Poor Gas Mileage with K & N Air Filter

[Trem720]

So last week I had my oil changed and air filter checked, and was told I needed a new air filter. I decided to put a drop in K &N filter in rather than the OEM paper filter. I was told that by removing the HCF filter, I would gain a little more flow as well. So I went ahead and did this, and since then, my gas mileage (according to the onboard computer) has gone WAY down. I would consistently get 17-18 around town and 22-23 on the highway (with 32.8"tires and a 3" lift). Now the on-board comp is reading 12.5-12.9. No matter how aggressive I drove before that, I never saw my computer below 16.8. What do you guys recommend? Should I try resetting the ECU? I can't imagine how removing the HCF and adding a new K &N would cause this.

Thanks.

 

[Casper421]

First off, the onboard computer is very misleading; real mpg is usually 2-3 less than the computer says, probably more with bigger tires due to the calibration for 31" stock tires. Try this: fill up, reset your A or B odometer setting and once you refill write down the miles and gal's you refilled. take into account you have 32.8" tires compared to stock 31"s. Recalibrate the miles then divide that by the # of gal's you refilled and you have your mpg's.

The K&N filter is made to allow more air into the engine leading to more gas being used. That results in lower mpg's. Typically any aftermarket power-adder(intake, exhaust), whether or not it tells you it increases mpg's, decreases mpg's. Usually, if your engine sounds louder, your foot automatically gets heavier...i know, its crazy!! :shrug:

Either keep the K&N or replace it with OEM. Good luck! :cheers:

 

[chaz]

:iagree:

 

[SOMDRUNNER1]

If your driving habits have not changed, your mileage should not decrease! Mileage should remain the same or increase slightly as the engine breathes a little more freely. I have not installed my K+N on my 5th gen. yet, but I have installed cold air intakes (and cat-back exhausts) on my last three trucks and the mileage usually increased slightly.

 

[kai920]

I saw a very slight increase with a drop in K&N. No drop. But I kept my HCF