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Discussion Starter #1
So, maybe I'm just an idiot but I couldn't see a clear way to remove the charcoal filter in the air box without cutting it out with a knife? I've looked up some videos but the it seemed like they were screwed in, I checked in my impreza today and it looked like they had some stamped(?) melted plastic holding it in at the edges, is there a non destructive way to remove this?

Thanks for any help you can provide!
 

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I've never done it .. but there are instructions in the owner's manual. Looks like it should just pull out with no tools required. If you're still stuck I can go try it on mine.


Edit: dur. I see. I missed the point!
 

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Discussion Starter #4
I've never done it .. but there are instructions in the owner's manual. Looks like it should just pull out with no tools required. If you're still stuck I can go try it on mine.
The regular air filter comes out just fine, the charcoal filter is what I'm having a problem with. I think I'll leave it for right now until my break in miles are over, then I guess I'll just cut it out or something.
 

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I burned the loose strands of fiber to be sure nothing gets sucked into the engine.
 

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Su Baru - Did you notice any difference after removal? I see some other posts elsewhere that say it magically solves the sluggishness at about 2 -3k rpm.
 

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Su Baru - Did you notice any difference after removal? I see some other posts elsewhere that say it magically solves the sluggishness at about 2 -3k rpm.
It won't magically solve anything but everyone's looking for a way to increase the performance. Problem is that you can't based on the design of this engine. If you want to do it then do it but any increases "felt" will all be in your head:wink2:
 

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Su Baru - Did you notice any difference after removal? I see some other posts elsewhere that say it magically solves the sluggishness at about 2 -3k rpm.
I think throttle response is a little quicker, but not much of a change.
 

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Taking out any filter put in by an engine designer to protect the engine is just looking for problems down the road in my opinion.
I've have had a charcoal canister that the "wonderful" designers put on an engine in the 80's cause issues. I'll pass on charcoal in the intake system.
 

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Nope. What's the point of a charcoal filter in the intake? All you need is a basic media filter to remove dust and debris.

I'm assuming it's an activated charcoal filter. That's generally used to absorb volatile (highly evaporative) substances from water or air, like chlorine from water, or bad smells from the fridge.

I'm happy to be wrong. Maybe there's some other use for charcoal in a filter?
 

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This is why that little filter is there

"In a conventional vehicle, unburned gas fumes can escape through the engine’s air intake once the engine is shut off. To prevent this, Subaru PZEVs are equipped with a charcoal canister in the air intake that absorbs these evaporative hydrocarbon emissions."

Under "Dual-filtration air-intake system"
https://www.subaru.ca/WebPage.aspx?WebSiteID=282&WebPageID=17567
 

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How often should it be replaced then...?
I don't believe there is a replacement interval. It's not actually filtering any particles, so it's not like it can get clogged up over time. Some might argue that it could trap any particles that get by the engine air filter, and clog up that way.. But it's really not something I'd worry about.

Here's a little more information on the topic as well.

http://www.dacie.ca/pdfs/Mann & Hummel Filters/Brochures/Hydrocarbon Trap.pdf
 

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In my opinion, they have these just to pass some emissions standards test and never had any intention of saving the environment. Charcoal loses it's filtering effectiveness as contaminants and organics pass through it. I'll be very shocked and surprised if they have any impact beyond a year. So I guess what I'm saying is that there is no reason to keep it much less replace it.
 

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I removed mine gently and went for a drive. over 1 tank of fuel I didnt notice any difference and i decided to put it back as I run an oiled air filter. I had cut around the melted plastic welds holding the filter in and to re install i just placed the filter back and glue gunned over the melted plastic welds.
 

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My 2018 didn't have any PZEV badging or any mention of it in the sticker.
Do I have one of these in my car, or is it PZEV specific?
Asking because I'm lazy.
 
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