Hey I'm a new member and I have done some research on this but having a hard time finding an answer.
I just purchased a 2002 f150 supercrew lariet FX4 and am realizing after just 2 days of driving it that it is getting horrible gas mileage. I hav'nt even figured out the numbers yet but its obviously horrible. I've owned fords before even my old 460 didnt do this bad.
I noticed it has a K&N filter and intake. I have also read on the forum that stock filters are the way to go but I dont have the stock parts.
Is it possible to use a stock filter on the K&N intake setup or do I need to get the original enclosed box?

 

The K&N itself should not be the cause of bad fuel mileage. If it was over oiled, it can foul the MAF and MAYBE cause bad mileage. What about other things? Is the truck lifted? Do you have aftermarket wheels and larger tires? In stock form, that truck would probably average 11 or 12 around town and maybe 15 or so on the highway. I would clean the MAF, clean the throttle body and put in some new plugs. Has the transmission fluid been changed?

 

Really kind of depends on what you consider as "bad gas mileage." On a 2002, the K&N system should not effect the fuel mileage at all, had one on my 98 and it really woke the engine up. If it was an 04 and up then without a tune it will cause all kinds of plug issues by running lean. I'd say new fuel filter, plugs and injector cleaning would be your best bet.

 

I just put new tires on stock wheels 265s. No lift. I was going to clean the MAFs when I swapped out the filter. Im not sure how to clean a throttle body but will look into that as well.
I am scared to check the plugs because of all the horror stories associated with breaking them off and costing $1000 to have them done at the shop.
transmission fluid hasnt been changed. It seems to shift great. Very smooth.

 

The plugs in that truck do not break. You are at risk of one blowing out if they are not torqued to 28 ft lbs. They plug change is straight forward, just torque them to 28 and you should be fine. There is an writeup in the Articles and How To section that tells how to clean the throttle body. Check the index.

If those tires are taller than the original tires, than you are going more miles than the odemeter is recording. I have no idea what the stock tire height was, but see if you can get that info from a manual.

 

So as to my original question then, should I just clean the K&N or get a stock setup?
obviously at the same time cleaning my MAFs and throttle body.

 

If it were mine, I would do all the other maintenance first. I can not see a different filter element in the K&N system making a difference in mpg. If can find any other source of the poor mileage, then I would check wrecking yards for a stock system. I just really doubt that is a source of bad mileage.

 

well the truck came to me with 265s so I put 265s back on. I just looked it up and 265 IS stock size.
everything I'm reading about changing spark plugs sounds opposite of "straight forward". one person said could even take up to 6 hrs if you've never done it on this engine. I know my way around and don't believe it would take 6 hours but that's a bit disconcerting.

 

I think you are reading about the 04-08 spark plug removal.. The spark plug change is straight forward on your year model truck..

I would change plugs, cops, fuel filter, clean maf, clean throttle body, change o2's then see where you stand.. If your still getting crappy mileage it would be a good time to check your cats on the exhaust.

Your intake in not causing the bad fuel mileage.

 

OK. Thanks guys! Good to hear.

 

Do a full tune up and see how it is. Depending on your miles it may be crying for it. What is your expectation of gas mileage for this truck? If you are getting 9mpg there may be some bugs, if your getting 12/13 then you are on par with real life mpg. Your rear end gearing may be too high for your driving area and it might be working hard to take hills.

 

I realize its a truck and my expectations arent high. I have yet to calculate the actual MPG so we'll see by the end of the week when i fill up again.
Thats one of the main things ive noticed is when going up a grade it seems extremely under powered. I have to shove the pedal all the way to the floor for it to shift down into 1st gear for it to start to acceleratre. seems a truck this size with this engine shouldnt have to work so hard to get up a hill. I cant even imagine what will happen when I pull my camp trailer.

 

sounds like it has some issues, but as stated start with the maintenance and then go from there


is it throwing any codes?

what gears does it have?

 

no codes. seems to run well but just seems underpowered going up the hills. Ive never had one of these trucks so I'm not sure what it SHOULD feel like. Just seems to me it should shift down sooner than it does. Im not sure what gears. How can I tell?

 

the door tag says h9 which appears to be 3.55 gearing.
After doing some reading it sounds like a programmer might be in order....after my tuneup and I save up some doll hairs.