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 :)

I'm getting 11.3L/100km here but I do drive very spiritedly and live in a big city with VERY heavy traffic. Had a TRD air filter installed but not much difference in terms of fuel consumption.

I didn't notice any change between filters....

Temp swings and or the use age of the ac and your right foot have large impacts.

I'm usually around 28-30 calculated or 32 on the readout.

I have a Perrin drop-in and have noticed zero change in mpg. My dash readout has been pegged at 33.3 for the last few tanks, with the actual mpg being whatever is in my sig.

I run a K&N drop-in and Q300 catback. Mixed driving yields around 35mpg. 37 with heavier freeway driving.

http://i.imgur.com/pEXijEW.jpg

its all about driving habits. i was averaging ~30 mpgs before my exhaust went on. now its ~25...... lol

Ahhhhh! Don't tell me that! I'm at 30 mpg now and my catback is en route.

It's not that it will directly affect MPG, you'll just want to put your foot down more often. :P

What application is that?

I'm in the private beta for Automatic, found at Automatic.com. It's been great so far, but no support for really detailed info out of the OBD port. Definitely for general consumer use.

That app looks like it might call the police if you get freaky in the car on the road.

I don't think that's all true - must be other factors.
my catback didn't change a thing - I was getting 35-40 on the stock tires.
when I changed the tires/rims - then that will mess sht up bit time. just saying.

i was saying my mpgs went down because my foot was also going down. hard.

...lol

Only in the event of an accident. Things like spinning out, etc. are not reported. But if I plan on tracking or being a little crazy, I can always unplug the device from the OBD port temporarily and all is well.

Luckily I tend to not do anything stupid in the street.

I noticed drop of about 1 l/100 which is about I bekieve 2-3 mpg after I installed the drop in. Pretty sure I installed it right. Spent a fair amount of time for full seal and proper box alignment.

Have winter tires vs summer tires and longer trips of highway. Will spray maf cleaner and reset ecu in the summer. Will lyk.

On my 17 86 I have an k&n drop in and nitrogen in tires I run 93octane gas and live in the desert. Crushing on the highway at 72mph I average 44+mpg now in the cool months.

I have found that with these 3 things I increased 9-13mpg depending on temps and driving style. In town I average 25mpg.

Side note I have tested this on wrx, Imprezas, b9 tribeca, and s2ks and have seen increases across the board and no decrease.

What tire pressure?

And we care because....

35psi all around on 225 45/17

Holy necro bumping a 5 year old thread...

So that drop of 1 L/100 km was due to my winter tires because I put my summer back on and I'm getting around 7.7 L/100km average again which was when I have summer tires but not the K&N drop in filter..

IF there is any drop in mileage, it's negligible, maybe 0.3 L/100 km.

*At all times, I calculated mileage using the speed control at different speeds. Don't ask me what those numbers are, I deleted my stats by accident but I'm confident adding the K&N filter doesn't affect mileage much, if at all.

Wrong thread buddy. This is mileage with VS without K&N filter. That's the only factor that changes.

I wonder how many airboxes aren't sealed properly with "drop in" filters?