Chevy Sonic LTZ 1.8L doing 17- 20 mpg

[rvilla2279]

im getting 17mpg it can get as good as 20mpg on hwy, im still breaking my head why, all maintenance done in time,i have checked the intake for leaks and installed new air filer , has new intake manifold from dealer which comes with new injectors built-in ,new oem spark plugs serpentine belt with new pulley new battery new coil pack new battery , and recently also replaced vacuum lines im using synthetic mobile motor oil, i have no check engine light. i tryed replacing the 02 sensors with basic after market drove for a month the was no change in mpg i then cleaned and reinstalled stock bosch 02 sesors also no change in mpg i did an alignment also replaced all tires and kept all equal recommended tire pressure on them . any ideas on what to do next for my poor mpg?

 

[Casual Observer]

Yeah that's definitely not right. I wish I could help, hopefully some one on here can!

How many miles and what year is your sonic? That's a pretty dramatic drop in MPGs to be something routine like tire alignment, oil, plugs/coils and you've replaced them. Was this happening before you went to the dealer to get a new intake manifold and injectors?

 

[aagcnet]

Check your engine temperature, if it is running too cold it will consume a lot of fuel, get a scan done looking at the datastream it may show if fuel mixture is running with low oxygen i doubt you are getting misfires as almost everything is new.