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Should I dump my K&N air filter?

5K views 45 replies 22 participants last post by  Alex323Ci 
#1 ·
The original owner of the 330i I bought last year put a K&N air filter on it. It needs a cleaning and oiling which makes me nervous because I've heard the oil can get on the MAF sensor and cause problems. And I've heard that not using enough oil can cause more dirt to get past it.

I'm going to the junkyard this weekend. Should I get an airbox and reinstall the stock air filter system?

My car has low miles and I'm probably going to keep it for a long time. And I'm not worried about spending $20 or so once a year for an new paper filter.
 
#3 · (Edited)
+1 on stock airbox if you can find one at the junkyard.

I had a K&N in my 330i for a while and eventually went back to stock because it wasn't worth it. The K&N sounded a little better and looked cool under the hood I guess but it will let more particulate through the filter than stock even when newly cleaned/oiled.

https://nicoclub.com/archives/kn-vs-oem-filter.html has a bunch of graphs showing just how little is actually filtered with a K&N. Pair that with the fact that you gain somewhere between 0 and 4 HP, maybe, and I personally don't think it's worth it to go aftermarket.
 
#6 ·
It's funny how some think that putting hot air through the intake improves performance. The stock airbus pulls from the front of the car through the grills which is cooler than the recirculated air like the K&N. I've noticed watching the show Wheeler Dealer that Ant grimaces when he sees them, notably on the recent Porsche 996 and Mazda RX7 episodes.
 
#9 ·
Guys love jerking their possessions off to make them superior to the guy next to them at the stop light who happens to be doing the same thing. The never-ending man-pursuit of incremental "upgrades" to make them faster, louder, or meaner than the next guy at the local strip-mall tuner gathering. We've all been guilty of it at some point or another but at varying levels and degrees.

Many don't have the actual skill or nuanced critical thinking required to actually make their car meaningfully and efficiently faster, so they do it the only way they think they know how: their credit cards and a screwdriver. They haven't done the research. The aftermarket tuner industry knows this and takes full advantage with bogus misleading marketing.

The E46 specifically is already a highly optimized vehicle right out of the box.
 
#13 ·
I too had a MAF issue after I installed a KN air filter. I would get a lean code shortly after installation. Cleaned MAF, cleared the code but after several hundred miles, it would reappear. Did this for like 3-4 times. Finally, my MAF gave up and no matter how I cleaned it, the code would reappear a day later. Bought a new MAF from FCPeuro and threw the KN filter in the garbage. Happy ever since.
 
#14 ·
i’m not sure if the design you have is good or not. if it has a shield you probably have a good kit. not a lot of power but initial throttle and top end. but mostly sound.
don’t think there has been one case of ruining the MAF sensor. it’s almost always user error and vacuum leak.

people without knowledge are always afraid of things they don’t know. gauze filter media seems to be one of these. K&N is used by the factory on the Shelby Cobras, used by the US military on Apache helicopters in the desert and Dinan used them on their super chargers. Even the M3 CSL uses a gauze filter panel.

if you have a bad design that is allowing heatsoak then it's a bad design for street. that’s for track.
 
#16 ·
i’m not sure if the design you have is good or not. if it has a shield you probably have a good kit. not a lot of power but initial throttle and top end. but mostly sound.
don’t think there has been one case of ruining the MAF sensor. it’s almost always user error and vacuum leak.

people without knowledge are always afraid of things they don’t know. gauze filter media seems to be one of these. K&N is used by the factory on the Shelby Cobras, used by the US military on Apache helicopters in the desert and Dinan used them on their super chargers. Even the M3 CSL uses a gauze filter panel.

if you have a bad design that is allowing heatsoak then it's a bad design for street. that’s for track.
Just my opinion but here's what I think about that statement -
Brembo makes brakes for some high end cars and they are quite well, but brembo also makes brakes for our cars. Are they the same? Absolutely not. The brakes for higher-end cars are more performance oriented versus the ones for our cars.
I feel like that same situation could be applied to OE and OEM. Sure, Denso makes a lot of things for Lexus and they are great but that doesn't mean their parts for our cars are going to be the same
 
#15 ·
Thing is though, people here don't drive Cobras or apache helicopters. Most E46s owners are driving around 3,300 lb mass produced street cars that make under 250 hp on its best day. the bro mentality of "yo im driving a STR8 UP ATTACK WEAPON DAWG WATCH ME FIGHT UR CAR" is what spawns misconceptions of what their credit card can do. My friend drove an actual F1 car in barcelona and elsewhere a couple times and he says he doesn't even think of his Z06 as a sports car anymore. Says it makes it feel like a slow top heavy POS. Some in their E46s are dreaming when they think they're driving around fast sporty cars.

