I know some of the things to get better MPG are pretty basic, but I was wondering how to figure out why my 4.6l 2010 f150 stx is not running so smoothly, its running pretty rough and last month I was averaging a total of 16mpg and now I am at 13.9. I am not heavy on the gas, I don't race around, tires good, oil was just changed and filter is not bad. Something isn't working right. Any help? Thanks!


Josh woods
2010 f150 stx 4.6L

 

Have you checked to see if there are any codes?

 

Check engine light isn't on, will it still show up a code without it coming on?

 

You have to have a scanner hooked up to it to read some of the codes. Wouldn't hurt to have a data log or live streaming scanner. Sometimes a missfire will not trip a check engine light. How many miles are on it and what have you replaced/fixed since you've owned it?

 

107XXX and so far I haven't had to touch it, I bought it at 86XXX miles, been running strong ever since. done the regular services and kept up to date on everything. but nothing replaced.

 

Do you know if the plugs and COP's have been changed? They're due if they haven't been yet. Definately go back with Ford parts as some of the aftermarket stuff doesn't play well with the truck. At the very least, it might be a good idea to pull a couple plugs to check the gap.

 

I would change plugs and run a 20oz bottle of techron through the tank. Bet it smooths out

 

Hi there s a plastic modul just beside the spare tire that control the fuel pompe and sometime it gets cracked and the water get in and then idle gets rouph , easy to see happen to me once ,,

 

Thanks, I will go check these out, atleast its a start and hopefully itll clean things up.

 

It's probably due for a basic tune up if you haven't had any other services done to it except oil changes.

1. Check your grounds
2. Clean the battery terminals
3. Plugs and COP's
4. Air filter/fuel filter
5. Check diff level
6. Check steering components
7. Check brakes

There's some more, but that's the basic start.