BMW E90 320i DIY Washing Air Filter "Sleeve"

I suspect nothing was done to my air filter during my 1st BSRI service last week at the SC. At 24k km I figured the OEM air filter is pretty clogged up because if its K&N, it would be pretty dirty at 20k km. Since our air filter element is covered/protected by a synthetic wool sleeve, it's washing time! :D

Refer here for instruction to open the AF box:
http://upgr8s.blogspot.com/2008/03/bmw-e90-diy-opening-air-filter-box.html

"Prying" open the air filter box after removing the several T-20 screws:


Separated the sleeve from the element:


Dip the sleeve into a bucket of water premix with dish cleaning detergent:


Moving the sleeve in and out of the soap water repeatedly for several minutes and this is what u get:

After cleaning, it dries pretty fast because the synthetic wool repels water:


Slot it back to the filter element and kao tim!


Now, expecting my all time FC meter to drop from 11.5L/100km to below 11 region.. :p :D

A new discovery while doing this DIY:

I got this Air Filter buffer box removed by unscrewing T-15 screws marked with the red cross in the photo.


Flipping it over I noticed the interesting rips and air tunnel EXCEPT the huge green question mark:


Check out the inlet in this close up:



When in position, pay attention to the right inlet:



You see what I see? :eek: