Hello, I'm new in the forum and I was wondering if anyone know why my s40 start like with missing power, to be more specific about the problem, I have a s40 II t5 2008, after changing the mass air filter the car start like it would start when is hot, like if he lost power.

Thank you for your time

 

What brand filter did you use? Could it be too restrictive? Changing the filter should not cause an issue. Could you have done something else that may have knocked off a vacuum hose?
Stan

 

I cleaned the original one (I know I shouldn't do that but I have to prove it) and it seems that the problem was the filter, the engine is running "normal" now, the filter was a fram, thank you for your time

 

Best to use OEM paper filters. Volvo intakes are pretty well designed so there's no noticeable benefit to a KN filter or cold air intake etc. Similarly after market oil filters can be more restrictive than OEM and can result in lower than acceptable oil pressure.

 

I agree about the K&N filter. I saw no benefit in power or fuel economy. Based on oil analysis, they don't filter as well as a good paper filter. Bob the Oil Guy can always tell if you are running a K&N just by the particulate in the oil. That is not to say that the particulate is at harmful levels.