Air intake Filter,Foam or No Foam

[madwolff]

The Air filter in my 2002 325I has foam on the bottom.

Does the car need the foam or will a filter with out the foam be better?

[ezbmr]

How about you just get a k & N, then you can just wash it every oil change or so

[rchan11]

Do not get foam! Foam will fall to pieces with age and get suck in to the MAF. I'm talking from experience.

[Rob24857]

+1 K&N
-1 Foam

[pizzaman09]

I have read that K&N filters mess with the MAF. Several e38 guys have had a lot of trouble with K&N filters on their M62 engines.

[miniz119]

The Foam on the bottom of the OE filter is used for very very dusty areas ... if you live in an area that tends to have a lot of dust and fine particles in the air, then its perferred !!! The K&N filters do mess with the MAF (if you over-oil the filter) ... other than that clean the MAF once in a while with some MAF sensor cleaner !

[frostlane]

The Foam on the bottom of the OE filter is used for very very dusty areas ... if you live in an area that tends to have a lot of dust and fine particles in the air, then its perferred !!! The K&N filters do mess with the MAF (if you over-oil the filter) ... other than that clean the MAF once in a while with some MAF sensor cleaner !

You most likely won't have a problem with a K&N filter. Whenever you re-oil it make sure not to use too much. Also after you do re-oil it drive it around for a day or so, pop the filter off and clean the maf sensor.

[ECSTuning]

The Air filter in my 2002 325I has foam on the bottom.

Does the car need the foam or will a filter with out the foam be better?

As mentioned above, foam might not be the best idea. K&N are great filters.

However if you are concerned about potential oil in your maf you might consider the aFe Dry S Drop In Filter.

Pro Dry S filters feature a synthetic oil free material, allowing increased airflow.

Constructed with 100% polyurethane on all four sides, this high flow “oil-free” OE replacement performance filter will outflow stock paper filter for improved horsepower and torque.

Two layers of progressively finer mesh synthetic media provide maximum convenience and easy maintenance.

Washable and reusable for multiple cleaning cycles, the tall open evenly spaced pleats provide excellent dust holding capacity for longer service cycle between cleanings.

Integrated urethane bump seal insures tight, no leak seal over the life of the filter.

Click HERE for more information.


Please let us know if you have any questions! Feel free to shoot me a PM or email.

Best,
Joe

[Tangent]

We have such little horsepower to gain through the intake that the only reason to go with anything other than OE is the convenience of a washable one. The OE filters that have the extra layer of foam don't come apart the way some all-foam filters apparently do so don't worry about that.

[STEALTHYZ4]

If the foam filter is changed before it becomes dry-rotted,due to heat,age, there will be no problem...use OEM!

[Dubbedown]

I have read that K&N filters mess with the MAF. Several e38 guys have had a lot of trouble with K&N filters on their M62 engines.

That's not e38 specific but will happn with any make/model when you OVER oil the filter.

[Tangent]

That's not e38 specific but will happn with any make/model when you OVER oil the filter.

Also when you believe all the hype. K&N has a pretty good series of video responses to the hysteria: http://www.knfilters.com/MAF/massair.htm

[sunbrn]

We have such little horsepower to gain through the intake that the only reason to go with anything other than OE is the convenience of a washable one.

Nothing more convenient than throwing it in the trash in installing another oem filter.

[sprintman]

The question I ask, as do many, of Krap & Nasty users "ever read a UOA from an engine using one"? They never answer yes as they wouldn't own one if they did.

[pizzaman09]

That's not e38 specific but will happn with any make/model when you OVER oil the filter.

I see, so the over oiling messes with the MAF.

[Tangent]

Nothing more convenient than throwing it in the trash in installing another oem filter.

Unless the mood to do a bit of light maintenance strikes you one day and you don't have a new filter lying around. My wife's Saturn happened to have a K&N installed by the PO, my BMW gets OEM filters. It's much more convenient to pull out the bottles of cleaner and recharger I bought for her filter a couple of years ago than it is to order a new filter for mine. That's my preference anyway. Although for the price of a K&N I could just stock up on several OEM filters...

I see, so the over oiling messes with the MAF.

Seriously, watch these: http://www.knfilters.com/MAF/massair.htm

[g00dwagen]

Run the stock Mann filter in the yellow & green box. They work great.

