Got a Passat with a history here. Its an 06 2.0 TDI BWR with a smokey exhaust at idle only. Previous owner put a turbo on it at 90k. Present owner bought it and then suffered from Particuler filter regen problems. The owner then had the filter removed and the management system reprogramed to ignore the lack of filter. Since then its had grey smoke from the exhaust at idle and it stinks,not of oil but diesel fumes,proper eye stinger. It should be noted that the vehicle uses no oil. I noticed it had an intermittent slight mis,so afer doing a quantity comparison test(number 3 was boarderline)renewed an injector and had the others cleaned ultrasonically. Car now runs smoother but dodgy reading has moved to number 1 and its still smokey. No fault codes noted and the car pulls like a train,is clean under accel.I would like to think it was suffering from exess smoke before the ECU twiddle and was masked by the particuler filter before it blocked up.Have just removed EGR valve to check sealing and found the egr pipe(and valve) from the exhaust to be full of that shiney,hard carbon that you get when an injector to head seal leaks to atmosphere.Poss incomplete combustion/leaky valves.EGR appeared to be shut and sealing properly.
Any thoughts?