Went from 21-22mpg @65-70mph down to 14-16mpg. My fuel filter has about 3k miles and my K&N filter has about 7k miles on it. Someone suggested my EGR Blocker plate is leaking. I don't tow/haul anything and driven about 20 miles a week. Your thoughts???

Leaving 4hi on by accident will do that... I learned that the hard way. I was pulling a bass boat down the expressway, and was averaging 14mpg. I was a little disappointed in what I was seeing. It wasn't until I was backing the boat into the driveway and heard the front end clunk that I looked over to see the tiny 4hi indicator light was on. It all started making sense.... I doubt this is the problem with your truck, but it's possible.

its cold now do you idle it for a while before you leave?

Winter fuel is blended and does not run as effiecent..g

Winter fuel is blended and does not run as effiecent..g
x2

You running the winter cover?

This cold can kill mpg along with winter blend.

winter blend fuel- i lose a solid 1.5mpg.

Yes, I put the winter cover on when it was in the low 30's. Programmed High Idle at same time. I drove it today 65mph, granted temp was only -1 degrees, 13.9mpg (computer reading). Should I not expect any better than that with these temps?

Yes, please do tell. I am about to go to Chicago for two weeks and if my MPG drops like that....I'll know why.

Hey jdiesel, bet u don't have to worry -1 degrees where ur at. Thinking about moving to Greenville area for that reason.

You are correct SIR....the coldest I have seen in my 15 yrs down here is 10 F

could of gotten some bad fuel and clogged your filter, try changing your fuel filter

Much of the problems is the winter fuel, and letting it idle more etc.. I drop from 17-18's to 14-15 every winter. Seems to start early November and ends may of so...

I got a whopping 12mpg.....But the tank lasted 6 weeks so im not mad. Lasts that long when your drive to work is only 3mi each way. Sits running to warm up longer than it takes to drive to work.

Its just winter. You're using winter blend fuel, running your front cover, and it takes longer for your truck to warm up while driving (so you're using more fuel until its warmed up). Your MPGs are right in line with what I'm experiencing here in SE Minnesota.

I get about 15 MPG on mine during the winter also. Seems to be normal.

It would be interesting to see if CNG helps out at all in the winter.

Winter blend. Every fall, I drop from 15.5 mpg to just under 12.5 mpg. It's almost an exact science to how much and when it drops. Come spring, it'll be wwwwaaaayyy back up there around 15.5 mpg again.

Yup it is winter but it seems this winter is worse.

With this crappy winter fuel and stanadyne every tank, im getting 13.7mpg on dic. In summer with #2 diesel i get 17-18, winter just kills these trucks mileage, at least mine.:eek:

Its terrible that these high tech modern day diesels are getting such shitty mileage, these engines dont even work hard pulling these trucks around, damp a tractor trailer hauling 40k lbs around and shaped like a giant billboard does 8mpg, to me it makes no sence at all

Well, it sounds like I'm not the only one dropping mpg's. I appreciate all the info on this thread. The feedback has been great. Didn't realize the cold could do that and the winterblend fuel. Was worried I may have had other issues.

sounds like winter fuel to me as well. mine dropped about 2 mpg with treated fuel and me adding in additional.

Big rigs dont get 8mpg. They get about half of that around 4mpg.

Release the parking brake.

J/K - I didn't get the winter covers with mine. I drop some cardboard in front of the rad - speeds up warmup, and seems to improve mileage about .5-1 MPG

Cheap and easy. Just don't forget to take it out before towing heavy or when the temps rise, or you will be MFing the truck until you remember. Don't ask how I know this one.

I just completed a trip from Kansas to CA, Up until AZ i was doing 17-19mpg hand calcd, doing ~75mph on highway 40 temps were from the 20's to the 40's. Including 2hrs of idling while sleeping in the truck.

From AZ to CA I saw 20-23mpg hand calcd temps were in the 70's avg speed was ~70mph

I do believe it is a combination of the higher temps and maybe a different fuel mixture?

I just completed a trip from Kansas to CA, Up until AZ i was doing 17-19mpg hand calcd, doing ~75mph on highway 40 temps were from the 20's to the 40's. Including 2hrs of idling while sleeping in the truck.

From AZ to CA I saw 20-23mpg hand calcd temps were in the 70's avg speed was ~70mph

I do believe it is a combination of the higher temps and maybe a different fuel mixture?


Are you stock?

Went from 21-22mpg @65-70mph down to 14-16mpg. My fuel filter has about 3k miles and my K&N filter has about 7k miles on it. Someone suggested my EGR Blocker plate is leaking. I don't tow/haul anything and driven about 20 miles a week. Your thoughts???

If your only driving 20 miles a week, your probably spending more idle (warm up) time than driving which will kill your fuel mileage. Short trips will have ill effects on your diesel in many ways.

Jason

I drop anywhere from 3 to 4 mpg in the winter seems the colder it gets the worse also from one fuel station to the next I can get different mpg even in the summer

Its terrible that these high tech modern day diesels are getting such shitty mileage, these engines dont even work hard pulling these trucks around, damp a tractor trailer hauling 40k lbs around and shaped like a giant billboard does 8mpg, to me it makes no sence at all
I 2nd that even the small cars get the same mpg in gas or diesel something is not right I think the oil companys have a say in car mfg

I don't know guys he is talking 5-7 mpg not 1 or 2. Could be something else. I live in Central Oregon and it gets pretty cold here, been in the teens and low 20's seems like forever. Winter fuel does effect mine a bit but only a mile or two per gallon. My drive to Boise last week I still ave about 20 mph. I can get 22 normally. I don't run any winter cover, but it isn't -20 either.

The three mile trips have more to do with it than the winter blend fuel , especially in cold weather . That engine never reaches operating temperature , not to mention all the other gears.

Big rigs dont get 8mpg. They get about half of that around 4mpg. i have a 97 kenworth w900l daycab & haul 22ft dump trailor, i haul gravel,( lots of stop & go) it has 430-470hp detroit ,in the summer i always get @ least 6 mpg..used to get 6.5 till i installed a pittsburgh powerbox,i run an extra 100hp so it is 530 on the pedal -570 hp on the cruise. BUT, i have to drive it right to get this mpg.-but i dont baby it either.