Poor fuel mileage and very sooty tailpipe

https://m.youtube.com/watch?v=cARQ0jZZ4Qc
https://m.youtube.com/watch?v=5WnM_NsOtd8
Yesterday I ordered a new scan tool that has live data. It should arrive today. This morning I watched these two video's, which I found to be very good, and as soon as I get my scan tool and get some data, I will try to see what is going on. I understand that everything might come out to be normal and I'm fine with that but I still won't be happy unless I know for sure.

 

Youre lucky to be getting mileage that good imo

 

OP have you done basic maintenance tasks like cleaning the MAF sensor, throttle body, air filter, etc? If not, start there. Like others have said if you just throw parts at it blindly you could just be burning money.

I will also echo what others have said - 17mpg for your setup probably isn't far off what it should be. I have a similar setup and I can still get 20-21 but it depends on driving style, speed (can confirm the 70MPH claim that mpg drops off sharply), tire pressures, and I find ambient temperature along with A/C usage also has certain effects. I will also stress that tire pressures sometimes have a larger effect than most people think about and it's one of the easiest factors.

 

I purchased my 2010 in Nov 2016 and it is stock mechanically.
To date my mileage has been:


The 9.3 was during a cold spell one winter driving it back and forth to work in stop-and-go traffic in four-wheel drive. It's not hard to get in the 10s in the winter when you have a week of sub-zero (F) days.

The 23.9 was accomplished during the warmer months traveling about 60/65 mph and I only got 23 plus twice—both on long trips where I used nearly the entire tank. The speed limit on those roads is 55 and 60 mph and no one does it, not even the patrol cars. City and I imagine trail driving just kills mpg.

The lifetime average has crept up a bit since I retired and don't do nearly the amount of stop and go. My current five-month average is just over 20.

 

I do regular basic maintenance. Plugs have been changed. Injectors have been cleaned, coolant flushed, air filter changed regular, of course oil changes. I have not cleaned the MAF. I didn't know that was a thing. I drive like an old person so I thought My mileage should be a bit better.

 

I got my new scanner today. Going to give it a go.