Drop in MPG after K&N Dropin?
 

I just installed my K&N drop-in filter and noticed my avg MPG drop from around 29 to 25. Has anyone else seen this happen, or would think it would?

I'll be making a 6 hour freeway drive soon for the holidays, so I'll be sure to check then (to hopefully cut out changes in driving style out of the equation).

I got an AFE filter and noticed the same thing. I went from 33 to 29, after a few tanks it went back up though.

yeah same thing happened to me, i went from 26mpg to 22.5 with k&n drop in but i do 99% city driving

Yes, please let us know the results.

humfrz

My MPG dropped as well. I was at 29-ish before I installed mine, and it dropped down to 27-ish. Installed my K&N filter like 2-3 months ago I think?

It makes perfectly logical sense though. Upgrading the filter reduces air restriction, which means the car is able to intake more air. More air = more fuel = more power = less mpg.

For me, I only lost roughly 2 mpg, which wasn't/isn't noticeable. I do mostly city driving, with a little bit of highway driving here and there. I have a 6MT, and I tend to redline my car occasionally once the engine is fully warmed up (185 degree oil temps minimum).

That's weird, I wouldn't think a high flow air filter would affect your mileage at all. I'd grab some MAF cleaner and give your MAF a few squirts. K&N's are usually significantly over oiled out of the box, you could have a dirty MAF because of this.

I put a intake on my miata and my Mazdaspeed3 and I actually gained mileage. About 2mpg in the miata and 4 in the speed3.

The speed3 was a full intake but the miata was just a k@n filter.

Also heard about resetting the ECU after installing new intakes. Would this be needed for a simple drop-in as well?

Doesn't hurt. Let's the ECU learn the increased flow the filter provides.

To reset the ECU you just unhook the battery for 60 seconds, is that right?

Sure it's not a heavier foot to feel more power or to try and hear the intake :P?

Ok how are all of you averaging this high of a number? Im lucky to average 22, but I do drive fairly aggressive and fast... a lot.

Set your red light rpm indicator at 4,000 rpm ..... and you to can get 30 mpg.....:D

humfrz