Drop in Mileage After Heavy Towing

[Doughboy21kd]

1st Read SIG. Now what my problem is:



I have about 14k on the truck now. I have had the truck since new. All this time i have been gettin anywhere from mid 13's to 15's MPG in town. I have towed with it off and on some heavy, some light, some extremely heavy... . This last wednesday I grossed 21,800lbs (truck, trailer, cargo) pulled it over to Montana so it went over a couple of mountain passes i took it up the passes at 55-60mph and my exhaust temps peaked about 1000-1100 post turbo. i averaged 12. 5-12. 8 towing that over and i also got that coming back empty, trailer weighs 4k empty. Now that i am runnin around town again no trailer my mileage has dropped to about 11. 9-12. 3 MPG. I am just tryin to figure it out... . ANY ideas would be helpful on what you think is wrong..... Its going to dealership Monday and they gonna go through the computer and see whats going on..... Its strange.



I was told and always thought that after the 1st 500 miles, drive it how you normally would to break in the motor and also have been told to put a load on it and make it WORK.....



So thats my problem any INSIGHT would be great...



THANKS IN ADVANCE

 

[steved]

Could be as simple as you got a bad tank of fuel. I have also seen them take a few days to reset the computer as it learns your driving habits (in your case towing heavy, dump more fuel)... so it might take a day or two of normal driving to reset it... my 99 was this way.



My 04 varies widely depending on the fuel... I don't tow heavy.



steved

 

[klenger]

Are you hand calculating the milage or reading it from the overhead computer? If it's from the overhead, you need to reset it to clear out the lower milage from towing.

 

[Doughboy21kd]

yeah its been reset and its been both hand calculated and overhead

 

[Doughboy21kd]

Also I have thought of a couple more things that might effect my mileage so tell me what you think. PLEASE



1. I added some of that HOWES Anti-gel Fuel forumla maybe I added to much.



2. Dodge says to change fuel filter in canister every 15k. I just pulled it out and it looks brand new. Maybe they always look brand new but still need changed before 15k.



3. When do you guys change your fuel filter?



Thats all that I came up with, so do you guys think that either of those would be a factor over one day?

 

[klenger]

I'm concerned about a fuel filter that's still brand new looking after 15K. Is there any way that fuel could be bypassing the filter if something is blocked?

 

[Doughboy21kd]

tell you what i'll go pull it and take a pic of it...

 

[MMeier]

15k, I say go ahead and change it regardless of what it looks like .

 

[Doughboy21kd]

Well I just confirmed it..... Went out and pulled to see what it looked like... And sure enough its a Mineral grey like the color of my truck... . I pulled it 2500 miles ago and it was white like it was BRAND NEW... . So i dont know... I went ahead a changed it so well see what happens..... THANKS Again guys

 

[KevinWatts]

Just as a side note. I'd be a little careful about doing heavy sustained pulls at 1100 deg POST turbo. If I'm not mistaken, that puts your pre turbo temp up around 1400 or so. Nothing to worrry about for a drag race, but too warm for a lengthy period.

 

[Dieselnerd]

With a stock engine the EGT's shouldn't be a concern. The old rules from 2nd gen days do not appy to the 3rd gens. The 3rd gens have hardened valve seats, special valve material (don't remember the name and too lazy to look it up) as well as much bigger oil cooling jets that spray the pistons. Another thing to keep in mind is the 3rd injection event which is meant to keep the exhaust hotter for the catalytic converter. This means your exhaust temp is higher but all that heat is not going into the pistons. If I remember right the 3rd gens can sustain 1600 degrees pre turbo with no meltdown.



If I read Doughboy's sig correctly, he is stock. My post turbo temps will also go over 1100 towing heavy up long hills. I'm stock, in stock configuration it's not a problem, modified you have to watch it since you can quickly exceed the stock limits. Not a good idea to monitor post turbo unless you are stock of course.