Hello friends, I am currently running into very very poor mileage while towing. Truck is the 03 in my sig below. Pulling a 53ft wedge loaded ~12k. I used to get 9-11mpg depending on wind loaded, and 12-15mpg when the trailer was empty. The past few times I have pulled, mileage has significantly decreased to low 7's even in the 6's. There have been some other things I have noticed while driving empty (no trailer at all) such as the truck feels like it doesn't have consistent power throughout the rpm range, and it just feels like an anchor. I don't have the EZ connected at all, and I should add that the injectors are only about ~30k old. They are slightly larger than stock, but very little. Installing these did decrease the mileage initially, but not more than a .5-1 mpg total difference. I run power service additive regularly, and nothing else (that I have noticed) has changed.

 

It could be from the Winter fuel that always lowers our fuel mileage this time of year.

 

It makes that big of a difference huh? I thought that it would, just not that much. Does make sense though, as it did get cold out around the same time the poor mileage started.

 

Just the cold alone can lowered my mpg by 1-2 mpg and we had not gone below 20 degrees at night. Once it gets colder at night I see my over all mpg drop down to between 12-15 mpg from my normal 17-19 mpg in the warmer weather.

 

I should point out that I've recently set p0234, and I notice at night when a car is behind me, I can see a significant amount of smoke billowing out under normal driving. I don't recall this happening before, and it seems to smoke a bit at idle if it is idling for ~30 minutes or more.

 

same problem here. started smoking a little a idle and then under normal driving conditions. need valve adjustment ???? injector problems ???

just rolled over a 100,000......

 

Hey 2tone12valve, we're pratically neighbors. I live in Warsaw.

My truck has dropped 2 mpg in the last month since it's been cold outside.
It sounds like an injector issue if the trucks putting out smoke like that.

just curious, what do you haul that puts all those miles on your trucks?

 

I typically haul enclosed cargo trailers regionally, then bring 2-3 cars back towards home.

 

I normally see a drop of about 2 MPG for the winter fuel. Do you have any guages? Could check to see if your truck is making full boost....

And with the 03 do you really have the G-56 trans?

 

is winter fuel nation wide, or just in cold region?

 

Not sure on the G56 trans, I share this computer with my dad, perhaps that is his assumption

 

i lose a good 1.5mpg with winter blend fuel!

 

My truck has been doing the same thing. I have 43k and the other day, on the interstate under normal driving, my truck had a slight smoke haze to it. We are still using number 2 fuel. My truck was plugged in, temp was 13 degrees out, full bottle of Power Service in a full tank of fuel. It idle great, no hesitation, just smoked on the highway. Little haze. Never done this before. Whats up.

 

Just got home from a run, and I noticed that the truck not only has a "hanging rpm" between shifts, but it goes into high idle when I pull up to a toll booth, and will not come down by depressing the brake. These symptoms are all adding up to possibly FCA? It's been replaced before, but could have gone bad again.