I have changed my oil,fuel filter,air filter and with the XZT my milage went form 17-19 normal everydad trips to the farm to now 15 mpg no matter how I drive it. The first few tanks I thought that it must be me keeping my foot in it more. This last tank was essentually all hwy and no more than 74mph and mostly at 64mph. 15.1 mpg . Any ideas? I wouldn't think that it's the module since it gave me 2-3 mpg's as soon as it was plugged in. Any help would be greatly appreciated.

 

My fuel miliage stinks to. I went from a 05 2500 6speed to a 06 3500 dually auto both 373 gear. I got around 19 in my 05 and under 15 in my 06. The auto is my problem I think.

 

I have the '06 dually and last trip from Houston to Port Fourchon, LA ( 397 miles) one way was 19.7 avg. both on my overhead and calculated at pump. Cruise on 70 mph and interstate 70% of way. Just got over 11k miles and burning strictly ULSD. Have you reset your overhead or are you calculating mileage?

 

Have you gone to taller tires?

 

Wind recently has been a killer..and my mileage has dropped because of it IMO. yesterday alone my outerwear on my air filter turned brown from the dust storm! No it wasn't dusty here in college station but i was in cedar hill yesterday around noon.

checked tire pressures? changed fuel stations recently? has the same fuel station changed to USLD? did they get a bad batch of diesel?

I swear it helps to run the dog snot out of your truck occasionally or go tow aggressively for a little bit too....carbon can build up putting around.

too many factors to really say...keep an eye on it and see if it progresses or not...

 

There can be a wide variance in fuel consumption between these speed ranges. Assuming everything else you do is consistent/regularly maintained and you hand calculate the MPG the amount of time you spend at what speed is the only thing I can think of that would cause the change. Of course there are so many things to consider here, that's just another one. The drop isn't too large to cause concern, so give it some time. How many miles are on this truck. I noticed improvement upwards of 15K miles. Running any additives and are you fueling at the same place everytime?

 

Was the oil, fuel filter, and air changed recently?? The reason I asked is because if you like most of us and pull of the air box tube to the turbo to change the oil filter, you might have a boost leak. I had the same problem on my '01. I just got down changing all the filters and driving for a couple of tanks on the highway which I was getting 15-16 with normally 19-21. I forgot to tighten up the clamps. Just a suggestion.

 

I recently took a small road trip and I took my Dodge (Usually when I don't pull anything I take the Ford ) Anyways I filled up and never drove over 60 and after 320 miles it took 16.1 gallons which is 19.875 Then I got on interstate and drove 70-75 all the way home and I got 14.6

 

That's odd, I would have had my better mileage at the higher speeds.

 

My mileage recently dropped from a steady 21mpg on the highway to 16 mpg. I changed my oil/filter, cleaned the intake and installed a new fuel filter. No improvement. Drove to Quadzilla in Ft. Worth...turns out my XZT wasn't working. They immediately replaced it, mileage back up to 21mpg again.

 

Winter blend of diesel always causes a drop in mileage on the trucks I have owned. That combined with the LSD or ULSD are probably what's causing your issues. It should get better when we are back to summer blend...

 

I believe that Ill have to pay QUAD a visit. When i first installed the XZT my mileage shot up 2-3 mpg's (always hand calculated). I checked my air filter again and I get Diesel at the same pump all the time. This mileage is about the same that I was getting prior to the XZT so maybe it has something to do with it. I don't have a loss of power though so maybe not. I have noticed a sound underhood today that I would consider a injector knock under medium acceleration.

 

I hate to be a pest but I changed from a stock 265 to a 315/70/17 and would like to know how to do a conversion from miles shown on tripometer to actual miles traveled. Anyone know how to convert this. I know my mileage dropped but I can't seem to get anymore than 400-450 miles per tank. 35 gallons. somewhere around 13mpg. I rarely do any highway driving, mainly back roads and state highways. Rarely ever on the parkway or interstate.

 

I bet its the ULSD. I hate it with a passion.

 

I did go up in size to 285/70/17 but this was awhile back and they didn't affect the mpg's at all.