i know they confuse MAF's due to the oil sticking to them, but is it only oiled Airfilters that cause problems or is there some design issue that causes all induction type filters to cause running issues.

secondly if you get opne do you need to get the car remapped (my04)?

thanks in advance

 

AFAIK, it is heavily oiled filters that cause most of the problems. That said, any air filter, poorly fitted wouldn't be good for the MAF!