2007 Fiesta 1.6tdci. Previously bought by me when 6 months old. Now owned by my brother. Has 164k miles on it. 

A few months ago EML came on , read codes and there are a few to do with EGR valve, which come back almost straight away when cleared.  Car sometimes drives fine but sometimes lacks power, but does run smoothly when driving and he's just carried on using it

Today we were giving the car a pre-MOT check over and we found that when revved in neutral it gets to about 4000rpm then coughs and splutters and as it coughs and splutters it has a load of white smoke. Engine temp was quite low first time so it was driven around and thrashed and warmed up but it was just the same.

Does anyone know if this can be caused by EGR valve problems or does this sound like something different.  

 

Was there any other codes? The EML came on on mine back when it had that leaking injector. The code said it was the EGR but that didn't come back after being cleared and most likely popped up as I was only driving it in and out the garage before getting insurance to drive on the road. 

I don't think the EGR can cause those symptoms. Does it run like that after it's warmed up? 

Only codes that came up were EGR codes. I can't recall what they were exactly, I wrote them down and gave the list to my brother (the car owner). It was just the same when warmed up.