What is the purpose of the charcoal filter in the filter box?
I know it filters incoming air, but why?
The only application I have seen on a car was to purify the air from the gas tank (vapor system) (Saab 9000) ? But why charcoal filter intake air? As far as I understand (please correct if I am wrong) charcoal filters out chemicals not dust (air filter does it already) so why is it there?
What atmospheres was Toyota expeting us to drive the vehicle in? Sulphur? Propane? CO?

Anybody? Also, what would be the implications of removing charcoal filter other than improving intake air flow....

Thanks,

 

I think the charcoal filter is in the cabin filter, not the airbox...

-THE DON

 

It's actually not a filter at all. The charcoal accepts and releases hydrocarbons readily. When you turn off the engine and some intake valves are open and some unburned fuel remains in the cylinder, it migrates out the open intake. These are emissions and are measured when the car is certified. The charcoal absorbs the unburned hydrocarbons and holds them till you restart the engine and then they are pulled back into the engine to be burned. It works, it was neccesary, it does not hurt performance and removing it will provide no gains.

 

Scott,

Thanks so much for detailed info. That makes sense although I've never heard of charcoal component releasing any substance it absorbed, I thought it was a one way process, (what abot gas masks????)

If that is not going to harm anything I will remove it IMHO any obstruction in the air intake path is BAD (people spend $$$ to improve air flow)

Thanks again,

Stefan

PS. DONE. I also dynoed the car right away and verify an 0.9HP gain...

 

I hope you work at a shop because that would be a huge waste of money to dyno that. Also, dyno ratings vary alot depending on temperature and humidity and whatnot.

 

too bad dyno's have something like a 3-5hp error margin