K&N Filter

mavsman26 · 12-24-2011, 01:40 AM

Guys,

Just replaced my air filter (e90 330i) at 58k miles. I went with a K&N filter instead of stock.

I've noticed much lower gas mileage (albeit only after 2 days of driving). Any suggestions?

Was considering taking off the assembly and checking the fit again. Has anyone had a similar issue?

cdgatti · 12-24-2011, 07:26 AM

K&N filters or any freer flowing filter seem to elicit changes in gas mileage. Some reporting higher some lower. I would wait till your ecu fully adapts to make a conclusion. I could see that before your ecu adapts, since your intake may be introducing more air at a the same throttle position, it would mix in more fuel.

mavsman26 · 12-24-2011, 12:38 PM

I see, will wait it out and see if the system adapts.

Thanks!

queensfield · 12-24-2011, 02:12 PM

Make sure MAF sensor wasn't messed up during the filter change and is in fact clean. You can try cleaning it carefully if mileage does not improve over time. It's a sensitive and expensive part. Regular MAF cleaner from auto stores works fine. Make sure it is completely dry before putting it back together.

Hooy · 12-24-2011, 02:16 PM

Clean your MAF. The kit comes over oiled out of the box.

DJ Apex · 12-24-2011, 05:45 PM

Yep i was about to say the same thing clean your MAF.

monza2t · 12-24-2011, 06:37 PM

Also, people tend to drive a little more agressively after a 'mod' because they feel better about their car. MPG goes down accordingly...

DJ Apex · 12-24-2011, 06:53 PM

Quote:

Originally Posted by monza2t

Also, people tend to drive a little more agressively after a 'mod' because they feel better about their car. MPG goes down accordingly...

Heard that

mavsman26 · 12-31-2011, 12:06 AM

mileage still not improving and no change in driving habits. will try to clean the sensor as suggested. thanks!

Route 16 · 12-31-2011, 12:50 AM

Note: I drive grandma style 65mph cruise highways but I do have spirited driving moments, less than 20miles?

I got my first BMW 5 months ago and stock/charcoal filter/stock air box/stock exhaust, I got good mileage 420-430miles per tank.

1 month later gruppe-m rep intake with k&n cone filter, eisenmann full exhaust, 400-410 miles per tank.

Last week put back stock air box/k&n flat/charcoal filter, eisenmann full exhaust. The first tank about 6 days 400miles. 2nd tank 420-430miles per tank, if not more because I haven't finished it yet.

I do agree that the ECU has to adapt and takes a bit of time. I kept the charcoal cuz the k&n is too oily so I'm making the charcoal soak that up before it gets to the MAF.

Pros: better mileage
Cons: exhaust is a little quieter

I'm not to crazy about hearing the intake or HP gains, just want good miles and loud exhaust.

Ateam · 12-31-2011, 02:00 AM

Sorry bud but its absolutely pointless to use a KN or free flow filter with the charcoal filter

No matter how free the filter is, the point of restriction is the charcoal so its providing no benefit at all.

I am 99 percent sure the OP needs to clean the MAF. I used to clean mine with every oil change around 12k miles (my car no longer has a MAF to clean which is nice!). This should take care of the problem for you.

I have found KN's are over oiled more than most other brands. BMC is the best IMO and I never had an issue with oil getting on the maf with the bmc filters.

12-24-2011, 01:40 AM	#1
mavsman26 New Member 1 Rep 17 Posts Drives: 2006 330i (Euro Delivery) Join Date: May 2006 Location: SF Bay Area iTrader: (0)	K&N Filter - Lower gas mileage? Guys, Just replaced my air filter (e90 330i) at 58k miles. I went with a K&N filter instead of stock. I've noticed much lower gas mileage (albeit only after 2 days of driving). Any suggestions? Was considering taking off the assembly and checking the fit again. Has anyone had a similar issue?
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12-24-2011, 07:26 AM	#2
cdgatti Colonel 255 Rep 2,547 Posts Drives: e90 328i Join Date: May 2011 Location: KY iTrader: (4)	K&N filters or any freer flowing filter seem to elicit changes in gas mileage. Some reporting higher some lower. I would wait till your ecu fully adapts to make a conclusion. I could see that before your ecu adapts, since your intake may be introducing more air at a the same throttle position, it would mix in more fuel.
	Appreciate 0 Quote

