Hi, I have 2008 chevy 2500 express van 4.8L with 110,000.
I noticed that my fuel economy was down from 10.5mpg to 8.5mpg in matter of 2 weeks.(500 miles driven )
Every week 1mpg lower.
No changes to driving habits,correct tire pressure, no excessive idling, no repair ,except for 2 news tires and an wheel alignment and state inspection .
Car sounds the same, runs the same.No check engine light.
I changed the air filter , but no tune-up was performed.
Should I do basic tune-up ,wires,rotor+cap,sparkplugs ,possibly a fuel filter or take it to the mechanic to check the sudden drop in mpg. Could worn parts that i’m planning to replace by doing tune up cause such fast drop in mpg? I follow MPG daily , as it is displayed as default on my dash.
Thank you for your help.