2014 Sierra 5.3L HORRIBLE MPG...HELP!

[freshstart12]

I'm now consistently around 16.5-17. Dependings on my driving style.

[Bowtie619]

Speedo been re-calibrated? My 14 was getting 14.2 with 285/65/20's with the speedo being about 5mph off. I bought the hypertech and calibrated it, now it stays between 16.5-17mpg.

What did you set your tire diameter to? I want to test and see if I can bump my size up even though I only have stock just to see if it properly calibrates the Speedo....THanks

[gilleydog]

try a can of seafoam in the gas tank (put in when low on gas)

[ic3man5]

try a can of seafoam in the gas tank (put in when low on gas)

 

This won't do anything for Direct Injection engines.

[BigBadSierra]

 

This won't do anything for Direct Injection engines.

 

 

CRC intake valve cleaner is what I'm going to try. Just have to wait as it's not on sale in Canada yet so Father-in-law is bringing some home for me from Florida.

 

From what I've heard is it works.

[ic3man5]

 

 

CRC intake valve cleaner is what I'm going to try. Just have to wait as it's not on sale in Canada yet so Father-in-law is bringing some home for me from Florida.

 

From what I've heard is it works.

 

I'm going to try this next, I did the seafoam spray and it seemed to help but once you notice it you are probably past the point of just one can working 100% (My idle was getting rough and MPG was dropping at the same time).

[Ezekiel2517]

16-17 isnt bad for mixed driving. You wont see 20s until you are out on the highway. Even then, if you are hauling serious a$$ or have a headwind you still might be in the 18-19 range. Mine averages right at 21 with flat and level highway at 70 with no headwind. But if I get outside of those parameters, it drops a few MPG. Around town I do 15-16.

[hurricanoday]

I was a little shocked to see my 15 denali at around 11mpg in the city last tank, but I was doing all short errands stop and go in the city. Soon as I hit some hwy I was back up to 17-18mpg for the tank.