mpg for 04 5.3 'burban

[rickpilgrim]

2 weeks ago we found an 04 Z71 suburban loaded w/leather dark green w/84K mi w 5.3 engine. We don't drive it like we stole it or granny it either but the best mpg we found from full tank to low fuel light has been 12.5 mpg There is nothing wrong with it so is that about right or....

[69gmcc10]

In my silverado with a 5.3 that is about the mileage I would get in town during ethanol blended fuel season. When I used real fuel I usually got about 15. Stop and go traffic isn't exactly awesome.

a few things you should try is cleaning the mass air flow sensor with "MAF sensor cleaner", run some sea foam through the intake (dump in through the brake boost hose) and also run the rest of the sea foam through the gas tank.
You may also want to add a K&N filter into the stock box (having added just K&N replacement filters and intake systems on many vehicles I feel the bang for the buck is just the filter).

[Bowed]

The EPA says around 14 average and 17 highway for all models of subs - 2wd , 4wd and Awd . That does not mean you will get what the EPA says , but it's a good reference point . I have the Silverado ex-cab pickup with a 5.3 / 3:73's / stock tires . The very best I can do is 15mpg even with a lot of easy highway mi . Running the air 100% of the time in hot weather it drops to a 14 avg and if I step on it just a little , then it's 13mpg . I like my truck but the mileage disappoints . They should have been doing better with these newer trucks , because they had the tech ability to do so . My 5.3 is not that fast or that powerful either for the amount of gas it burns . My buddies Tacoma V8 w/extra cab gets 20 mpg . It does have less payload capability , but with 5 to 7 mpg more then me , I feel he wins .

[Special-Ed]

i average 14 combined on mine... i have the e5.3 and a 4.10 gear set

e-85 i get 12 combined...

highway driving...17-20 depending what state and what kind of fuel.

between chicago and florida and back i get 18 with cruise set to local speed limit and 100 gas purchased on tank 2 and 3

[hopped up]

i get 15 with a lift and 35inch tires . but i have the 4.8
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[69gmcc10]

With my 4x4 5.3 x-cab silverado z-71 with 3.73s I got about 16-17 on the interstate and if I could keep the speed below 70 I could get about 19. I got 23 mpg at 65 mph on a trip once, had to do the math 3 times to make sure I didnt make a mistake, but despite my best efforts I never saw those numbers again.

[Bowed]

Originally Posted by 69gmcc10

With my 4x4 5.3 x-cab silverado z-71 with 3.73s I got about 16-17 on the interstate and if I could keep the speed below 70 I could get about 19. I got 23 mpg at 65 mph on a trip once, had to do the math 3 times to make sure I didnt make a mistake, but despite my best efforts I never saw those numbers again.

What do you get for an all around mpg average ? Both of our trucks are the same (4x4 5.3 x-cab silverado z-71 with 3.73s ) but you do better on highway mileage . I can drive at 65mph using the cruise control and still get only 15mpg .I have nothing installed on the truck that would create a drag . It's stock height and stock tires .

[Special-Ed]

Originally Posted by Bowed

What do you get for an all around mpg average ? Both of our trucks are the same (4x4 5.3 x-cab silverado z-71 with 3.73s ) but you do better on highway mileage . I can drive at 65mph using the cruise control and still get only 15mpg .I have nothing installed on the truck that would create a drag . It's stock height and stock tires .

what kind of tires are you running and what is the pressure... i got rid of the off road tires and put on regular street tires... rides much better and picked up 1 mpg

my 05 suburban z71 with a 4.10 does better than that. mine is completely stock.

65 mph 10% ethanol gas i can get close to 20mpg

sounds like you have a problem somewhere.

[Bowed]

Originally Posted by Special-Ed

what kind of tires are you running and what is the pressure... i got rid of the off road tires and put on regular street tires... rides much better and picked up 1 mpg

The tires are new cooper light truck 6 ply highway tires with a touring tread . They are stock in diameter and tread width . The max pressure for the tire is 50# . I live in the Arizona dessert and the tires get really hot in the summer heat on scorching asphalt , so I keep them at 35#. You do make a good point and when the temperatures here drop under 100 degrees , I will try 40# . Thanks for that reminder .

[rickpilgrim]

We have Michelin street tires on our burban and they are at 50#
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[69gmcc10]

Originally Posted by Bowed

What do you get for an all around mpg average ? Both of our trucks are the same (4x4 5.3 x-cab silverado z-71 with 3.73s ) but you do better on highway mileage . I can drive at 65mph using the cruise control and still get only 15mpg .I have nothing installed on the truck that would create a drag . It's stock height and stock tires .

Every time I feel my mileage goes down I clean the MAF sensor and run a heavier dose of sea foam through the tank. But I personally feel the big driving habit that helps overall mpg is I dont use the AC unless my wife is in the truck or it is ridiculously hot (know I am saying this to someone in AZ). The defroster also uses the compressor so I use it as sparing as possible.

More info on my truck: I also had a cold air intake form spectre, and it helped a little on mileage, but not much (it did more for top end power than anything). I run Mobil one oil and I think makes more difference than the intake. For tires I run the minimum ply tire that meets the trucks rating and now I run 265/75/16 Toyo Opencountry ATs at about 35 psi.

[LEEVON]

12.5 is cause for some investigation. As mentioned, clean the MAF and use seafoam. If it has a PCV valve, replace it (somewhere around 04 they quit using them on 5.3's). Replace the fuel filter which is cheap and easy.

Without any codes from there it's more complicated I think. Checking fuel pressure, cleaning injectors, catalytic converter check, etc.