Pannonian Posted October 23, 2011 Share Posted October 23, 2011 There is this extra filter inside the airbox I removed and then put back in, I don't really notice much difference having it in or out. It was glued in. I searched the forums, nobody mentioned it what it does or is it really necessary to have it in? Link to comment Share on other sites More sharing options...
Hanger Posted October 23, 2011 Share Posted October 23, 2011 yep, the GT does not have that extra air filter. Since it's glued in and nothing you can do about it so people just don't mention it i guess ○ ○ ○ Instagram: itshangertime :spin: ○ ○ ○ Link to comment Share on other sites More sharing options...
underground000 Posted October 23, 2011 Share Posted October 23, 2011 there was a post about this before its like an after filter/pre filter 5eat downshift rev match:) Powder coated wheels: completed:) Link to comment Share on other sites More sharing options...
Pannonian Posted October 23, 2011 Author Share Posted October 23, 2011 Ok, here is what I got on the BMW forums: http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/66688-charcoal-filter-removal-step-step-w-pictures.html According to this, the charcoal element is only there to catch any escaping hydrocarbons while the car is off and it's the California clear emmisions thingie so to hell with it.. http://www.m5board.com/vbulletin/attachments/e60-m5-e61-m5-touring-discussion/14494d1139084319-charcoal-filter-removal-step-step-w-pictures-m5-carbon-air-filters.jpg Only North American cars have this, and only certain makes and models I guess.. Link to comment Share on other sites More sharing options...
underground000 Posted October 23, 2011 Share Posted October 23, 2011 i was able to smell some gas when i had an engine bay cai, so that does make sense 5eat downshift rev match:) Powder coated wheels: completed:) Link to comment Share on other sites More sharing options...
MAx96 Posted October 24, 2011 Share Posted October 24, 2011 Snapped this thing off with a screwdriver two weeks ago. Immediately noticed more pep on the low end. Finally got the correct answer as to why it was there in the first place. Thanks. Link to comment Share on other sites More sharing options...
underground000 Posted October 24, 2011 Share Posted October 24, 2011 Snapped this thing off with a screwdriver two weeks ago. Immediately noticed more pep on the low end. Finally got the correct answer as to why it was there in the first place. Thanks. less restriction means more air flow which means more power, well thats what K&N says anyways 5eat downshift rev match:) Powder coated wheels: completed:) Link to comment Share on other sites More sharing options...
tito_b0y Posted October 24, 2011 Share Posted October 24, 2011 Snapped this thing off with a screwdriver two weeks ago. Immediately noticed more pep on the low end. Finally got the correct answer as to why it was there in the first place. Thanks. You get any CELs or other dash lights going off since then? 2006 SWP 3.0R 5EAT VDC BBQ 2008 OBP 2.5i 4EAT BBQ [RIP] Link to comment Share on other sites More sharing options...
MAx96 Posted October 24, 2011 Share Posted October 24, 2011 You get any CELs or other dash lights going off since then? Nope.. not a thing. Link to comment Share on other sites More sharing options...
apexi Posted October 24, 2011 Share Posted October 24, 2011 It was a lifesaver in my dads old car, so I'd never remove it from my car. A mouse chewed through the air filter in his old 4 runner so there was a big hole that could let all sorts of debris through, thankfully his car had that secondary filter too. While this may be a fairly rare incident, i like the idea of having a backup filter just in case the airbox is not closed properly or anything like that. Especially since I have a NA motor, I doubt I would see much performance increase from removing it. Link to comment Share on other sites More sharing options...
soloz2 Posted October 26, 2011 Share Posted October 26, 2011 Ok, here is what I got on the BMW forums: http://www.m5board.com/vbulletin/e60-m5-e61-m5-touring-discussion/66688-charcoal-filter-removal-step-step-w-pictures.html According to this, the charcoal element is only there to catch any escaping hydrocarbons while the car is off and it's the California clear emmisions thingie so to hell with it.. http://www.m5board.com/vbulletin/attachments/e60-m5-e61-m5-touring-discussion/14494d1139084319-charcoal-filter-removal-step-step-w-pictures-m5-carbon-air-filters.jpg Only North American cars have this, and only certain makes and models I guess.. Thanks! First good answer I've seen today. Current: 16 Crosstrek Premium w/ Eyesight & 05 Outback XT 5MT Past Subies: 14 FXT Premium, 14 WRX hatch, 06 Legacy 2.5i SE 5MT, 98 Outback wagon Link to comment Share on other sites More sharing options...
Pannonian Posted October 27, 2011 Author Share Posted October 27, 2011 It was a lifesaver in my dads old car, so I'd never remove it from my car. A mouse chewed through the air filter in his old 4 runner so there was a big hole that could let all sorts of debris through, thankfully his car had that secondary filter too. While this may be a fairly rare incident, i like the idea of having a backup filter just in case the airbox is not closed properly or anything like that. Especially since I have a NA motor, I doubt I would see much performance increase from removing it. But checking the air filter is easier on a Subaru Legacy, than checking the oil. Pop the the 2 snap clips up and you can lift it out to see if it has to be replaced. I do it at least once a month. But there is a slight increase in performance, I started to notice just now a few weeks later. I guess the ECU just learned the difference and compensated for it, it gets more airflow, and again..only in North America this thing is required, due to an overcomplicated law in California. Link to comment Share on other sites More sharing options...
