WTF...2nd Air Filter in Airbox, 2007x3????

[ace996]

So I open the airfilter to see what can be done for an airfilter/airbox/CAI and I find that there is a second filter in the airbox...one that looks like an aquarium filter...even with charcoal in it!!!!!

I was very tempted to just pull the stock filter and leave the 2nd filter there...but I pulled out the rotary tool and cut out the filter and about half of the mounting plate/bracket.

Anyone else see this 2nd filter...??? Any idea why we'd have a filter with charcoal in it?
I've never seen this before...

Be good,
TomK

[JCL]

I don't know about the 2007 X3, but I do know that there are secondary charcoal filters on other BMW models (particularly the M5, where I first read about it, but likely other models as well). They are only on the US models. The filter is there for emissions controls. It is designed to prevent fuel fumes from escaping from the engine/intake tract when the engine is shut off. Removing the filter simply increases your emissions in that circumstance. The filter has no effect when the engine is running, whether to reduce emissions or performance. I can't see any benefit in removing it, the restriction is negligible. You will likely not fail any local/state emissions tests having removed it because they are unlikely to test that aspect, but at least in some parts of the world, if you are found to have defeated emissions controls you can be required to replace them.

It is not advisable to remove the stock air filter, and leave only the charcoal filter as it does not filter particles as the regular filter does. Also, there are reports of potential damage to the engine from ingesting carbon particles if the carbon filter is cut or damaged. Be very careful and ensure that no particles from your modification have ended up in the intake tract.

[pm127]

I see a lot of people have viewed, but no one has tossed out an answer. I'm under the impression that activated carbon filters are used largely to remove odours. Many typical water filters are made of the same thing.

If anyone wants to elaborate, fire away.

P.

[JCL]

Originally Posted by pm127

I see a lot of people have viewed, but no one has tossed out an answer. I'm under the impression that activated carbon filters are used largely to remove odours. Many typical water filters are made of the same thing.

If anyone wants to elaborate, fire away.

P.

I did The charcoal filter removes fuel fumes that are in the intake tract after the engine is shut down. California emission law that has spread to the rest of the country.

Lots of discussion on e90post.com, and on various M5 forums. One of them points out that the replacement filter costs $450 for an E90 on RealOEM, as it is bonded into the filter housing. I don't think the dealer would see it at end of lease, but if they did I think the owner would be liable for returning the car to stock.

Didn't like my answer in post #2?

[ace996]

JCL,
I never thought about using charcoal for fuel fumes in the intake....
It's common practice to use the charcoal canisters for emissions for the fuel tank vent, but the intake is a new one for me....and for emissions??? That's insane and a little overboard, as I've never heard of anyone complain that their car smelled a little too much after they parked it...
And someone probably was paid a pretty penny for coming up with that joke...clowns.

I cut it out with a rotary tool, sanded it down so nothing's left and cut the plate in half, so as to not mess with the designed airflow into the intake horn.


Be good,
TomK