Fuel Economy Problem

[shrinee]

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

[cghbuilder86]

Probably the lift and tires. Those two things kill your mpg. Only thing I would recommend is drive slower. Thats how I get 20 ;)

[Mckenzie]

Yup thats about what i get anywhere from 10-12 in city/town driving

[Stevens03]

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]

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]

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.

[shrinee]

thanks. i am not sure what gears i have to be honest.. ill take it into the dealer to see

[Stevens03]

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]

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]

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.

 

 

 

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