K&N Drop In Filter... 2 MPG LOSS????

I have a brand new Tacoma TRD Sport. 6 speed. I drive 90 miles a day to work and home. 80 miles of the trip is Interstate. I set the cruise at 75 most of the time. I do NOT let the truck run/idle for any length of time mre than a couple minutes during the day.

At 800 miles I was getting 15.7-15.9 mpg out of the truck. So I put the K&N in. I ran 2 tanks of gas through the truck since. The gas milage has dropped to 13.5-13.7.

WTF? I thought a K&N was supposed to increase gas milage???

Anyone ever have this experience before? I put the stock filter back in yesterday and I plan to leave it in for a while. Maybe try the K&N again this summer.

 

K&N Filters are a mixed lot...sometimes they help, other times...

The only real way to tell is with a dyno!

Howard

 

I am just after gas milage, no desire to have it on a dyno.

I just don't understand how an air filter would be so harmful to the milage.

 

I got the same truck as your, because the engine not brake in, and weather relate, driving habit, heavy moisture in the air, my first 2 tank got average 300 milles, but now it got 340 miles even with mod. the 6 speed is not fuel efficency like auto trany .

 

first thing that popped in my head when i saw the thread. . . "hey man listen to this, sounds like a turbo winding up when i mat it!" hahaha

 

I have always been told the bigger the engine the more difference it would make. With that said, I had a Hemi Ram and put one in it. Couldn't tell a difference one way or the other. I did like it for the clean and reuse part though.

 

The dirt loading changes flow on the K&N, such that tuning doesn't hold...an you also have to remember that the engine is tuned to the stock airfilter and box.

There are EXTENSIVE discussions in the BMW Airhead world on K&N filters...also, I have decades of experience on tuning carbs

 

Did you disconnect the battery for 30 minutes after the install, give the computer time to re-adjust to more airflow.

 

Never disconnected the battery. Its just a drop in replacement filter. I have never had to do that on any other car I have owned including my Infiniti's. So I never thought it would be necessary to do that with a truck.

It's not a matter of me looking for more HP. I really don't care about that. I just wanted the convience of not having to ever buy a new air filter. And I had hopes of increasing my MPG.

I am just stumped that I lost 2 mpg by switching to a K&N.

 

I have the K&N drop in and didn't notice a difference either way. I have an automatic, so not sure if that makes a difference.

 

Never had a drop in, but I always resetted my ecu by disconnecting the battery and stepping on the gas pedal a few times while disconnected when I installed a short ram or cold air intake.

*** Try a Negative disconnect OP and see if it makes a difference or atleast gets you back to OEM MPG...

 

Couple of things that I would try, not necessarily in your preferred order:

o put the stock filter back in and see if the mpg's go back to normal
o replace with an AFE Pro-Dry drop-in
o clean the MAF sensor, K&N might have been over-oiled from the factory
o reset the ECU (disconnect battery) - I agree that a drop-in should not have a significant enough difference to require it, but what do you have to lose, besides your radio and clock settings

 

I was about to mention. The maf, if I'm not mistaken, is a wire uses heat dissipation to divine air flow. an insulator on it will corrupt its data.

THe original intake is pretty free flowing, but the truck might be touchy, and I haven't heard of anyone that tunes these things.

 

just a tip man, the 6 speed screams at 75mph running like 2800 RPM's drop her down to 70mph and I noticed a 3 mpg improvement consistently. trust me the 5 mph difference aint gonna kill ya, may add max 5 min to your commute.

also K&N air filters are the most over rated thing made since flowmaster.

 

there's already a spreadsheet someone figured out the MPGs at different speeds. 50 was best I think.. and mpg wend down dramatically after 55.