Power wagon terrible mpg

[Grimlock]

Hello all, I am new to Ram ownership and this forum. I recently bought a 19 power wagon 27000 miles on it with 35s that I do really like but the mpg is appalling. Around town I can get in the mid teens but the average is much lower because anytime you get near the gas pedal it drops to like 6 so it destroys the average. This is all in a totally unloaded vehicle. I drive 20-30 minutes to and from work on open highway. At 70 and up steady state cruising on flat level road it says 10mpg. I’m getting about 270 miles per tank also. My driving is very normal and a good combination of town and highway.
I have been looking for answers on the forums etc and while there is a lot of discussion about the mileage no one seems to have any real answers. I see a lot of people saying they get mid or high teens on the highway, if that is true it’s really concerning. I know this truck has the MDS system but I can’t tell if it’s operating or not. I never hear or feel any change in the way it runs so maybe that is causing the mileage. There is no engine light or anything so seems unlikely there is an issue with that.
Any help or insights will be greatly appreciated.

 

[Crusty old shellback]

Do you know if the previous owner recalibrated for the larger tires?
I've got a 21 with 35s and recalibrated and get about 13 plus doing 70.

 

[Grimlock]

I have no idea but the miles per hour between gauge and my navigation is pretty close. Also the tire circumstance difference is less than 7% so wouldn’t the maximum discrepancy be .7 mpg per 10mpg? I am getting about 270 miles from a tank which comes out to 10.8 mpg so it seems accurate.

 

[Crusty old shellback]

Stock tires were 33"
So you went up 2".

Download a app for speed and see how it compares. It may be more accurate than a navigation system, unless you have a good one.
You can go into your settings and turn on the Echo mode. All that does is light a light to tell you when it's on. Even with the light not turned on, it still goes into MDS, you cant disable it.
Other than checking those things, I'm not sure.
I have 19K miles on mine and constantly see 13.
Maybe check actual mileage by gallons to miles traveled after filling up, rather than what the computer says.

 

[Grimlock]

I have eco on and see the light but haven't noticed any diff In mpg. Sound or feel when it's on. By the gauge I'm getting 270miles per tank . I don't know what else to do either. May find someone with the same truck and see if I can drive theirs.

 

[Crusty old shellback]

Yea, I can barley hear a difference when it goes into MDS mode. You have to really pay attention to it to hear it.

Try resetting your MPG and trip meter, then get on the highway and see what it reads.

 

[jadmt]

I have no idea but the miles per hour between gauge and my navigation is pretty close. Also the tire circumstance difference is less than 7% so wouldn’t the maximum discrepancy be .7 mpg per 10mpg? I am getting about 270 miles from a tank which comes out to 10.8 mpg so it seems accurate.

This basically 70 mph tankful. Normally what I get. Absolutely calibrate your speedometer. If I don't when I switch back and forth from stock to 35's I can tell a difference in shifting which would affect mpg. I run two sets of tires depends on what I am doing. On my 2020 I can not tell if mds is kicked in or not but eco light comes on under light load

 

[Grimlock]

I guess I will have to calibrate the speedo and see what happens. What is the recommended method of doing this?

 

[Grimlock]

Just occurred to me, I bought this truck used with 35s on it. Is there a way to tell if it’s already been calibrated?

 

[H3LZSN1P3R]

Just occurred to me, I bought this truck used with 35s on it. Is there a way to tell if it’s already been calibrated?

Gps or a GPS speedo app on your phone see if its the same as the speedo

 

[Crusty old shellback]

Make a mark on the tire and ground at normal operating presdure. Push the truck forward for one tire revolution.
Mark the ground. Measure the distance that it traveled. Convert to MM.
Use that number in AlphaOBD for tire circumfrence.
That's the most accurate way and what I used.

 

[Grimlock]

It’s close. I tried it at around 40 but I will do it again tomorrow at highway speed to see what the margin is