To keep any raw fuel vapors from escaping out through the intake, when turning the car off.

 

Thank you, Billybob! Makes sense I guess - not really a concern to me as much as drivability.


For certain the extent of the secondary filter fastened into the lid of the air cleaner compartment is really restrictive. Such a difference noticed once that is removed and, of course, a free flowing air filter installed.

 

No proven benefit with K&N but may damage engine

Unless the "cool" sound of the K&N is worth burning up an engine, real world Independent tests show these things don't increase gas mileage or power.

Go here to my post #4 (my favorite part being in the real world video that shows when they removed the air filter on the test vehicle for zero restriction, there was no change in horsepower):

http://www.toyotanation.com/forum/1...ration-2002-2006-2007-2011/473713-2007-camry-se-k-n-intake-new-tail-lights.html

And here to the gen3 Avalon forum, paying special attention to post #4 :

http://www.toyotanation.com/forum/1...rum/156-3rd-generation-2005-2012/423212-anyone-modified-their-stock-airbox.html

 

Oh, the humanity!
You could be killing us all.
The pollution!


Quick, call the EPA. Call Volks wagon. Call Bernie!


In jest.


For reality, in the end, I would expect that with all of the computers that regulate the air fuel mix, that the K&N air filter won't help, either way.


The Charcoal filter looks a little restrictive, but what is the purpose/reason for the K&N/?

 

Thanks to all who responded. Regarding the purpose of the low restriction air filter (for me) is personal preference. This new vehicle is the 35th I've owned over more years than I care to admit. I began using the filters about 20 years ago - have been using them on all the vehicles since - with great satisfaction.


Removing the lid filter in the Avalons have (in my opinion) greatly improved drivability.