<!--[if gte mso 9]><xml> <w:WordDocument> <w:View>Normal</w:View> <w:Zoom>0</w:Zoom> <woNotOptimizeForBrowser/> </w:WordDocument> </xml><![endif]-->I'm new to this website and I joined because every time I've have done a web search, this was the place that had answers.

I recently bought this sweet 05 F250 that an old retired couple had only used for their fifth wheel camping in the summer time. It has about 60k miles.

This truck is only getting 13 mpg for mostly highway driving, which is way too low.
I have been to the dealership and done a software update but it didn't help. I’ve also used some diesel injector cleaner (twice…Gunk) and that hasn’t helped get better fuel economy.

I'm starting to think that it's the fact that the turbo is always at about 8-10 psi when I'm driving down the highway at about 70 mph (average speed). No head wind, no hill, the truck and box is empty except for me and I'm not hauling anything. The turbo seems to be on most of the time unless I take my foot off the gas or coasting down hill.

The only aftermarket thing this truck has is a big K & N filter and intake tube. By the way I have been told to go back to the original air intake system and I’m doing that.

I need the help of the experts on here.

 

Is this a 4wd truck and what size tires does it have?

 

It is a 4W drive with stock sized tires.

 

an erroneous MAF reading can throw off fuel economy I believe.

 

Which excess oil from an over oiled cotton gauze air filter can give you....

 

(to both you guys...) I did clean my K & N and could have easily over oiled it. So this means that the engine would be running 'rich' then? Not getting enough air? Or is the oil on the filter actually getting into the system?

Man I'd love it if all I have to do is find a used air intake system and put it in to make this better. I'm on the hunt for one now.

 

The stock air cleaner is great to 500 hp, you should think about reprogramming your ficm and possibly a computer strategy roll back from; http://www.gopowerhungry.com/_ficm.shtml

 

Oh - some 2005's did not have a MAF. You might check to see if you have one!!

If you have one, you might try MAF sensor cleaner first (get a MAF sensor cleaner from the Auto Parts store) but the K&N itself could be contributing.

Be aware that there are quite a few things that can affect fuel economy - but the aftermarket air filter itself could very well be a contributor.

 

I'll check to be sure that it has a MAF but, I'm pretty sure it does. That's the sensor right after the air filter reset button on the intake right?
I'd clean it just to eliminate the potential of a problem.
If the MAF sensor needed cleaning would it already have generated an error code? Cuz if it does then I'd do that first to find out.

 

Yeah, I believe the MAF was taken out in the Nov 2004 + manufacturing date (and added back in with the 2006's. The early 2005's had the MAF.

You could have a code without ever getting the CEL. An AutoParts store could probably check for codes for you.

 

I will check for codes tomorrow....for sure.

I just used 30 gal of fuel for 420 miles of driving. Costing a fortune because diesel here is now at $5.00/gal. Gonna fix this fast.

 

14 mpg is not too far off from what to expect IMO. 15-16 for mostly highway is my experience. A lot depends on the wind also.

 

Shiuld be about 40-50% better on the highway. More close to 20 per gal.
This gas more like gas mileage. Awful.

 

If the turbo is constantly pushing 8-10 psi while cruising at 70 on the the highway then it sounds like it may be sticking. Time to have it cleaned it may not help your fuel economy but it will save you money in the long run one way or the other.

 

There must be a way to do this so its super clean and non corrosive. Don't want it fairly clean and be out of balance...spinning at those speeds.
Is there a good way on this site?