Hey guys I need some help I've got a 2008 Lariat Super Crew F150 with just over 62,000 miles on it. All stock! It all started about 4 months ago just before it hit 60,000 miles. My MPG's went down dramatically from about 17 miles per gallon to 12 per gallon (highway) I started with all the obvoius things before i took it to the dealer. Oil change, Air filter, Tire pressure, Fuel filter. All service has been done by Ford, and I've always ran good gasoline 91 octane from Chevron or Shell. The dealer has checked the injectors, catalytic converters and did a Fuel system check where they drove it around town for 45 mins. while it was hooked up to the lap top monitoring fuel consumption. And all they can say is "weired" no actual explanation for it. So I'm turning to you guys my F150 brothers for hopefully some insight.
Any info if greatly appreciated. Thanks

 

Did they......
Clean the MAF?
Clean the TB?
Check the parking brake....make sure it wasn't hanging up?
This happened 4 months ago...wierd......I know winter blend hit the market approx 1.5 months ago where I live....that usually makes the truck lose 2-3mpgs.....

Did the gas stations switch suppliers? Formulas?

Edit....
How are you tracking your mpgs?

 

You're using 91 without a tune? Why? You'll probably get better mileage with 87, what your truck calls for.

 

You dont need a tune to run 91. Its not getting him any better gas MPG though your right. You shouldnt waste your money on 91. Engine is huge it doesnt need 91 because it doesnt have a high compression ratio like european sports cars for example.

Yea I would definitly check the parking brake to see if its okay before you do anything else.

 

Weird, but what about some sparkplugs or something like that?

 

NO,

He will NOT get BETTER mileage by using 87. He'll get the exact same.

But he IS throwing away money due to the simple fact that one gains absolutely ZERO by using a higher octane fuel in a motor tuned for a lower octane fuel.

The ONLY DIFFERENCE between one octane rating and the other is this :

The HIGHER the number, the MORE RESISTANT it is to pre-detonation commonly referred to as ping.


!!!!!!!!!! STOP WASTING YOUR MONEY ON 91 !!!!!!!!!!

 

Or, he could get a programmer with a 91 octane tune and really have some fun/get better mileage.

 

Sorry, can't help, but if it makes you feel better, my truck has routinely gotten 12-13 mpg highway, since I got it. I feel your pain.

 

He will get slightly worse mileage by using 87. When you use 91 the knock sensor allows for more timing advance.

 

Mine ru ns exactly like yours with summer gasoline i get 16.5 mpg, right now im only getting13 to 14mpg , i have a 2004 fx4 34 inch tires 61k miles, dont worry

 

Dude... My truck pulls close to 19 mixed... I'm struggling to get 15. It sucks

 

You're kid'n right?

The only decrease you'll see is in your wallet. There is no benefit to using a higher octane than what the motor was designed and tuned for. NONE. This has been discussed at nausea on this and every other automotive forum on the net.....

 

damn that winter blend gas...

 

Advanced timing improves efficiency to some degree. Nausea or not, this is my story and I'm sticking by it. I can document very slight gas mileage and 0-60 time improvements with 91-93 octane over 87 octane on vehicles that use knock sensors. The performance improvement is only detectable with a stopwatch, not a butt dyno. However, it's not worth the extra cost.

 

My truck has higher mileage (130,000) Running 89 octane, I gotta say it has a little more power, and the mpg seems slightly better.