i searched and didnt find much of anything about this. i have a hps elbow coming and a drop in k&n just wanted to get some opinions on this.

 

Leave it. Some say it can disrupt airflow past our very sensitive MAF sensor.

 

A few years ago, caymandriver did something like that and removed it. He dyno it with it off and it lost power. This was done on an is350.

 

An observation and a question. The charcoal filter in the IS F only covers the lower half of the air box. Every other Toyota/Lexus air box I have seen covers the entire opening. Why?

 

I yanked mine...no issues.

 

The charcoal filter functions to trap hydrocarbons which are back flowing from the intake of the engine when the engine is not running. Hydrocarbons are heavier than air so they flow along the lowest point of any channel. The charcoal filter sits at this low point so even being only half it still absorbs the back flowing hydrocarbons. Once you start the engine the airflow pulls the hydrocarbons from the charcoal filter and the engine ingests and burns them.

 

Sorry, poor writing on my part. I understand why/how it works… Just trying to stir up thoughts on on why Toyota would not do this for other cars.

 

The charcoal filter, full or half is based on how the air filter is arranged in the air box and I also think that Toyota was trying to give as much flow to the isF as they could and still pass hydrocarbons emission regulations. A lot of Toyotas have a horizontal filter, in this case they would need a full horizontal charcoal filter so that the low running stream of hydrocarbons would always run through the charcoal and not have a clear path around it.