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Fuel Economy Problem

shrinee

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shrinee Enthusiast

shrinee

Posted
Posted

Hey, i have a 2004 Silverado half ton truck with the 5.3L engine in it. I have added a 3" level in the front and a 2" rear block. I put on 285/75R16 Cooper STT's when i got the truck. My engine light was on and i was only getting 9 mpg. i got it scanned and it pulled up a code for the oxygen sensor onces and max air flow. They told me to replace my max air flow so i did that and replaced the air filter too. Now i am getting 11 mpg which is still terrible. Does anyone know why i am getting such bad fuel economy or how i can make it better!? Thanks

Stevens03 Senior Enthusiast

Stevens03

Posted
Posted

Did you program for the taller tires cause the math will be off if you didn't leaving you to believe the mileage is worse than it is. Also what gears do you have in the truck? If you have 3.42 or worse, thats another reason your mileage is suffering.

 

I had an 03 5.3 with 4.10 gear and 35" tires and still got 13-14 in town, 18-19 highway.

Big Whiskey Senior Enthusiast

Big Whiskey

Posted
Posted

Yep, that little lift & bigger tires is probably the problem. You're driving a brick on wheels. I had an '06 with the same setup, and 3:42 gears. I averaged 12-13 mpg driving pretty easy. When I drove it hard, it got around 10-11 mpg.

Mulaka Enthusiast

Mulaka

Posted
Posted
If you have 3.42 or worse, thats another reason your mileage is suffering.

 

I have the 3.42 and I get great gas mileage. 19 city/hwy mix and 20-21 just hwy. :)

Stevens03 Senior Enthusiast

Stevens03

Posted
Posted

Look in the glove box for the RPO codes, GU6-3.42s, GT4-3.73's, and GT5-4.10's :)

 

Also G80 is factory lockers.

Big Whiskey Senior Enthusiast

Big Whiskey

Posted
Posted
If you have 3.42 or worse, thats another reason your mileage is suffering.

 

I have the 3.42 and I get great gas mileage. 19 city/hwy mix and 20-21 just hwy. :)

 

 

 

That's because your truck is stock. When you add a lift and bigger/heavier tires, the 3:42's suck.

Mulaka Enthusiast

Mulaka

Posted
Posted
If you have 3.42 or worse, thats another reason your mileage is suffering.

 

I have the 3.42 and I get great gas mileage. 19 city/hwy mix and 20-21 just hwy. :lurk:

 

 

 

That's because your truck is stock. When you add a lift and bigger/heavier tires, the 3:42's suck.

 

 

 

Ah, that makes sense. Good thing I have no intention of getting a lift or adding larger tires. Thanks for the info. :dunno:

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