Secondary Air Filter?

[stevec5000]

In my 2004 V6 'Runner I noticed that behind the normal removeable airfilter in the black plastic manifold housing there is also another filter that is fixed in place. Mine looked pretty dirty and was probably blocking most of the air. I had to cut 6 plastic pins to remove it from the manifold but I don't know how to clean it or if I should put it back in though. Does anyone know what that's for and if it's really needed?

 

[Atlanta_man]

there's lots of info on here
search for hydrocarbon filter

leave it off, be happy

 

[stevec5000]

there's lots of info on here
search for hydrocarbon filter
leave it off, be happy

OK found it. I didn't know it was called a hydrocarbon filter. I don't see any difference in mileage or performance but it probably would make a difference in acceleration since it looks like it would block a lot of airflow.