MPG Drop: 2016 Sierra 2500HD - Gas Engine

[jimsto2]

I’ve got about 104000 on the truck.  In the past couple weeks my MPG has suddenly dropped from 13-13.5MPG to 10-10.75MPG depending on how & where I’m driving.
 

I did install a front leveling kit & new tires at the first of November but the MPG drop seems to be since Christmas / New Year timeframe.

 

I haven’t noted any change in other performance,.

 

Thoughts?

[CamGTP]

Do you have a fancy scan tool at all?

 

Something I always check on these virtual flex fuel vehicles (if yours is one) is to see what the reported alcohol/ethanol percentage is. Often times that data is incorrect and will cause a drop in mpg as it will use more fuel than it really needs too. Most fuel should be ~8-10% and when they act funky they will report 25-50%.

 

Not saying this is it but it's something I always check for.

 

Past that, clean the MAF sensor with the proper cleaner. Carefully clean and inspect the throttle body. Check air pressure in the tires. At 100k miles spark plugs should have been done.

[gone_fishing]

Cold weather fuel economy drop? I know my fuel economy drops substantially when it gets bitter cold.

[jimsto2]

Thanks.  I’ll check it out if I can get my hands on a scanner.  I can handle the maintenance items.