Poor fuel mileage and very sooty tailpipe

Based on these two things, I will assume I am running rich. My 2013 Limited 4L is not throwing any codes, IE, the check engine light is not on. My mileage is 17 Miles per US Gal (14L/100km). with mostly highway driving. I think that should be 20 and 12 respectively.
From the google searches that I've done, the major causes of running rich are MAF sensor, O2 sensor and/or MAP sensor. Is there anything I'm missing? Because the truck is 9 years old and has over 200,000 km /120k miles on it, does it make sense to just replace all the sensors? Do they degrade gradually over time even though they are still operating within the parameters... possibly. What are your thoughts and or experiences? Thanks

 

Watching

 

17mpg at 70mph unloaded is about right for a stock truck.

 

Fuel trims will tell you if there is a problem

 

Mine does 20 to 21 under those conditions.

 

I guess full stock (im 2in lift, 265/75R16 lighter tires which is mostly stock) that sounds about right.

Much above 65mph though these trucks brick aerodynamics suck.

 

Moreso if you have a lift or "level". There is an aerodynamic reason for the slight rake. And it is, IMO, also the best look.

 

It certainly sounds like you're running rich. Just because the MIL hasn't been set doesn't mean there aren't one or more pending codes. You need a scan tool with live data capability so that you can view your fuel trims in real time; assuming they're going to be totally out of whack, you then need to work on why. Any, some, or all of the sensors mentioned could be a culprit, but with no MIL, it's unlikely as circuit high/low/out of range errors will normally set the MIL almost immediately (one or two trip detection logic).

DO NOT just fire the parts cannon - you could have an 02 sensor that isn't working, but it might not be the sensor, it could be a broken wire in a harness five feet away. You could replace 02 sensors all day and not solve the problem. You will likely need to have some basic trouble-shooting skills, wiring diagrams, a good DVOM and scan tool to sort this out.

 

Depending on your driving style that isn't too far off. My 2007 DC 4X4 is usually somewhere between 18-19 mpg for road trips. Around 16-17 for my normal everyday driving. I've hit 20 mpg a few times under ideal conditions. That is keeping speeds UNDER 70 mph. 70 mph seems to be the threshold. Above that and fuel mileage goes down fast, 15-16 mpg at 75 mph. I've had a couple of tanks since buying the truck where I hit 22 mpg. But that was on 2 lane roads were the typical speeds were around 50-55 mph with no stops or slowdowns.

 

What tester do I need for that?

 

My tester does not show any codes or problems. A green light was lite.

 

A scan tool that can display live data, fuel trims ideally shouldn't be more than +/-10% total trim (long term+short term) on both banks.
Have you ever changed your spark plugs? If not you are about 90k overdue.

 

Any tool that can look at generic OBD2 data

 

Thanks. The plugs were changed last year and the injectors were cleaned. I will have to buy a live scan tester however. Is there a brand that is recommended?

I have an OBD2 scanner but it does not test live data as far as I can tell.

 

My tester is the Innova 3100 abs. It shows all good. No fuel trims shown.

 

The data info isn't a pass or fail type of thing. You're looking for live data on the screen while driving down the road. Coolant temp, calculated load, engine rpm, etc

Might need a different tool

 

Is this vehicle bone stock right down to the tire sizes?

 

Lifted 2 inches and tires are 32"

 

Oh yeah, perfectly normal MPG's with that.

 

My thoughts? That's just about right. What make you think it's running rich? Soot in the tailpipe is normal it's the coldest part of the exhaust system. My 2011 had a O2 sensor fail at about 80K they don't go half bad. My manual trans 4L truck will do 20 at reasonable speeds but that's about it.