Someone is running around at the moment with the EGR blanked off - the car runs but it's drinking fuel. Also I have no idea what this would do to the DPF over a longer period
Not sure why it would increase fuel consumption. Maybe its another, totally unrelated problem why his car is drinking fuel. Plenty of people have blanked off the EGR on 1.9 and 2.4 engines in the 156/147/GT range without reporting increased fuel consumption and nothing has fundamentally changed in the designs of the engines.. Incidentally, at idle and full throttle the EGR system is closed anyway, its only part-throttle cruising rpm when the EGR valve opens to allow some smog to be re-burned.
The EGR is there to reduce Nox in the emissions, as Pud says, a combination of soot and oil mist fecks them up.
If replacement becomes continual, you may be leaking oil from the turbo bearing.
I'm not quite sure why blanking one would result in increased fuel consumption, but I'm out the loop these days.
My intake was always very oily on my 2.4 JTD, but it never used enough oil between changes (6-7k) for me to notice it on the dipstick. And I was very anal about checking the oil level, if it had dropped as much as 100 or 200ml I think I would have noticed..
That being said, I don't think it actually takes much volume of oil to leak to form the mist required to create that tar. There could also be oil mist from the crankcase breather.
It is possible to remove the EGR valve and blank it off.... But emmissions will be all out of whack for the MOT. My brother in law had the same problem with his 2003 2.4jtd 156 10v.
We removed it, cut a blanking plate to shape and sealed it with hylomar.
The EGR was then soaked (electrical contact sealed up of course) in brake cleaner for 24 hrs and then a good air blast to remove any further crud left.
Presto, one cleaned EGR valve on the shelf ready to fit a week before the MOT is due! It gives the car a chance to re-learn the emmision settings again.
NoX isn't tested at MOT time. Only CO, HC and Lambda is tested, non of which are affected by EGR valve operation provided the engine is running as it should.