performance air filter
 

I added a K&N high performance factory type air filter to my 1992 jeep wrangler last week. I was amazed. It dropped my mpg from 17.00 to 11.6mpg. I went back to the cheap standard air filter and today rechecked my milege. 17.25 mpg. This was enlightening. I got more horsepower and it ran more open with the K&N but at a cost. I'm guessing the oxygen sensor saw more oxy and thought it was lean....added more gas!!!!

Most likely you were using the little extra power and that caused your mileage drop. Happens all the time. I've got a K&N filter and while i didn't notice a performance or mileage increase it's reusable which reduces my waste.

noper
 

No way!!! I drive like an old man. Shift at 2k, turn off engine at red lights, coast in neutral. The filter killed my mpg.. Period! I got the mpg back as soon as I changed it.

the filter was probably over-oiled and the excess got into the air-metering system gumming it up. certainly wouldn't be the first person to have that happen... or the 100th... or the 1000th

been using K&N filters on my honda civic and my wife's Toyota Sienna for the past three years. K&N allows for more air flow, and the more airflow the more power but since your engine is getting more air flow it will use more gas to maintain the AF ratio.

you will get more hp but burn more gas in the process. in the past the increase in power is good even if my vehicles burn more gas since gas was cheaper. now a days though the increase in hp is not worth the extra fuel my vehicles are burning. since I am hypermiling and don't use the full power potential of my vehicles anyway, I can make do without the extra hp that the K&N filter adds.

I am thinking about just changing to a regular paper filter and compare the difference in mpg. I am thinking that boosting your ignition system would actually be better than boosting your engine's airflow. a better ignition spark will provide a cleaner fuel burn with the same AF ratio and will deliver better mpg.

I have replaced my civic's sparkplugs with Halo sparkplugs, MPG+ sparkplug wires, and an Accel Supercoil ignition coil. The halo sparkplugs have been in the engine for two weeks and it has been delivering a good FE increase but my full tank of gas only went from 300 miles to around 330 to 340 miles. the MPG + wires actually boosted my mpgs a lot more and before I installed the Accel Supercoil I was getting 350 to 360 miles per tank of gas (that's 10 gallons). I've installed the Accel Supercoil just a couple of days ago and the car has better acceleration AND at only a quarter tank spent I have already gotten 130 miles (that's about 2 gallons or a little over 2 gallons, mostly high way miles though). I can't really get an accurate mpg rating since I don't have a Scangauge yet so I rely on the total miles per full tank.

it is weird that my civic registers more miles for the first half tank than the second half tank. so taking the mpg calculation by the fuel gauge is totally inaccurate for me. I guess my fuel gauge is no longer accurate (probably came from topping off the tank to the max ever since I first bought the car).

I am eagerly anticipating what my total miles would be after this current tank of gas and see what type of gains I've gotten from the combination of the Halo sparkplugs (www.greenplugs.com), MPG+ Sparkplug wires (https://www.increasing-gas-mileage.co...roduct_Code=6c), and the Accel Supercoil which delivers an extra 10 to 15% power to the spark plugs than OE ignition coils.

after this current tank of gas, I will replace the K&N filter with a paper filter and see if the reduction of air flow to the intakes will boost mpgs better.

I think this only matters at high RPM when you're moving a lot of air. I suspect that there's no useful difference between the flow at the low RPMs that hypermilers use.

It's quite normal, actually. My brand new VW, which I never top off, does it. Every GM and Ford I've ever driven does it. The only reason I can think of for it is so that they can sell more cars when people say "My behemothmobile gets 200 miles to half a tank with aggressive driving".

I think you're right. so for hypermilers, there's really no advantage to the much more expensive K&N filter.


LOL! that sounds right!

Yeah I got 150 miles on the first quarter of my 15 gallon tank at the moment, that's 40MPG!!!!!11111

LOL! now that's FE!

nah think about it this way: lets take a 20 gal fish tank. perfectly rectangular cut it in half (ie 1/2 a tank) and the shapes and thier volume capacities will be exctly the same.

take a car fuel tank that can look liek a trapezoid, pancake, square top round bottom, etc and im sure most of em when cut horizontally in half do not hold equal volumes (hence one half burns "quicker" than the other half)


i put a K&N alogn with a CAI on my s-10. i noticed a 1-2 mpg gain over the stock maze. most of it was prolly the CAI itself and not the filter (cone filter)

ive had it on for 2 years now so i might swap back to stock and see what it gets then.
it didnt really help performace wise (mayeb high rpm's alogn with the high flow exahust it does) but the normal driving rpm range didnt do anything