There Is An Underlying Problem Here.... There Is Something Wrong That You Should Not Just Overlook....

How Many Miles Are On The Vehicle??

There Has To Be Some Sort Of Sensor Gone Bad, Or Not Calibrated Properly...

That Kind Of Mileage Is Not Even Close To What You Should Be Getting

 

i agree!!! i checked all the vac lines and ports, no leaks. i check the pcm daily, no codes.

i cleaned the maf with contact cleaner, and cleaned my k&n filter, and re- oiled it too.

the only thing i can think of is the fact that the temp was 0 to -17 here the entire first week i owned it.

also all but 20 mi of the driving was in town, and in 4x4

 

How Many Miles Total Does The Vehicle Have??

 

111,249

im starting to suspect that it has a 6.0 swap.....

my buddy and i took a similar 5.3 truck out with a cai, and 2 1/2 duals all the way back, and it was a dog compared to my truck. it had way less torque, and mine has stock exaust!!

the things that make me think that it's a 6.0 is the driver's side front most ehaust bolt has the head snapped off in the head.

also on the pass side the second coil pack from the front is new....hmmmm.

all things that could have been broken during a 6.0 swap.

sy0569

 

I didn't see any custom tune or programmer listed, so your miles being shown on the odometer are incorrect.

Because you put bigger tires on, your odometer is going to be off and show less miles than your actually putting on. Bigger tires take less revolutions to get from point A to point B.

You'll need to either get your speedometer fixed or figure out the calculation to find the correct miles.

What size tires did you have before?

 

You have won a prize... I agree with you totally on this.

 

Most people also like to run 4.56 gears with 35" tires which will put it back close to stock. 4.56 gears will make it easier to get the truck moving and should be better mileage especially in the city.

 

This makes perfect sense

 

hmmmm no tune yet. i just bought the truck.

i checked the casting#'s and it is a 5.3 litre block.

i know about the tire size difference, i add 9% to my mileage figures.

im up to 13.30 on the highway....sad

i also just found some stock duramax exhaust that was taken off a truck.

it has the same bends, and hangers,and it's 3.5 inch factory!!

cut off my factory stuff at the y, and welded up the 2.5-3.5 adapter.

also i cut out the stock deisel muffler, and put in a piece of straight pipe.

the sound is awesome!! im hopeing for 14 mpg now.

i checked my LT fuel trims while driving and the computer is still adding 9.4-11.7%

of fuel above base fuel map. when i started it was adding 13.4-16.7%

is there a way to lean it out?????