First, open the door.

Attached Images

 

Open the hood

Attached Images

 

And pull the yellow handle to open the hood

Attached Images

 

release the clip on both side of the intake chamber as indicated

Attached Images

 

Use a small flat head screw driver to release intake sensor from the intake box
and loosen the clamp screw on the flexible tubing

Attached Images

  

Loosen the bolts with 10mm socket

Attached Images

 

pull out the air box and loosen all 5 screws with a T-25 Torx screwdriver.

Attached Images

 

Open the air box.
Cut the carbon filter.
The result is like this.

Attached Images

  

Use sandpaper to smooth the surface on the cut area

Attached Images

 

Take a break. Repeat as many times as needed

Attached Images

 

Carefully clean the air box. You don’t want any particle sucked into the engine. And assemble the air box.

Attached Images

  

Reverse the step 1-6 and you are done.

Attached Images

 

Post removal:

I found the engine runs smoother and revs faster. The hesitation between 1500 to 3000rpm is greatly reduced to none. The engine sounds a bit more clear and (just a bit) louder under heavy acceleration.

is that k&n air filter?

if so should i go pick one up before doing this
?

It's up tp you. You can stay with stock filter. I use K&N because it is easier to clean and save money in the long run.

hey does this void the warrenty or anything?

If you happen to have an issue that relates to the air flow I could see BMW stating that the air filter setup had been modified in a way not approved by them. Not sure but it's a possibility. I think euro BMW's may not use these filters (at least the E60 M5).

Thank you very very much.

You have to clean it based on where you live. If you live in a dusty area you will have to clean it more. Maybe inspect every 7-10k. The oil solution used to trap particles can and will get dirty so clean or inspect every now and then. Your filter should look pink and if it is no longer pink, then you need to go and get a recharge kit from any auto store and clean it. Just make sure not to over spray the final solution or you can damage the MAP sensor. People have this problem all the time so be careful.

After doing this DIY, I have added an observation. Once you cut the filter out there is a very rough syrface, and it's COVERED in black charcaol dust.

I removed the MAF sensor from the airbox.( Just two #20 tork screws) BE CAREFUL with this part, it's fragile!! Then I used a dremel to smooth all the rough edges. Sandpaper will work too, but a dremel is faster.

Whether using sandaper or dremel it will create a TON of dust. I then washed the entire airbox, and let it dry completely. (this is why I removed the MAF sensor)

It's an easy mod, and the combination of adding a K&N filter, plus this mod, added a very noticeable improvement in throttle response, trust me. As for HP, probably not much, but it's still worth doing since down the road having that stupid charcoal filter in there will definitely cause airflow restriction since it's not replaceable!! It's almost like having two air filters, a poor design IMO. But, I guess a few states (CA for example) were concerned with vapors escaping into their precious atmosphere when the vehicle is turned off!? We have greater air concerns, believe me! OK, off my soap-box.

Thanks for DIY....very detailed and straight forward!!!