12-24-2011, 12:38 PM	#3
mavsman26 New Member 1 Rep 17 Posts Drives: 2006 330i (Euro Delivery) Join Date: May 2006 Location: SF Bay Area iTrader: (0)	I see, will wait it out and see if the system adapts. Thanks!
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12-24-2011, 02:12 PM	#4
queensfield First Lieutenant 21 Rep 364 Posts Drives: 2006 330i E90 Join Date: Aug 2011 Location: So Cal iTrader: (0)	Make sure MAF sensor wasn't messed up during the filter change and is in fact clean. You can try cleaning it carefully if mileage does not improve over time. It's a sensitive and expensive part. Regular MAF cleaner from auto stores works fine. Make sure it is completely dry before putting it back together.
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12-24-2011, 02:16 PM	#5
Hooy Colonel 205 Rep 2,770 Posts Drives: E92 328i, E92 M3 Join Date: Sep 2009 Location: Houston, TX iTrader: (12) Garage List 2008 E92 328 [5.00]	Clean your MAF. The kit comes over oiled out of the box. __________________
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12-24-2011, 05:45 PM	#6
DJ Apex Lieutenant 25 Rep 473 Posts Drives: 2006 330i Join Date: Nov 2010 Location: Houston TX iTrader: (1)	Yep i was about to say the same thing clean your MAF.
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12-24-2011, 06:37 PM	#7
monza2t Private First Class 3 Rep 160 Posts Drives: E90 328i, R52 Mini, F25 X3 x35 Join Date: Dec 2011 Location: Kansas City iTrader: (0)	Also, people tend to drive a little more agressively after a 'mod' because they feel better about their car. MPG goes down accordingly...
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12-31-2011, 12:06 AM	#9
mavsman26 New Member 1 Rep 17 Posts Drives: 2006 330i (Euro Delivery) Join Date: May 2006 Location: SF Bay Area iTrader: (0)	mileage still not improving and no change in driving habits. will try to clean the sensor as suggested. thanks!
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12-31-2011, 12:50 AM	#10
Route 16 I got lei'd 846 Rep 7,594 Posts Drives: '10 E90 M3 Join Date: Sep 2011 Location: Dark Side of the Moon iTrader: (62)	Note: I drive grandma style 65mph cruise highways but I do have spirited driving moments, less than 20miles? I got my first BMW 5 months ago and stock/charcoal filter/stock air box/stock exhaust, I got good mileage 420-430miles per tank. 1 month later gruppe-m rep intake with k&n cone filter, eisenmann full exhaust, 400-410 miles per tank. Last week put back stock air box/k&n flat/charcoal filter, eisenmann full exhaust. The first tank about 6 days 400miles. 2nd tank 420-430miles per tank, if not more because I haven't finished it yet. I do agree that the ECU has to adapt and takes a bit of time. I kept the charcoal cuz the k&n is too oily so I'm making the charcoal soak that up before it gets to the MAF. Pros: better mileage Cons: exhaust is a little quieter I'm not to crazy about hearing the intake or HP gains, just want good miles and loud exhaust.
	Appreciate 0 Quote

12-31-2011, 02:00 AM	#11
Ateam Banned 88 Rep 1,105 Posts Drives: M3 Join Date: Sep 2011 Location: USA iTrader: (0)	Sorry bud but its absolutely pointless to use a KN or free flow filter with the charcoal filter No matter how free the filter is, the point of restriction is the charcoal so its providing no benefit at all. I am 99 percent sure the OP needs to clean the MAF. I used to clean mine with every oil change around 12k miles (my car no longer has a MAF to clean which is nice!). This should take care of the problem for you. I have found KN's are over oiled more than most other brands. BMC is the best IMO and I never had an issue with oil getting on the maf with the bmc filters.
	Appreciate 0 Quote