Follow this link for all you ever wanted (or didn't) want to know about K&N air filters. It confirms what lots of us in the aftermarket repair, & off-road business have suspected for a long time. They let in a lot of gunk & then they clog up, fast.

http://www.dieselbombers.com/chevy-g...r-testing.html

No "Z0MG! It's diesel! Doesn't Count!!!", it's an excellent, out of pocket objective test by enthusiasts, that is eye opening.

[Tangent]

I've read that test before. One thing I really hate about it is that it uses absurd amounts of dust, it just isn't obvious when measured in grams. The Accumulated dirt capacity test for example shows that the K&N can "only" hold 211.6 grams of dirt. To put that in perspective, that's nearly half a pound. The dust loading test uses a constant flow of over one and a quarter pounds of dust per hour. What exactly are these tests the equivalent of, 5 years worth of driving down dirt roads without ever changing the filter?

EDIT: I'm overdue for a filter change anyway, I'll try to remember to weigh my used OEM filter and compare it to the new one to see just how much dust it's holding...

[g00dwagen]

I've read that test before. One thing I really hate about it is that it uses absurd amounts of dust, it just isn't obvious when measured in grams. The Accumulated dirt capacity test for example shows that the K&N can "only" hold 211.6 grams of dirt. To put that in perspective, that's nearly half a pound. The dust loading test uses a constant flow of over one and a quarter pounds of dust per hour. What exactly are these tests the equivalent of, 5 years worth of driving down dirt roads without ever changing the filter?

EDIT: I'm overdue for a filter change anyway, I'll try to remember to weigh my used OEM filter and compare it to the new one to see just how much dust it's holding...

FYI, the Duramax filter is gigantic, 8 ounces spread across one of them, in relative terms, is like 2 ounces on an E36 filter.

You're ignoring the most important conclusions of the test however, how much dirt passes through the filter & is ingested into the engine?

Glad to see you're using genuine filters!

[Tangent]

You're ignoring the most important conclusions of the test however, how much dirt passes through the filter & is ingested into the engine?

Not so much ignoring as wondering how the amounts passed through in the test relate to the real world. Considering that the test uses amounts that would probably still be very high vs driving through record dust storms for week, how much could we expect them to pass in actual day-to-day use? Those 2 ounces an E36 filter might pass in the test could be immeasurably tiny amounts in real life use...

[pizzaman09]

Seriously, watch these: http://www.knfilters.com/MAF/massair.htm

That was an interesting read. I wouldn't go out to spend money on a filter like that but is was interesting to know more how it works. I never knew that the K&N filters were life time filters, I just assumed they were cheap filters meant to add fake power to Hondas. Shows how much I know about them.

On another note I have been through 2 MAF sensors in the last 3 months and don't want to have to get another one.

[lkchris]

Another guy with a "do I really need it" question!

Auto makers don't put on stuff you don't need.

I mean, after all, the aftermarket is here to tell you what cheapskates they are.

[pj530i]

The filter I just took out of my car had an extra layer of stuff on it (it was felt-like, not foam), but the filter I put in didn't.

http://www.rmeuropean.com/Part-Numbe..._8DF8FDD7.aspx

That's the filter I got. Was the previous filter wrong, or does it just not matter that much?

[HardWorkandRest]

There's a bulletin out there where a code is set from installing the improper air filter in your E46. I don't know the engineering aspect exactly, but it creates a similair situation to a vaccuum leak, allowing too much air to get into the engine. Do as you please, but if you happen to aquire this issue, understand that it was owner provoked.

Bulletin 12 20 07 to be exact.

[Tangent]

EDIT: Found that bulletin. http://ww2.justanswer.com/uploads/2p...171504_tsb.pdf

SITUATION
The customer complains that the "Service Engine Soon" light is illuminated. The fault codes "2882/2883
– fuel trim, mixture too lean" are stored in the DME.
CAUSE
Possible causes may include: incorrect air filter, unmetered air or a defective air mass meter.
PROCEDURE
Remove and inspect the air filter element. Only the filter with the P/N 13 72 1 744 869 must be fitted. If
the filter is the correct one, please follow the test plan and repair accordingly.

I want to know how an incorrect air filter would cause this. The only thing I can think of is that it's overly restrictive or comes unseated somehow, but those are just guesses...