MPG fuel efficiency reduction help

[ss_hobby]

I have a 2005 expedition that has recently had a significant drop in mpg. I normally could get between 15-17 mpg with this but recently it has dropped to 12 or less. I did not make any changes nor do I have any codes. I replaced the air filter, ran seafoam through the tank and cleaned the throttle body. I think this may be a simple fix but need to know where to look. Has anyone else seen a drop like this? Only thing I can think of may be a pcv valve or something. I was getting 12 mpg when I was towing my boat and 12 ft enclosed trailer prior to this but havent towed in a while to see how bad my towing mpg has become.

 

[tonydiv]

I have a buddy who religiously tracks his mileage and he swears that his mileage will change depending on where he fills up.

Are you buying gas at the same station?


Things to try:
Cleaning the mass air flow sensor. There's a special spray for it.
When was the last time the fuel filter was changed?
Are tire pressures where they should be?
How does the truck feel during slow, tight turns? (IWE failure)
Buy a locking gas cap. (don't laugh, it happens)

 

[ss_hobby]

It's usually at Sam's Club. That could be the issue, never thought of that. I will try to run a couple tanks at another station to see if there is a change.

 

[tallsville]

I've noticed i get less mpg when i fuel up at arco vs other stations.

 

[metaldrgn]

Did you do any maintenance prior to noticing the drop in mpg? When is the last time the spark plugs and/or cops were changed? Does it feel like the engine misfires from time to time?

 

[ss_hobby]

Fuel filter and spark plugs were done around 15k ago. MAF sensor was cleaned recently when I changed the air filter, tire air pressure was bumped up to see if it would improve.
It idles just fine, no hesitation when giving it gas. Everything is good except that fuel mileage.
The wife is driving the truck now so that could be part of the problem. I will post back after I run through a couple tanks of gas from another station. Should be in a couple weeks. If anyone has any other ideas or experience with this let me know.

 

[ss_hobby]

Update

We went through a few tanks of gas. Sorry it took so long to post another reply, the wife had surgery and I was driving the more fuel efficient vehicle. We have been getting anywhere between 11.2 mpg at the low end and 13.2 mpg at the high end.
I am pretty sure its not the IWE failure and the fuel filter was changed at 100k.

I had someone tell me that it is common for the Cam Phasers to get clogged and cause a drop in MPG. Has anyone heard of this?
I did a little looking into this and people were saying try and put heavier oils in ie 10-30 to 10-40, one guy was even running Rotella. I guess the reason Ford requires the 5w-20 is that the oil ports are small and the thicker oils will be bad for the engine. I found a youtube video of a guy that had bad cam phasers and began reading the comments. Probably the only person on there I would trust was an F-150 owner by the name of Mike Turner who works for Ford. Here's one of the things he said;

"Springs in phasers (not the big coil, but the ones inside phaser get weak and cause incorrect timing. There is no tsb from Ford about this being ok. Their recommendation is to replace both solenoids. This is bad for the engine to not repair. As long as inside of engine is not sludged up the only proper repair is to replace both cam adjust solenoids, cam sensors, and both phasers. The phasers are a pain to do. Need wedge and cam holder tool."

Sounds like big bucks to me. I guess I am lucky because a lot of people are complaining of rough idle and loud noise at startup. Guess my fuel mileage problem isn't so big afterall. The only things I picked up on there was use 15-20 oil and USE ONLY MOTORCRAFT OIL FILTERS. I guess the filter contains a drain back valve preventing all the oil to drain into the pan when idle. I wonder if I should discontinue using Lucas Oil Treatment or use only half the qt next time.

Well anyway, if anyone else has a recommendation to improve the fuel mileage, let me know.

 

[gulfman]

I can only comment on the gasoline end. I was in the gasoline business for over 40 years. In todays market place, you engine will not know the difference between one brand or the other. It is all blended to the minimum Federal standards due to environmental regulations . (At one time that was not true.) Just make sure you buy from a location that is very busy and does not look like a foreign dump. One brand will not change your MPG versus another. Good luck.

 

[2005Expedition]

is that highway miles or in town miles ? in town sound about right 10-13mpg. highway around 17-19.

 

[Hamfisted]

I would recommend using synthetic oil, wash and wax your Expy, run the tire pressure at 40 psi . You should see at least 18 mpg on the highway. If your motor's not running rough it's not your cam phasers. Throw some Berryman's Chemtool gas additive in your fuel tank once a month to keep your injectors clean (available at any Walmart...).



-Mike

 

[ExpeditionAndy]

SS_hobby,

This is just a thought. If you are using the mileage computer in the instrument panel display, this is an average of the last 500 miles driven. If you had done a lot of highway miles and then drove 500 miles of city driving you would see a reduction on MPG on the instrument panel. You can reset the computer by holding the reset button the right of the gear selector for 3-5 seconds. That will give you your current mileage.

I have also noticed that my mileage drops when I switch from real gas to gas with 10% ethanol. I see about a 2-4 MPG drop. I notice this when we drive into PA and have to fill up there and drive back to IN.