2017 Limited EL in tow haul runs rich?

[LDS777]

I have the HD tow package and just had a tune up, replaced 2 coil packs and fuel injector service. The first time I towed a 3,000 trailer I noticed black soot all over the tailpipe, and only got 10 mpg ; there was no check engine light. SUV runs good but runs rich in tow haul. What fuel mileage is expected in tow haul and why does it run rich? Everyday fuel mileage is approximately 18 mpg.

 

[JasonH]

The aero profile is the biggest factor for mpg. You said 3,000 lbs, but is it a parachute, or a brick? Might need to get the coolant bottle tested for combustion gases. When mine did that, I had a leaking head gasket. It was somewhat apparent because the exhaust stank and there was light white smoke. MPG towing varies widely, but I'm always below 10 mpg. However, I have a large camper.

 

[LDS777]

Thanks I will look into this. I am towing a v-nose motorcycle trailer which is butted up to the bumper. Took SUV into shop today and there were no codes stored. Shop said that the weight did not make a difference; it was still in tow haul and the computer compensates for the fuel and the turbos really kicking in on the hills but the unit pulled sweet and did not even know the trailer was there. I need to also take into account that traveling 70 mph on hilly mountainous highway did play a part in the lower fuel mileage as well but was mostly concerned with he black soot all over the tailpipe and hoping my injectors are not all carboned up again right after getting the fuel injector service done. However fuel mileage not towing is a decent 21-22 mph.

 

[07mustangman]

I have a 2017 Limited 4wd and I usually get 18 daily driving to work. I live in Tennessee and I pulled a 6x10 enclosed trailer to Florida for vacation and I usually drove around 75-80 and my mileage went to around 10. Pulled great though.