Chris M.

I have been browsing the forums for almost a month now and I am still no where with my truck that I just bought. I bought a used 2005 F150 4.6 4x4 xlt from a bigger dealer in the area and it has been nothing but a lemon. When I bought it I was under the impression it had a exhaust, was ok loud and yeah it was an exhaust. Nope turned out to be some hacked up exhaust and a supper short muffler, was maybe 8 inches long. Long story short, i put a stock muffler back on. Then I started driving it and oh boy my mileage sucks. I get 8.7-10.4 on average. The truck has a level kit (from what i can tell) and the dealer put 285/70r17 tires on it. The speedo has to close because i have set the cruise at 70 and looked at my gps i carry while riding, which read 71.xx. The truck has a K&N CAI with one of those filters to go with it. Mileage sucks. I could drive a semi around town and get better mileage. When I took the throttle body off it seemed to be rich and very black on the other side of the throttle body. Smelled rich too.

I also have the common iwe solinoid issue going on too and actuator issue. and there is a huge leak out of the right rear axle seal

So here is what i have done: Cleaned the air filter and cleaned the MAF sensor with MAF sensor fluid. I have been running non ethonol fuel and have been keeping the rpms 2000 and under. I also rest the computer by leaving the battery disconnected for roughly 15 min. 200 miles to a take is poor fuel mileage and im not even pulling a trailer. Any help or ideas on the mileage would be great. I am getting some 255/70r17 tires back on it soon in hopes that it solves the problem but something tells me no.

Thanks from the potato state.

redknight1

these trucks don't get great gas mileage

stcolorado

Word, but a 4.6 shouldn't be getting that low of mileage. He should average about 10-13 in winter months on winter fuel (assuming he is even some place cold) and upward toward 19 in the highway conditions...

Have you checked for any codes or pend codes? The 4.6L I have no familiarity with but maybe there is a start somewhere.

Scuba_Dave

I also have the same year/engine...13 to 14 is Winter mpg, close to 18 in warm weather
When they put the 285's on did they adjust the speedometer for the size ?
If your GPS is off from the speedo then miles traveled is also off & mpg

Why is the dealer not fixing these issues ?

You are disconnecting the battery to "rest" the computer ?
You do know it then takes 100 miles to "relearn" driving etc ?
Could be another reason for poor mileage

2slow05

something else is going on, i have a 2005 f150 supercrew 4x4 with the 4.6 with 270/70/17 tires and i average around close to 400 miles a tank, it comes out to close to 15.5 miles a gallon. Have you changed the spark plugs and COPS? If not i would suggest doing that first. How does the engine run while it is idle? Smooth or a little miss or something to it?

obusnizzle

and you bought this truck, why?

stcolorado

I agree... Often times cut mufflers and shady lifts are your #1 sign to steer as clear as possible. Truck might have the mechanical equiv of VD!

lewissa81

1.xxx mph off according to your gps isn't bad for a 9 year old truck. I wouldn't worry about that.

As 2slow05 said, it may be time for plugs. When it comes to the coils, I wouldn't spend a bunch of money to replace them in hopes of improving mpg. It is recommended that the coil boots be replaced with spark plugs though, and that could help. How many miles are on the truck?

Are both iwe actuators ratcheting, just one, or are they both locked in? That's going to make your mpg go down. Get that fixed and you should see an increase.

Leveling the truck can cause your mpg to decrease also. Not a whole lot, but some.

Your O2 sensors *could* be getting lazy and sending unreliable information to the computer. Even though people may disagree, I change mine out about every 100k miles just to be sure.

I don't know where you live, but if you have a bunch of hills or mountains, that's going to hurt you too. In my part of AL, we have mountains. I'll average 14-15mpg highway(I have the 5.4) going up and down them, but 18-19 mpg in flat terrain further south.

How you drive can have the biggest affect though. We all think we're the best (myself included), but none of us are as good as we think we are.

Chris M.

Wow thanks for the fast replys! I will try to answer all your questions but forgive me I'm using my phone. And to answer the chopped off muffler/why did you buy it? Well I was told it was a nice truck. Drove it and it drove fine was nice and honestly it looked good. Didnt do anything weird or nothing. So I bought it.

For the how is it running. Well starts and runs good. Sometimes it has a rough idle and feels gutless. Truck has 116000 miles give or take. And the last time I reset the computer was about a week ago. I do know these things like to learn our driving patterns.

Chris M.

Far as codes go nothing until tonight actually. Finally got a check engine light! All the dealer wants is a 100 dollars to check the truck out. But now that its on they might do it for free. Plugs and what not I have highly considered as the low end rough idle is kinda off and on. What has me worried is the thick oily stuff/fuel or whatever it is in the intake. Like behind the throttle body. Its messy. Im calling them in the morning to tell them what's up...again. If anything I can be a pain in someone's rear. I have done some research on a lemon law in my state. But I'm not familiar with it. Not jumping on the let's go sue em bus but would like to see them make it right.