issues in the rain

delvec03 · 12-09-2022, 11:40 AM

2015 228i 6MT n20 FBO DV+ CDV delete K&N air filter.

For the longest time I've had some rumbling with a little extra roar at about 2500 rpm in the heavy rain. I'm fairly confident this has always been there, before the tune and bolt ons, stock, since I picked up the car from the dealer.
The other (after 4 hours in the rain) day I had a first- while pulling away from a light the rumbling shifted to stumbling into drivetrain malfunction. Silly me didn't pull codes....car off/on issues cleared.

The day after (1.5 hrs in the rain) after the drive home I did some pulls and had significant loss of power in 3rd and 4th gear at about 3000 rpm. No check engine.

Since then, weather has been dry and car rock solid. My thought is that the car isn't handling the humidity well. Any issues out there with n20s in rain? K&N air filter in the rain?

Thanks for any comments!

freakystyly · 12-09-2022, 11:46 AM

Best way to test that theory would be to swap in a paper filter before your next downpour. I think it is possible since some cars trip MAF sensor errors depending on which airbox/filter combo they use.

Another thing, since I mentioned it, get some MAF cleaner and spray your sensor down. Maybe the K&N fouled it up a bit with oil.

12-09-2022, 11:40 AM	#1
delvec03 First Lieutenant 90 Rep 351 Posts Drives: 228i Sport/ DSB Join Date: Feb 2015 Location: United States, DC iTrader: (0)	issues in the rain 2015 228i 6MT n20 FBO DV+ CDV delete K&N air filter. For the longest time I've had some rumbling with a little extra roar at about 2500 rpm in the heavy rain. I'm fairly confident this has always been there, before the tune and bolt ons, stock, since I picked up the car from the dealer. The other (after 4 hours in the rain) day I had a first- while pulling away from a light the rumbling shifted to stumbling into drivetrain malfunction. Silly me didn't pull codes....car off/on issues cleared. The day after (1.5 hrs in the rain) after the drive home I did some pulls and had significant loss of power in 3rd and 4th gear at about 3000 rpm. No check engine. Since then, weather has been dry and car rock solid. My thought is that the car isn't handling the humidity well. Any issues out there with n20s in rain? K&N air filter in the rain? Thanks for any comments!
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12-09-2022, 11:46 AM	#2
freakystyly Lieutenant Colonel 3008 Rep 1,798 Posts Drives: F22 B58 6MT Join Date: May 2016 Location: Ontario iTrader: (0)	Best way to test that theory would be to swap in a paper filter before your next downpour. I think it is possible since some cars trip MAF sensor errors depending on which airbox/filter combo they use. Another thing, since I mentioned it, get some MAF cleaner and spray your sensor down. Maybe the K&N fouled it up a bit with oil.
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