bmx045 Posted November 2, 2011 Share Posted November 2, 2011 I'm glad everyone is comparing the M6's charcoal prefilter to the legacy's mesh screen, which is not a charcoal filter. The M6's is a completely different filtering system, the legacy's have a screen to catch large debris before it gets stuck in the slats of the filter. You can remove it, it won't change much, maybe an extremely small increase in airflow, but if you already have it on the stock filter, just go get a replacement filter as they don't even come with one. Autozone's STP filters work great. Link to comment Share on other sites More sharing options...
soloz2 Posted November 2, 2011 Share Posted November 2, 2011 I'm glad everyone is comparing the M6's charcoal prefilter to the legacy's mesh screen, which is not a charcoal filter. The M6's is a completely different filtering system, the legacy's have a screen to catch large debris before it gets stuck in the slats of the filter. You can remove it, it won't change much, maybe an extremely small increase in airflow, but if you already have it on the stock filter, just go get a replacement filter as they don't even come with one. Autozone's STP filters work great. Completely different than what this thread is about. We are not discussing a screen... Current: 16 Crosstrek Premium w/ Eyesight & 05 Outback XT 5MT Past Subies: 14 FXT Premium, 14 WRX hatch, 06 Legacy 2.5i SE 5MT, 98 Outback wagon Link to comment Share on other sites More sharing options...
soloz2 Posted November 2, 2011 Share Posted November 2, 2011 Just removed mine. I could smell fumes for a couple seconds after removing the filter. For those who have removed it... Mine had a couple little rubber spacers on a couple sides. Without those I'm wondering if my filter won't fit as snugly. Anyone move the spacers to the housing? Current: 16 Crosstrek Premium w/ Eyesight & 05 Outback XT 5MT Past Subies: 14 FXT Premium, 14 WRX hatch, 06 Legacy 2.5i SE 5MT, 98 Outback wagon Link to comment Share on other sites More sharing options...
bmx045 Posted November 2, 2011 Share Posted November 2, 2011 The picture shows the stock filter with the glued pre-filter screen on it..... it's nothing special, my 09 2.5i SE didn't have a screen at all.... Link to comment Share on other sites More sharing options...
soloz2 Posted November 3, 2011 Share Posted November 3, 2011 The picture shows the stock filter with the glued pre-filter screen on it..... it's nothing special, my 09 2.5i SE didn't have a screen at all.... That is not a pic of a standard air filter. That is a pic of an additional filter that is not normally removable on some Legacys. Two separate filters. Current: 16 Crosstrek Premium w/ Eyesight & 05 Outback XT 5MT Past Subies: 14 FXT Premium, 14 WRX hatch, 06 Legacy 2.5i SE 5MT, 98 Outback wagon Link to comment Share on other sites More sharing options...
MAx96 Posted November 3, 2011 Share Posted November 3, 2011 For those who have removed it... Mine had a couple little rubber spacers on a couple sides. Without those I'm wondering if my filter won't fit as snugly. Anyone move the spacers to the housing? Good observation, thought the same thing. No clue if it makes a difference or not, but I am going to cutout the charcoal mesh and put the frame for it back in. Peace of mind... Link to comment Share on other sites More sharing options...
soloz2 Posted November 3, 2011 Share Posted November 3, 2011 Let me know how that goes. My frame cracked in one place during removal. My car felt a lot more responsive yesterday. I only drove around town so under 35, but I could still tell a difference. Current: 16 Crosstrek Premium w/ Eyesight & 05 Outback XT 5MT Past Subies: 14 FXT Premium, 14 WRX hatch, 06 Legacy 2.5i SE 5MT, 98 Outback wagon Link to comment Share on other sites More sharing options...
Pannonian Posted November 3, 2011 Author Share Posted November 3, 2011 It's not an air filter that's for sure and I tried to search for it to buy another, but I don't see it anywhere. By the way if anyone scared taking it out you can always glue it back in. Since not every car come with it, not even the same exact models I really doubt this really screwing up anything. Link to comment Share on other sites More sharing options...
MAx96 Posted November 5, 2011 Share Posted November 5, 2011 Let me know how that goes. My frame cracked in one place during removal. Cut it out and threw frame back in, no difference whatsoever. Closely examined the charcoal filter, its definitely restrictive. Glad its outta there... Link to comment Share on other sites More sharing options...
road race legacy Posted January 22, 2013 Share Posted January 22, 2013 Sorry to bump an old thread. Just wondering if the guys that have removed this second air filter have any updates. Link to comment Share on other sites More sharing options...
sanchitosonria Posted January 22, 2013 Share Posted January 22, 2013 I have never heard of this until today... Link to comment Share on other sites More sharing options...
Richard_Mtl Posted January 22, 2013 Share Posted January 22, 2013 it's the cabin filter. http://www.flex-innovations.com/cabin_filter.htm Link to comment Share on other sites More sharing options...
apexi Posted January 23, 2013 Share Posted January 23, 2013 Pannonian is right, subaru calls it a "HC adsorption filter", to prevent emissions from exiting through the air intake after the car has been shut off. My PZEV non-turbo legacy has one. More info on hydrocarbon filters http://www.dacie.ca/pdfs/Mann%20&%20Hummel%20Filters/Brochures/Hydrocarbon%20Trap.pdf Link to comment Share on other sites More sharing options...
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