need more info what age is car, as completely different diesel engines pre and post march 2010. ie early one is a psa engine the later in bmw own n47 diesel,
some things that are same with both are below
dpf filter partially blocked needs a good 20 miles run at 3000 revs on motorway best place to do it. this should hopefully get dpf to clean its self out by regen,
need to scan car see if have any fault codes logged if you have this will clog dpf filter as wont will not regen,
when was fuel filter changed last. ie bets practice is 10-15k
the later n47 diesels suffer timing chain stretch any signs of rattle from gearbox side of engine is bad needs looking at will end badly. egr valves are set to the cars ecu with replacing them so needs software to work correctly, have found after market egr valves to be hit and miss some just dont play nice,
its possible to map out the egr valves and dpf filter and turn it in to a reliable car again but is a mot failure if does not pass the visual check, i know a garage that does them correctly can tell its not there and go's through the gas check on mot lower than before, ie the check all cars are like this, its a drop in the morning go sight seeing for the day and pick car up at end of day all done, they also do custom maps for eco or power driving, i got a insignia sports tourer 2,0 diesel that will leave wheel spin 1 2 3 gears in dry but still will do over 60mpg driven carefully, the bmw n47 reacts well to mapping no lag just good strong power form 1000 revs all way to top, these guys are based on the devon cornwall border, just ask for john at black magic ecu remapping specialist ltd 01579 388980
this might not be where you want to go with it but anyone else who see the good in it and it really is like driving a new car after its all done,
