1999 E-150 5.4 L
I replaced the stock air filter with the recommended K & N model. My MPG dropped to approx 10 MPG.
The K & N is about 2/3's the size of the stock filter.
Any advice?

 

i just put my k&n in at lunch time today. I hope this doesnt happen to me. i am interested to see what type of responses you get. i have read mostly good things about switching the filters out. maybe it takes a while for the cars computer to learn the new air/fuel ratio. it might be a few miles before it adjusts the mixture.

just a guess.

 

Yes, go back to the OEM paper filter. There have been many reports on the amount of dirt that the K&N will pass into your
engine. If you look at the Cummins website, they are explicit in
stating DO NOT use a K&N air filter!!! You also risk contaminating
your MAF sensor, from the oil in the K&N.

The extremely, extremely, small, if any, performance increase is only due to the weight reduction in your wallet!!!

 

umm there is something wrong other than your airfilter.

Did you accidently unhook the MAF sensor?

is the CEL on?

Did the trip odometer accidently get bumped or something?

My personal experince with K+N has been nothing but good news, and that's over a span of 8 different vehicles.

 

Disconnect the battery and let the computer reset itself. Mine got better mileage after I did this.

 

I have a 97 f-150 with a 4.6l engine. I purchased a k&N for it about two years ago. I drove with it in for about a year and my gas milage was horrible. This filter cost me a $100 bucks and I saw no increase in power or fuel milage. I put a new stock filter back in and my milage was excellent. Definitly one of the worse investments I have made for my truck.

 

Hmmmmm,if the K&N filter is such a good thing for your truck then why doesn't Ford install them from the factory?

 

I've run the stock paper filter when I've got the K&N filter drying after a cleaning. On the same run from the house to the next town down the valley and back (about 90 kms), I don't record any difference in mileage. Performance gain can be measured only with a dyno. And if I consider the number of kms I drive when the filter is nearing a cleaning I'll bet I'm using more gas as the engine is trying to suck through a muddy gooey mess rather than a dry filter.

I think they are over rated. Also cleaning the oily mess every 10,000 kilometres (I drive in dirt) is no fun. My mechanic also said they will let more dust through than stock. But it's almost irrelavent as the particle size either one lets through is so small (<20 micron?) that, if you change your oil regularly, it has no impact on the motor.

I also had a problem with the seal on my K&N that ultimatly lead to the dusting and malfunction of the Idle Air Control (IAC). Despite the cost of replacement, it was a good warning the the K&N was leaking dust into the motor.

So I've gone back to the stock filter. I can also buy 5 of these for the price I paid for the K&N...7 if you count the K&N cleaning kits. By my calculations thats about 100,000 kilometres.

I dunno. It's like wearing a ball cap with the Nike slash on the front. It'll still block the sun without the logo.

Oh...whats an Excursion guy cruising an F150 page? Obviously I've got waaaaay to much time on my hands!

 

A search of this site will find that the vast majority of people who have tried K&N have had positive results. I personally have had no problems with mine.

If you haven't reset your computer, then do it now. Also check to be sure you didn't knock anything loose while installing the filter. Also, are you using an average MPG figure instead of just one tank?

 

Why doesn't Ford install K&N filters? Why don't they install radical camshafts or high performance pistons or any other high-performance parts? because not everyone wants high-performance! Just because Ford doesn't use a part doesn't mean it isn't any good.

 

thanks leroy, i was thinking the same thing. there are alot of things a dealer can do that they don't. i think it is an issue of cost for them rather than the mod not being a good one.

 

I've been using K&N on all my vehicles for many years, and I have no complaints.

I have noticed, that with MAF equipped vehicles, you have to watch the amount of oil used. If over oiled, it could get the MAF wires dirty/oily which will do very bad things to the way your engine runs, and your performance.

 

ATCman, this is an excellent post. I was just about to poise a post regarding the overall quality of the K&N air filters, because I have been considering getting rid of mine in my 5.4L.
My story in short is, before I left the dealers lot with my brand new 2003 Supercrew, I installed a new K&K air filter (at approximately 25 miles). Two other vehicles that I have installed them on with noticeable improvement have confirmed this method of madness. After a short while (two tanks of gas) I was at the dealership here in Anchorage, with a very sad face asking why I was only getting 226 miles to the tank full! They told me that was normal under the circumstances with a new truck, and that I should keep driving it so that the computer would learn my driving habits. Driving along on my merry way from the dealership my mileage did improve – only after I learned to keep the beast at 55 on the highway and use the cruse control almost 100% of the time. I keep a very light foot on the gas peddle, in fact you’d probably swear you were driving behind the “Little Ol’Lady from Pasadena” when driving behind me on surface streets here in Anchor Town.
My mileage has improved like I say, now I have been getting 12.5 and somewhere in the 13’s (I don’t do hardly any highway miles, only city).
After reading this post where it has been suggested that K&N’s aren’t all that they’re stacked up to be, I think I just might go back to the OEM filter and see what happens. One thing that I find interesting is that of the mention of resetting the computer by disconnecting the battery? Will this really reset the computer, or will the flash memory still have the “driving habit” information intact like I have been told. Is there really an efficient way to reset the computer and start all over again without a trip to the dealer or performance shop?

Best regards,

 

Remove power to the computer by disconnecting the battery, then turn the headlight switch on and wait about a half hour. You can rest assured that the computer has lost its information, because all the drive info is stored in RAM, not the flashable ROM. Leaving the battery disconnected for a while allows any stored voltage to be consumed.

 

I could sit here and write down the pros and cons of what Ford should install or not install from the factory for performance,but this is a filter in which has been proven to let excess dirt go by,doesnt quite fit right,and lets the MAF sensor get dirty.If you like cleaning your MAF sensor and taking a chance of breaking it and having to possibly put out a 100.00 or more for a new MAF,then by all means install a K&N filter.

One more thing,if you take your truck in for warranty work,why then do you remove your K&N filter?Leave it in;let Ford see what a good thing it is;not!