Hi all, the A4 has started to smoke like its got 200 bensons on the go at once. Does not seem to loose any power and is fine driving but when it pulls up at lights etc its smoking like crazy, white blue smoke not dirty black and smells a a bit oily. Strange thing is it doesnt do it all the time, most of the time its fine with little or no smoke?EGR valve sticking perhaps, what do you think?