Poor Gas Mileage 2007 Sport Trac 4x4 4.6L V8

[TylerRed]

I have a 2007 Sport Trac with the 4.6L V8. I bought it with only 89000 miles on it and it was very well taken care of. I now have 95000 miles on her and she runs great. However, I have always gotten really poor gas mileage since I bought her. I travel very short distances and live in Florida where it is flat and I average around 10mpg and sometimes it drops to 8 or 9. I am not pulling any codes and am wondering what possibly could be giving me such bad gas mileage without any noticeable issues when driving her. I do get better MPG when driving longer distances, but we are talking maybe 12 in the city and 15 on the highway. I also do not drive it like a teenager. I just run up a mile and a half up to drop off and pick up my son from school. Please help. I don't want to just start throwing money at the problem buying coils and spark plugs if that is not the issue.

 

[Bazz270]

first try motorcraft spark plugs and air filter change (the OEM ones are cheap)

 

[94Eddie]

If you are driving short distances where the engine is not getting up to operating temperature then your gas mileage will be very low. IMO, if there was a problem then it would trip some codes due to the engine running rich. This is why I think the low mpg for city driving is due to the short trips where the engine is not getting up to operating temperature. I have the same drive train as you and I get around 20 mpg on the highway doing 60-65 mph on flat ground. At 75-80 I get around 17-18 mpg. Your highway mpg seems low but the differences could be due to you having a Sport Trac that might be less aerodynamic. The EPA numbers for your vehicle are 13 city, 18 highway and 15 combined.

I think changing plugs would be worthwhile but I doubt it will make a huge difference in mpg. Keep in mind that the plugs you likely have are the two piece ones that have a tendency to break during extraction. You should follow the TSB procedure to remove them. You might want to check the catalytic convertors for excessive back pressure and clean the MAF sensor. It also wouldn't hurt to do a transmission pan drop, replace the filter and refill along with draining the transfer case and refilling.