 100+ miles, see if that sorts it out. If the whole system is clogged (EGR, Manifold & DPF) might be worth a carbon clean from a specialist.  I use a DPF additive & premium fuel in my Insignia every 2-3000 miles to keep it running as it should.