Just wondering if the cold air is killing my fuel mileage. I am currently in Northern Tennessee visiting family and it was darn cold on the ride down from New Jersey. Air temp dropped down to 6 degrees on the ride down and fuel mileage was at 14.3mpg. I do not have a winter cover on the front of the truck so this is what I was thinking

Since I'm running unloaded, the turbo is not really working hard, so the air coming out of the turbo should not be that hot. So if it goes through the cooler and the air through the cooler is 6 degrees @ 70mph, that makes for some cold air going into the engine intake. Maybe too cold for good combustion.

Is it possible or am I nuts....

 

During the winter months, additives are often put into the fuel to keep it from gelling at cold temperatures. While the additives do this job really well, they also dilute the fuel somewhat, leading to less efficient combustion. You will see a noticeable improvement in fuel mileage in the coming months I'm sure.

 

Yes cold will affect fuel mileage by about 2-3 mpg. That and the fact you may have filled up in New Jersey with a winter blend fuel that also helps drop the mileage. Not sure if they use a winter blend in Tennessee.

 

Fuel additives like Howe's and power service wont hurt your mileage. #1 diesel absolutely kills your mileage.

For myself I run #2 diesel with Howe's, my mileage in the winter is off by maybe a .5 mpg. Winter blend you really never know what your getting conditioned fuel (good Deal)or #1-#2 blended fuel. (Bad deal)

I never run a winter front it seems to me the colder the better the power.

 

winter blend causes most diesels to lose 2-3 mpg. I think the diesels also probably lose a bit in extreme temperatures just trying to warm up. Fuel economy appears more related to winter diesel blends though.

 

I dont run a cold front either. Most of my driving is highway so the truck warms up fairly quickly. Even in our subzero Colorado winters.

 

I run the control panel at a major refinery. We make diesel in my unit along with other fuels. Our winter diesel blend is mainly Light Distillate and Heavy Naptha (like Kerosene) with a little Heavy Distillate. Summer blends are a little Light Distillate and lots of Heavy Distillate. The heavier constituants have highter BTU value per unit volume. Hence the much improved power and mileage you see in summer diesel. That's got more to do with mileage than the cold temps once your rig is at opperating temps.

cheers

 

We have two diesels, my truck and the wife's Jeep. Winter fuel #1 diesel reduces mpg about 2. The truck at -30 C sees a drop of about 3
to 4 mpg beyond that. The Jeep was getting 25 to 26 mpg in town. With winter fuel at -30 it gets 16 to 18.
But then one should check the mileage on a gas pot at -30. Our Cherokee with a 4.0 L 6 cylinder is lucky to get 15. The 5.9 L Grand that I had prior to the truck purchase - well we don't want to think about that let alone talk about it. Fun to drive though.

 

On average I lose about 3-4 mpg in winter. I read that its the combination of fuel, warm up time and on the highway, the colder, denser air is harder to move through. Plus at -30, everything is so friggin stiff, it takes power to move.

 

Cold air kills mileage. Its not that the intake air temp is cold, it that the dense air is harder to push thru. I recently drove to AZ from ID, and as the air temp increased so did my mileage, even on the same tank of fuel.

The winter front isn't needed at hwy speeds, the intake air gets too hot at 75-80 even in sub 10* weather. Also the IAT temps don't get that cold. In summer my IAT is about 8-10 above ambient, but on super cold days its about 15-20* warmer. Not sure why, but it works that way. With cold air you actually get more O2 per cycle, thus can make more hp on the same amount of air.

You also have to consider the tires are colder, so rolling resistance increases, trans/xcase/diffs are cooler, thus more resistance... and the fact that #1 has fewer BTU's all add up to a decrease in mileage.

 

I have an 08 dually with winter front. I just recently changed the air filter, fuel filter and cleaned the MAP sensor. Now, take this what it is worth, my overhead gave me 18 mpg (US) at 100 kph (62 mph). I know, I know, but my overhead has been fairly accurate and most importantly the improve economy was compared to the overhead. So there was a distinct improvement as I am using the same measuring device! The outside temp was about -5 C