4.8L v8 Gas Mileage?

2004GMC1500CC · January 11, 2007

Hi, Im new here but i already know that something is wrong since i only get 13-14 mpg and i drive a regular cab 1999 4.8. I have 285 cooper ST tires on it but that still sounds horrible compared to what you all are saying.

Is this normal for the tires and 116k or do i still suck?

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Has your speedo and odometer been reset to match your larger tires?

swat · January 11, 2007

i haven't reset them which could make a difference but i am wondering if it would change that much. I drive mostly highway to school and back on the weekends. The thing is that the mpg doesn't change if i drive all highway cruising at 65@1800rpm on a long trip or if its all city. Maybe its my driving habits but i just don't see my numbers adding up to these other ones.

wriley4409 · January 11, 2007

How did this scangauge mount in your vehicle? Is there a pod that comes with the tool or did you have to buy it separately?

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I simply set the unit on top of the dash, wedged between the windshield and the pillar. Similar to the picture below, except that mine is positioned to the far left:

Gmc420 · January 22, 2007

well maybe something is wrong with my truck, i have an 06 single cab 4.8 and i am only getting 13.5-14mpg. i do have a flowmaster muffler with the tubing cut right after the muffler and a drop in k&N. i thought those improved mpg. am i wrong?

eyeball03 · January 22, 2007

Same here! The best city I've gotten is 14.4 mpg! I do run 20's magnaflow, and K&N dropin...I recently installed a HPP3,(corrected the tire size) and I'm going on a road trip this Afternoon, so I'll let ya'll know if it helps the mileage

Gmc420 · January 23, 2007

c'mon dude help me here.

SilveradoLAX7 · January 23, 2007

06 2wd WT regular cab with 4.8 V8.....I can go ~640 miles until the low fuel light comes on.

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Is that with an aftermarket 100 gallon gas tank?

I've pulled better than 600 mi on a tank durring road trips.

-Jay

TonyMazz · January 24, 2007

I would suggest that a K&N filter (besides adding dirt to your engine) will increase the flow...however, the computer will adjust and add more fuel.

folks are seduced by "added horsepower" adds ....there is only one way to "add" horsepower.....burn more fuel!!!

Gmc420 · January 25, 2007

i always thought, more flow better mpg as long as u rnt punchin it everywhere.

cerbomark · January 25, 2007

4.8 4x4. 3.42, 20 in wheels,07 crew cab, 1500 miles, 14/city, 18-19 highway @65-75 mph. Thought it would be better? A pcm tune to come soon, which has helped my mpg in the past. A more effiencent tune CAN give more power with less fuel.

Gmc420 · January 26, 2007

so can someone awnser my question of why i am gettin s**tty mpg??

eyeball03 · January 27, 2007

The Road trip is over... 18.5 hwy, ave 70 mph 2k rpm, city drivin 15.4....on my return trip I got 19.1, Thats an improvement over the mileage I was getting before the HPP3...not much tho!

GatorFan · January 27, 2007

so can someone awnser my question of why i am gettin s**tty mpg??

Just my opinion but have you checked the plugs to see what they look like? What about the air filter? All may seem like basic knowledge questions, but I noticed a huge loss in MPG on my wife's 4X4 Runner until I checked the O2 and plugs. Replaced O2 and plugs and it came up and average of 3 MPG. I noticed you said you swapped out the filter with a K&N drop in but now it may be dirty. One of your injectors might also be losing power as well but not enough to throw an engine code. I would begin checking the obvious things first.

I also added a HPIII Programmer and noticed a better MPG average. I am planning on removing the programmer and getting a PCM tune instead in the near future.

Of course, each truck is different and what causes one to lose MPG, might not affect another.

Just my $.02.

polyanskiyalex · January 27, 2007

My 4.8 has over 100,000 miles on it and still gets 20 mpg driving back and forth to work(20 miles each way, 12 miles of freeway). Of course the rear end gearing in this thing has me hitting 1700-1800 at 65 mph. It gets the same mileage as my wifes' 4 door Tacoma PreRunner. I can't imagine the 5.3 would do much worse and has a few more ponies...

a little off topic. What size of tires do you have on those escalade wheels. I just picked up a set and was planning to switch my oem generals onto the escalade ones until i buy new tires. I have a 2wd long bed like yours.