[r33_RGSport]

Simple mod that I've done today.

While RaceChip is doing a test with my car, I play around with the airbox since it need to be removed to access couple of the sensors.

So, here are the steps from the very beginning.
Note: I don't have the first few steps pictures.

Step 1:
- Remove the side plastic cowl by turning the clip 90º and covers that held down by plastic rivets.
- Remove the strut tower bars, held by 2x 13mm nuts on each side.

Step 2: (You can skip this step if you want to work on it on the car)
- Use flat screwdriver to loosen the clamp for the air hoses.
- Pull out the hoses from the engine cover/air box. It held down by rubber grommets, so just pull upward.

Step 3:
- Use TORX 25 to undo 8 screws holding the cover.


There will be 4 filters. 2x long and 2x short.


Step 4:
- Use flat screwdriver or your finger to press the locking tab to slide up the air filter bracket fastener. 2 fastener on each side per air filter.




- Then pull off the air filter bracket to remove the paper air filter to expose the Charcoal filter.


Step 5:
- Use a pick or small screwdriver to pry off the charcoal filter. It held by 2 tabs on each side. 1 top and 1 bottom on each side. But, you will get them off easily once 1 or 2 tabs already popped loose.




Do that on all 4 filters, and put it back together. Then you all set.

How much horsepower gain? I would say 40hp.

Honest answer, I don't know. Because I have the RaceChip installed right after and it is still in testing stage.
RaceChip doesn't sell something that is still in testing stage.
So, it will be another thread once it is finalized and have before and after dyno on it.

Have fun and enjoy this small DIY!!!

[onfireX5]

It clearly is molded onto the Charcoal Filters " DO NOT REMOVE"....just like a mattress tag....LOL....

They look smaller than the air filters.

[POM3]

Is there any filter already for sale? I remember I did remove the charcoal from my F80 but also installed a Afe dry filter. It is a lot of work just to remove the charcoal. I was hoping Afe or BMC would have something available by now to make it worth the work.

[r33_RGSport]

Originally Posted by POM3

Is there any filter already for sale? I remember I did remove the charcoal from my F80 but also installed a Afe dry filter. It is a lot of work just to remove the charcoal. I was hoping Afe or BMC would have something available by now to make it worth the work.

Not yet.
IMO, if the stock filter is good enough for 500hp, it would be as good as BMC or AFE Dry Filter.

[M5 TT]

normally UK cars don have them. Will need to go find out anyway

[spta97]

I would have assumed these are for the in cabin air. Is that not the case?

Thanks for the DIY - we need more in this forum!

[2kaccordocoupe]

Originally Posted by spta97

I would have assumed these are for the in cabin air. Is that not the case?

Thanks for the DIY - we need more in this forum!

These have nothing to do with cabin air. The fresh cabin air / HVAC has it's own set of filters completely different from these.

The charcoal filters on the engine air intake are for emission controls and emission certifications.

When you shut off the car for example you have some unburned fuel in the cylinder, these vapors can travel back up the intake and leak into the atmosphere. The charcoal filter traps and holds these vapors so they don't escape out to the atmosphere to comply with stricter emissions requirements.

[2kaccordocoupe]

r33_RGSport

Thanks for this Ben, wow that is a bit of work to get them out LOL.

Notice any changes in sound after removing them? I remember when I did this on my F82 the turbo spool sound were somewhat more audible.

[spta97]

Originally Posted by 2kaccordocoupe

These have nothing to do with cabin air. The fresh cabin air / HVAC has it's own set of filters completely different from these.

The charcoal filters on the engine air intake are for emission controls and emission certifications.

When you shut off the car for example you have some unburned fuel in the cylinder, these vapors can travel back up the intake and leak into the atmosphere. The charcoal filter traps and holds these vapors so they don't escape out to the atmosphere to comply with stricter emissions requirements.

Thanks for the info - I was not aware of that.

[r33_RGSport]

Originally Posted by 2kaccordocoupe

r33_RGSport

Thanks for this Ben, wow that is a bit of work to get them out LOL.

Notice any changes in sound after removing them? I remember when I did this on my F82 the turbo spool sound were somewhat more audible.

No sound improvement. The airbox is well insulated.

I managed to find a shortcut for removing the tower bar.
You don't need to remove the whole side covering, just remove the 2 plastic rivet holding each side cover on top of the tower bar.
Then lift it enough where you can access the 13mm nuts.

Just be careful when you put it back.
Make sure you clear the EDC cable before tightening. I pinched mine, good thing it didn't break it.

[2kaccordocoupe]

Originally Posted by r33_RGSport

No sound improvement. The airbox is well insulated.

I managed to find a shortcut for removing the tower bar.
You don't need to remove the whole side covering, just remove the 2 plastic rivet holding each side cover on top of the tower bar.
Then lift it enough where you can access the 13mm nuts.

Just be careful when you put it back.
Make sure you clear the EDC cable before tightening. I pinched mine, good thing it didn't break it.

[StockX4M]

No change in sound for the turbo spool?

[Kozumasbullitt]

Any follow up on this?

[Sarg33]

Here is my post from another thread on this...

Yesterday I was looking to see if anyone had removed the charcoal filters from the intake. I was looking for more of a how-to. I like to remove them because in my opinion anything that adds restriction to the intake is not a good thing. I removed them on my M2C as well. I found an old post on how-to from r33_RGSport. The process was painless even though I think the filters are held in place with category 5 hurricane rated devices. Over engineering at its best!

Immediately went on over 200 mile drive of mixed freeway and city traffic. Can't say as I heard any difference in engine noise, but I swear the throttle response improved. It seems to rev quicker and smoother in the lower RPM. Perhaps a placebo effect, but I am pleased with it and it was free. I am charcoal free now. Shout out to r33_RGSport for the great how-to post!!!
Side note, I drive in Sport / D2 and averaged 22.0 MPG.

[Kevin_The_Clean1]

This is a great idea. But I think I'm going to simply stick with my Eventuri high-flow filters and call it a day. The charcoal units seem pretty high flowing / unrestrictive units that are just there in place to filter outgasing from the engine while it's turned off for new emission standards.