Compared against my old X with the V10 this thing seems to have hardly any power and is sucking fuel like there is no tomorrow, around 9.5mpg.
Company truck that my boss bought so I didn't get to test drive it, he did though. I think I even got passed by a moped last night. I have wondered this since I got it a couple weeks ago but just figured I would ask.

 

I guess it depends on what gear you have. My 03 SD 4x4 ex-cab 8' box was ok with the 5.4 but it had a 4.10 in it. I could pull anything but couldnt pass a gas station. It would get about 9 mpg loaded, empty, or pulling. Remeber you also have 2 less cylinders and a lot less torque too. It worked well in my F-150 with a 3.73...but I did put the Edge Evolution on it and that really woke it up.

Sarge

 

It's got the 3.73 in it.

 

I have an '07 with 3.73 gears. (See sig and pic) Driving unloaded in the highway I get 16-18 MPG. Around town I get 10-12. Mixed I usually get 14. Towing the trailer unloaded I got 12, loaded usually 9-11 depending on the weight. Red has no problems pulling 8000 pounds of trailer and antique Pontiac.

Mine isn't a dog at all. I can easily smoke the tires. While the V-10 or a PSD will out pull my truck, it does the job for me nicely.

 

I think the next time I can i will drop it off at our mechanic and have him give it a tune up.

 

It may just need a fresh set of plugs, check the COPs and a new air filter.

 

you know, it almost acts like there's something dragging it down. Almost as if it's a 4 cylinder with 100k and you just turned on the air conditioning. I just filled it up and it took 23.23 gallons in 196 miles.

 

Mine runs like a raped ape.... ??

MPG sucks though... 10-11

 

Yes it's a dog.

A loyal, steadfast, long-lived, man's-best-friend kind of a dog that will give it's all and keep going until you put 'er down...

Something sounds fishy.

And on top of what others have already said, clean the MAF.

I'm wondering, with the VVT (really, VCT), if it can get stuck and the PCM won't know it's not working right and not like the CEL?

 

theres probly something wrong with it. when i first bought my truck millage sucked (7 mpg unloaded) and power sucked i kept bringing it back to the dealer and they said there was nothing wrong with it and i cant expect a big truck to get good fuel millage. at 33000 miles the number 8 rod went through the side of the block and the new engine is much better gets 12-13 mpg in the city unloaded and it seems like there is alot more power.

 

Was it ever determined what cause the rod to let go? Spun bearing, or the piston/pin came apart? Just curious.

 

cause was undetermined they even flew in a tech from the kentucky truck plant who said what the hell were you doing, i have never seen one of these throw a rod. My response driving up the mountain to my house like i do every day

 

Dang... typically that would've happened to you 3001 miles later

Yeah, I wouldn't call the 5.4L a dog. Mines only the 2V and has plenty of power for me. I do have the 4.10s though and that does help.

 

Cats partially plugged perhaps?

 

My 5.4 is by no means a dog, and given the times I driven V10's unloaded they felt exactly the same.

I do know for a fact they will win a drag race against a ZR1 S10 and blazer... my roomate has one and I love rubbing his nose in it

Check your exhaust for clogs, 9.5 sounds a little low. As previously suggested, a good tune up should do the trick. Cold weather makes these things use a lot more gas though!