MPG Loss

[JJC]

I recently drove back to Colorado from Texas, about an 18hr drive. I started out at 26.5 mpg then slowly declined to 22 mpg over the course of the trip. At home I cleaned the EGR tube which was not what I thought very dirty then cleaned the MAP sensor which was plugged. neither of these helped. Any suggestions?

 

[Polymers]

Depending on what part of Texas you started in, you were driving up hill most of the way. Not trying to be a smart a$$ but same thing happened to me the last time I drove from central TX to Denver area.

 

[fmatiella]

I recently drove back to Colorado from Texas, about an 18hr drive. I started out at 26.5 mpg then slowly declined to 22 mpg over the course of the trip. At home I cleaned the EGR tube which was not what I thought very dirty then cleaned the MAP sensor which was plugged. neither of these helped. Any suggestions?

How are you checking your MPG? On a recent trip to Frankenmuth, Michigan, I clocked 27.2 MPG going and 27 MPH coming back. I was elated. It took 24 gallons. But that did not sound right. 27 x 25 is 675 miles. But I drove only 570. If you divide 570 miles by 25 gallons you get 22.8. So I paid extra for a diesel engine because it is supposed to be economical but there are guys out there with the 5.7 hemi that are getting as much or better.
It is lways better to do the math by hand instead of trusting the on board computer. The milage per gallon figures printed on the sticker by Fiat Chrysler are bull shit. My calculations for city driving around town are down to 16.5 and not the 22 MPG that the computer gives you. My wife has a heavy foot. When she drives the RAM she gets 16 and 17 MPG on the computer. What would that be if I do the math myself, 12 or 13? Hell, my 97 Landrover Discovery with 200K on the clock gives me that, and it easier to park and drive around town. So what the hell did I pay $45k for a diesel hog?
Do the math by hand and then take a stiff shot of whiskey, you will need it.

I recently drove back to Colorado from Texas, about an 18hr drive. I started out at 26.5 mpg then slowly declined to 22 mpg over the course of the trip. At home I cleaned the EGR tube which was not what I thought very dirty then cleaned the MAP sensor which was plugged. neither of these helped. Any suggestions?

 

[JJC]

How are you checking your MPG? On a recent trip to Frankenmuth, Michigan, I clocked 27.2 MPG going and 27 MPH coming back. I was elated. It took 24 gallons. But that did not sound right. 27 x 25 is 675 miles. But I drove only 570. If you divide 570 miles by 25 gallons you get 22.8. So I paid extra for a diesel engine because it is supposed to be economical but there are guys out there with the 5.7 hemi that are getting as much or better.
It is lways better to do the math by hand instead of trusting the on board computer. The milage per gallon figures printed on the sticker by Fiat Chrysler are bull shit. My calculations for city driving around town are down to 16.5 and not the 22 MPG that the computer gives you. My wife has a heavy foot. When she drives the RAM she gets 16 and 17 MPG on the computer. What would that be if I do the math myself, 12 or 13? Hell, my 97 Landrover Discovery with 200K on the clock gives me that, and it easier to park and drive around town. So what the hell did I pay $45k for a diesel hog?
Do the math by hand and then take a stiff shot of whiskey, you will need it.

First, thanks for the reply. I intend to do as you have suggested but I must first head to the liquor store.

 

[Augiedoggy]

Are you trucks both stock as far as height and tire size? do you have heavy aggressive 10 ply tires vs the lighter 4 ply tires the trucks were rated and came with?

I drove my truck around for just over 2 months after I bought it without modifying the previous owners modifications. He had lowered the truck 2 inches in the front and 4 in the rear and the dealer I assume had put stock 2018 style aluminum rims with 265/70/17 (31.5") 4 ply 41lb tires. My truck is a crew cab tradesman with the longer 6.4 bed and it is 4wd. I averaged 24mpg overall and on the highway I got 34mpg! yes the truck is deleted and tuned. Once I lifted the truck with bilsein 5100s leveling struts and only lifed it 3" over stock in the front and 2" in the rear, I installed some used 18" rims with used mickey Thompson 10ply hybrid tires thats are 295/70/18 (34") my mileage went right down the toilet. I now get 15.9mpg overall and im lucky to hit 24mpg on the highway if the wind is blowing right. (speedometer is corrected and I have 3.92 gears.)

The other thing to mention is Ive heard it mentioned numerous times that not all diesel fuel is created equal. (especially during winter months)

 

[JJC]

Are you trucks both stock as far as height and tire size? do you have heavy aggressive 10 ply tires vs the lighter 4 ply tires the trucks were rated and came with?

I drove my truck around for just over 2 months after I bought it without modifying the previous owners modifications. He had lowered the truck 2 inches in the front and 4 in the rear and the dealer I assume had put stock 2018 style aluminum rims with 265/70/17 (31.5") 4 ply 41lb tires. My truck is a crew cab tradesman with the longer 6.4 bed and it is 4wd. I averaged 24mpg overall and on the highway I got 34mpg! yes the truck is deleted and tuned. Once I lifted the truck with bilsein 5100s leveling struts and only lifed it 3" over stock in the front and 2" in the rear, I installed some used 18" rims with used mickey Thompson 10ply hybrid tires thats are 295/70/18 (34") my mileage went right down the toilet. I now get 15.9mpg overall and im lucky to hit 24mpg on the highway if the wind is blowing right. (speedometer is corrected and I have 3.92 gears.)

The other thing to mention is Ive heard it mentioned numerous times that not all diesel fuel is created equal. (especially during winter months)

My truck is all stock but thanks for the info.

 

[EcoDiesel USA]

Texas to colorado is 100% uphill. Amarillo itself is 4000' above sea level.