K&N Air Filter installed, MPG dropping?
 

As the title says, just put in a K&N Drop in filter and my MPGs are steadily dropping. Will it change after a few hundred miles? (ecu learning?) Something i forgot to do? thanks for any info.

Did you clog the sound creator tube while you were at it?

I ended up resetting my ECU after installing the filter by disconnecting the negative battery terminal for 10 minutes. Not technically necessary for something so minor, but my mpg after a full relearn was more favorable. Worth a try.

You sure its not just driving habits? My MPG has only gone up or stayed steady for the past several months. Mostly just consciously trying to drive economically and only pushing when I feel sporty. I've been averaging 25.4 mpg with about 80% city driving. My longer freeway trips see 33-35 mpg. I have a manual trans and put in a K&N drop in filter back in may.

Ive been averaging 9.8

@Young_makaveli MPG or L/100km?

I installed the K&N air filter last weekend, have gone through one full tank of gas. My MPG has increased by 1.3 mpg, from 25.57 mpg to 26.9 mpg. I did not reset the ECU, I just popped it in.

Sorry L/100km

Actually I'm getting

Attachment 50110

I wouldn't rely on the dash display, it's very.... optimistic. I track everything myself through the Android app FuelLog:

http://img541.imageshack.us/img541/6426/hh5b.png

clean your maf sensor.

What he said. Get a bottle of MAF spray cleaner.

I cleaned mine 50 miles after a K&N install just to be safe. Probably will do it again before I get a tune.

Fuelly is a great tool to use as well just like that app. Runs off your odometer or trip meter. My MPG gauge is usually 1.5-2 mpg off from the actual number mainly because it factors in idle time.

8.5 here , driving spirited every now and then, not even that much highway... I wonder how much it would drop if I were to put in an aftermarket drop in filter :)