K&N filter question

[Highboy]

I've seen many posts about K&N filters oiling up MAF sensors. Just changed my air filter on my Highlander and has some sort of carbon filter fastened to the top of the air filter box. My Scions have the same. I read on some Toyota forums it had something to do with emissions. So my question is how is oil from the K&N filter getting on the MAF sensor if it has to go through that carbon filter in the top of the air filter box? Maybe other car brands don't have this carbon filter.

 

[kschachn]

OK, I've never seen that before, apparently it is to trap back-flowing fuel vapors instead of releasing them to the air.

If the K&N is allowing oil to get through, would you want that then to be trapped on this carbon filter? It seems like over time it would foul up the carbon element, which would require replacement of the housing.

In regards to a K&N in general, what is it that you are trying to achieve?

Originally Posted By: Highboy
I've seen many posts about K&N filters oiling up MAF sensors. Just changed my air filter on my Highlander and has some sort of carbon filter fastened to the top of the air filter box. My Scions have the same. I read on some Toyota forums it had something to do with emissions. So my question is how is oil from the K&N filter getting on the MAF sensor if it has to go through that carbon filter in the top of the air filter box? Maybe other car brands don't have this carbon filter.

 

[Highboy]

It is permanent. It is mounted to the top of the air box. It still uses a paper filter. Just wondering how so many have reported getting oil on the MAF with the carbon filter there. And is there a chance this carbon filter can be blocked with oil?

 

[CT8]

Why would any one want a K@N filter?

 

[OneEyeJack]

Originally Posted By: CT8
Why would any one want a K@N filter?


Dune buggy or dirt bike.

 

[Warstud]

Originally Posted By: OneEyeJack
Originally Posted By: CT8
Why would any one want a K@N filter?


Dune buggy or dirt bike.

You especially dont want to use one in a dirty environement

 

[Wolf359]

I think the major problem with K&N is that when people re-oil them, they put too much oil in it and then it ends up coating the MAF. If you've got something blocking it, then it might not be a major concern. However there's no real point to the K&N these days. i don't think the extra cost and risks are worth any performance gain.

 

[Rolla07]

Zero difference in performance. I switched back to a plain paper element filter. People likely over coat their K&N's with too much oil. If you use right amount of oil it should not coat the MAF. If cold air intakes dont add HP than these filters certainly wont.

 

[CT8]

Originally Posted By: OneEyeJack
Originally Posted By: CT8
Why would any one want a K@N filter?


Dune buggy or dirt bike.
Back in the 70s I tried one on a M/C and the carbs got dirty real quick. I speak from experience not regurgitating what I read on a subject I know nothing about or able to discern if it is the truth or just marketing.

 

[901Memphis]

Your average K&N is only 96% efficient (worse if cleaned/oiled wrong) while a good paper filter is 99.5%+...a lot of silicon going into your bearings with the K&N, the MAF is moot when you consider the dirt issue

 

[circuitsmith]

That second carbon filter captures any raw fuel vapors left when the engine is turned off.
Removing it won't affect engine operation and will reduce restriction a tiny amount.

 

[Skanky]

Dirt passes through way to much for me, intakes were always dirty.

 

[Greasymechtech]

Many pop off that carbon filter simple to reduce flow restriction. Then, add in the KN, which too many overload with oil.

 

[Pontual]

MAF gets hot and abundantly ventilated, Im sure it will evaporate the fluid thin oil without leaving any residues, even if a little overoiled.