Hello all, I have a new to me 2009 Expedition SSV with the tow package that used to be with my county's prosecutor office. It's got 134k on it now, and besides an oil change, reconnecting the factory horn, and installing a new head unit and backup camera since mine didn't have one factory, I haven't done anything to it, it's been running and driving as-is.
But I'm catching on that I'm getting absolutely terrible MPG on it. Since last fill-up I've only gone just about 100 miles and I'm down to half a tank. I initially suspected that the gauge was wrong but filling in between 1/4 and 1/2 gave me 12-ish gallons which seems right for a 28 gallon tank. It's not really running abnormally, maybe a tad sluggish but I'm coming from a 2001 Crown Vic which is lighter so I don't expect it to be nearly as fast off the line. As I said, I haven't done any maintenance yet besides an oil change, but I'm planning to do...
- Coolant Flush with new t-stat and maybe new crossover gaskets for safety.
- Trans pan drop and refill, putting a Dorman pan on in the meantime to make future service easier. And at the recommendation of some fine folks at the CV discord I'm on, replacing the stock trans cooler lines up front with regular 1/2" clamped oil hose since the stock ones can blow off apparently
- Both differentials, gear oil change
- Transfer Case fluid
- Air Filter though my current one looks newer
- Spark plugs, idk if they've ever been done, I have no maintenance records on this car.
- Throttle body cleaning
- Coil packs? I did them all OEM on my 01 CV because I kept having untraceable performance problems and it helped.
- Vacuum leak test? My PCV hose is pretty rotted, but that's the only one I've spotted so far
- EGR cleaning? My 01 Vic absolutely trashed the EGR system because of the huge amount of oil it was burning, but as far as I can tell this truck doesn't burn any.
Besides regular maintenance, is there anything else I should be looking at here? Fwiw I have ran a bottle of techron through the tank, didn't seem to do anything. Two things I can think of that might affect MPG are the t-stat being stuck open, it takes a long time to reach full temp *if* it reaches full temp, it's usually hovering around 150-170. Also it only happened once but I popped a circuit code for both upstream O2 sensors suddenly, and when I did some digging on Alldata I found a TSB that says basically to update the PCM software, so clearly my truck is missing this update. Can I do that myself, does it even affect MPG? Despite the truck running good something is clearly wrong with getting between 5-7 MPG by my math...
But I'm catching on that I'm getting absolutely terrible MPG on it. Since last fill-up I've only gone just about 100 miles and I'm down to half a tank. I initially suspected that the gauge was wrong but filling in between 1/4 and 1/2 gave me 12-ish gallons which seems right for a 28 gallon tank. It's not really running abnormally, maybe a tad sluggish but I'm coming from a 2001 Crown Vic which is lighter so I don't expect it to be nearly as fast off the line. As I said, I haven't done any maintenance yet besides an oil change, but I'm planning to do...
- Coolant Flush with new t-stat and maybe new crossover gaskets for safety.
- Trans pan drop and refill, putting a Dorman pan on in the meantime to make future service easier. And at the recommendation of some fine folks at the CV discord I'm on, replacing the stock trans cooler lines up front with regular 1/2" clamped oil hose since the stock ones can blow off apparently
- Both differentials, gear oil change
- Transfer Case fluid
- Air Filter though my current one looks newer
- Spark plugs, idk if they've ever been done, I have no maintenance records on this car.
- Throttle body cleaning
- Coil packs? I did them all OEM on my 01 CV because I kept having untraceable performance problems and it helped.
- Vacuum leak test? My PCV hose is pretty rotted, but that's the only one I've spotted so far
- EGR cleaning? My 01 Vic absolutely trashed the EGR system because of the huge amount of oil it was burning, but as far as I can tell this truck doesn't burn any.
Besides regular maintenance, is there anything else I should be looking at here? Fwiw I have ran a bottle of techron through the tank, didn't seem to do anything. Two things I can think of that might affect MPG are the t-stat being stuck open, it takes a long time to reach full temp *if* it reaches full temp, it's usually hovering around 150-170. Also it only happened once but I popped a circuit code for both upstream O2 sensors suddenly, and when I did some digging on Alldata I found a TSB that says basically to update the PCM software, so clearly my truck is missing this update. Can I do that myself, does it even affect MPG? Despite the truck running good something is clearly wrong with getting between 5-7 MPG by my math...
