Bad gas mileage

[koda2000]

Yes, O2 sensors can have an adverse effect on fuel economy, so can a bad bad coolant temp sensor or bad thermostat, just to name a few things.

When I first bought our '00 Mountaineer 5.0L it was getting 13 MPG highway on the drive home, driving 60 on flat terrain. The coolant temp gauge was barely above cold. i replaced the thermostat and the highway MPG went from 13 to 22. O2 sensor issues can cause similar problems and don't always throw DTC's.

We're still waiting on the OP to tell us exactly what "bad gas mileage" is.

 

[DJ Al]

Lots of factors affecting mileage on your 01 sport trac.
Tire pressure, where you get gas...yes, some places have an unacceptable amount of water and that is not good.. How old are your ignition items, plugs, wires and coil pack. Dirty injectors make your performance and milege suck. How long has it been since your
gaskets (intake and throttle body) been changed? Gaskets get brittle, cracked and start leaking. Have you checked your vacuum lines. egr, other air affected devices. Cleaning the contacts on the computer and the cube with contact cleaner or deoxit helps to improve performance. Brakes and differential may need looked at too. Last week, I replaced injectors, plugs, wires, coil pack, vacuum tubes and gaskets on throttle body and lower manifold and WOW! Totally different car. So far, mileage is checking in about
19 mpg hiway and 15 town..Lots of work but you can achieve your goal of having a better running truck..good luck!

 

[donalds]

Last week, I replaced injectors, plugs, wires, coil pack, vacuum tubes and gaskets on throttle body and lower manifold and WOW! Totally different car

Why injectors?

 

[koda2000]

Lots of factors affecting mileage on your 01 sport trac.
Tire pressure, where you get gas...yes, some places have an unacceptable amount of water and that is not good.. How old are your ignition items, plugs, wires and coil pack. Dirty injectors make your performance and milege suck. How long has it been since your
gaskets (intake and throttle body) been changed? Gaskets get brittle, cracked and start leaking. Have you checked your vacuum lines. egr, other air affected devices. Cleaning the contacts on the computer and the cube with contact cleaner or deoxit helps to improve performance. Brakes and differential may need looked at too. Last week, I replaced injectors, plugs, wires, coil pack, vacuum tubes and gaskets on throttle body and lower manifold and WOW! Totally different car. So far, mileage is checking in about
19 mpg hiway and 15 town..Lots of work but you can achieve your goal of having a better running truck..good luck!

Phew, talk about firing the parts cannon.

 

[donalds]