I hear that this is pretty much horrible mileage for my 4.8 and am just tyring to figure out what it could be? My only mods are K&N FIPK2 and a 3in,out maganflow on stock piping, all the guys on FSC are saying I should be getting somewhere around 18-19...wtf? I pretty much granny it as much as I can and still get crappy mileage...any ideas? I use regular oil, 87 octane from shell religiously and have know clue what it could be?

Oh, and my truck is an 03 4.8 with 4000 miles, if that helps

 

Seems normal to me. I have the same truck, similar mods, I get about 14MPG in the city with easy driving, and 18.9MPG(best ever) on the highway at about 70MPH.

 

Don't know what to tell you. I have a 4.8 with no mods with 3.73's and 255/70/16's. I average 18.5 with a 50/50 mix of highway and in town driving and have gotten as high as 20mpg. Have you checked the pressure in your tires? I know this can make a huge difference in your mileage.

 

Lift the pedal

 

I have a 99 5.3 extended cab and have gotten 19 MPG on the highway with my K&N and cat back system, so i don't really know what's going on. Does everything seem to be running right, do you smell any gas or anything?

 

i have a 5.3, headers, no cats, cam has been in since last wednesday afternoon and i had half a tank then and i havn't filled up yet, and i drove to denton from azle and kennedale from lake worth, and back and forth to work 3 times...about 250-275 miles on half a tank...pretty much highway miles but still it's good for the mods and how i drive

 

nope don't smell gas or anything and it seems to be running perfectly, I have no clue what it could be. Could it be with the intake and exhaust I am creating to little backpressure? I know it sounds stupid because everyone else has like no cats, headers, intake, and such and still have decent gas mileage but that is all I can think of, so...any more thoughts? I am getting oil change number 2 tomorrow so I will see if it helps anything. Should I maybe try a higher octane gas? I have no pinging though just curious if it would help my mileage?

 

03rado, i think you're kinda par for the course, you have a somewhat small engine pulling around an extended cab truck, not flaming on your motor just saying that the less power the motor puts out the harder it is to pull around something that a different motor with more power could pull easier. it's a simple theory but true.

 

How long is your drive to work? What kind of driving do you do? K&N need to be cleaned? I had about a 10 min drive (couple of miles) to work and in my 5.0 was getting about 12mpg due to the fact that it was still running rich to warm up.

 

what was your trucks GAS mileage rated at on the window sticker. I think my 5.3 was 16city -18hwy. If it is completely out of line I would take it to the dealer. The mods you have should increase your mileage as well. If the dealer says there is nothing wrong, tell him he is full of ****. They can swap the motor under warranty. That is if your truck should get better mileage, if it is in line with other 4.8 excab's you are SOL. They might say no, but if you pitch a big enough fit they will swap it.