I have a 2008 A6 C6 Avant 2.0 TDI 113k miles which is chucking out black smoke from stand still/pulling off.
I cover 60 miles daily (pretty much and mainly motorway).
Ran VAGCOM and found no faults.
Checked four injectors and found no faults. They are also running within spec values (according to Vagcom measured values). SMIC and pipes have been checked for leaks and found none (by garage). EGR gate reported (by garage) to be clear, although not sure if it is chocked up. MAF reports well too.
So far, I have given 2 hours labour to one garage who cannot find any faults, but agree that the car is giving out excessive black smoke when moving from Idle and are none the wiser. No loss in power though!
I thought I might take the EGR off and see if it's blocked with carbon or not, but would that cause black smoke from the exhaust if it was blocked?
Running out of ideas and car isnt very happy Please help.
One other thing, Audi recently did a MOT and service. They changed the fuel pump (recommended). It was smoking a little from what I remember before Audi touched it, but the smoke does seem a little worse since they changed the fuel pump (I think).