A lot of the problem with these "upgrades" is peoples perceptions of what they drive. It's way over here -------------------------------------> When it should realistically be waaaaay over here on the spectrum of slow to fast <-----------------------------------.

Your cars and all our cars are 3,300 lb heavy steel objects w/ airbags, leather, plastic panels, thick insulating glass, sound insulation, 100 lb seats, padding etc. An air filter isn't going to earn you your racing stripes. The only change you'll perceive is sound

That being said, drop in replacement filters are the lesser of the sin of spending $400 on an entire intake system on a $5,000 car. But I've helped all kinds of people where their K&N or equivalent was causing more harm than good. It's best to leave highly designed, highly calibrated systems as is. You start to unnecessarily jerk it off, and you introduce unnecessary potentials into the mix.

BTW for you KN/GAUZE FILTER BROS, check out this study: http://www.gmtruckcentral.com/articles/air-filter-study.html

Still wanna roll those red filters?

 
#19 ·
Most E46s owners are driving around 3,300 lb mass produced street cars that make under 250 hp on its best day. the bro mentality of "yo im driving a STR8 UP ATTACK WEAPON DAWG WATCH ME FIGHT UR CAR" is what spawns misconceptions of what their credit card can do. My friend drove an actual F1 car in barcelona and elsewhere a couple times and he says he doesn't even think of his Z06 as a sports car anymore. Says it makes it feel like a slow top heavy POS. Some in their E46s are dreaming when they think they're driving around fast sporty cars.
there you have it, drive a F1 car or just drive a Prius like Mango. :rofl:

there’s no modification that should be done :confused:
 
#17 ·
Should I dump my K&N air filter?
Yup. They don't filter nearly as fine a particle as stock paper do.

In my personal experience. On cars.
Especially on an E46 that had had a Dinan cone stuck down into the fenderwell.
I had to clean the thick layer of GRIT outa the inside of the
cardon faiber tube just to see it was really cardon faiber.

t
stock filter in a stock airbox on a stock car.
 
#18 ·
Should I dump my K&N air filter?
Yup. They don't filter nearly as fine a particle as stock paper do.

In my personal experience. On cars.
Especially on an E46 that had had a Dinan cone stuck down into the fenderwell.
I had to clean the thick layer of GRIT outa the inside of the
cardon faiber tube just to see it was really cardon faiber.

t
stock filter in a stock airbox on a stock car.
 
#29 ·
If I had to go with an aftermarket filter, I'd probably go BMC, if for no other reason than a having Euro bias (and the CSL uses a BMC filter, so apparently BMW thinks their media is effective enough). That said, a stock paper filter flows more than enough for a non-M. Same as the E46 M3 non-CSL filter (well except the E46 M3 doesn't have the pre-filter part), which means that filter flows well enough for at least 343hp.
 
#36 ·
I have a Dinan filter and modified airbox because it was on my car when I bought it. It***8217;s a nice, shiny piece of kit. I***8217;m 99% sure, behind the wheel, I***8217;ll never notice the difference between that and stock.

I did notice that a new filter cost $50 though ...
 
#39 ·
You've convinced me to put a stock air filter back on. But there was none to be found at the junkyard even though they had at least three or four e46s and there's nothing being parted on right now out Craigslist. So it looks like I'll be cleaning the K&N and keeping it for a little while.
 
#40 ·
It took me months to find one at the yards- oddly, they seem to be in demand.

You will also find that there are several changes in sizes for both intake and
AFM, and that the size you need will be the one that's never in the yards.

Do make sure to get the 325 or 330 box- the 328 box has a smaller inlet.

hth

t
 
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