new intake, poor mileage

[mtboard]

I just installed a 57 series K&n intake on my 05 6.0 F250. I have the standard 6" lift w/ 35's. Before installing the intake I was averaging 12 or 13 mpg. Now i am getting 8 or 9 MPG. The mileage drop happened as soon as the intake was installed. Has anybody else had this happen or any suggestions as to what else it could be? I have 27000 on the odometer. I dont think the fuel filters have ever been changed, dont know for sure. If the fuel/water seperator was full would that cause a drop in mileage? obviously I am new to oil burners so any help would be great.
Thanks

[WEWILLE]

Did you hook everything up properly? Doublr check to be sure.

You must replace the filters, both fuel filters. You can ruin injectors in a heartbeat with low fuel pressure.

Yes water in fuel will affect mileage. Personally id ditch the aftermaket intake, cause your stock intake can handle 500 or so horsepower...

[Lubbockguy1979]

i have seen lots of stuff on here pro and con about the k&n i have seen the display as well that make you think they are better because the ball thing floats like it is open. i have read testimonials of how the k&n increases horsepower by straitening the air over no air filter etc. my exp with them is as follows. i had 2 or 3 on different pickups and they didnt seem to do anything more than make the exaust a little louder. i personally think that with a turbo that will be potentiall sucking 2x the air i would rather have more media for it to suck thru. the stock fiter is more effective at trapping dirt than a aftermarket end of story. i work in the hvac and plumbing area and i personally prefer a paper media that has better filtration to a washable media. i have to clean a lot of indoor units that people dont take care of and the pleated media seems to work the best when changed properly. i have seen ford techs comment on more than one occasion that people with aftermarket filter kits (drop in and full intakes) have had noticable amouts of dirt past the intake that is not the same as others with stock filters. this leads me to think that they are less effective than the aftermarket. given the potential of 5-20hp and the general consensus of the boards against the filter systems i think that the potential increase in horsepower vs taking the chance of ruining a 1000 to 2000 dollar turbo to be a no brainer. the k&n filter is a oiled filter and is also not the best filter to use. technology has improved since that inception and dry filters work better as well

[caissiel]

Ford is using the most advanced filter media, and its the most efficient for removing dirt, and a lot of dirt it can remove. I used a K & N in my 6.5L because I had only 8Lbs Max and also in my naturally aspired 6.2L GM. I did Notice much better result in My 6.2L and realy got a lot of added torque. But in My Ford the Turbo pressure is to the Max at every time I put a load on it so I feel I never will need anymore Pressure. My Hypertech realy make the turbo increase the boost to make my truck kick butt. Of course I have my right hand and left foot to control my shifting, and not so conserned about Trans control.