I have a stock 2008 Ram 2500 with the 6.7L Cummins that has gradually lost MPG as I put more miles on it. I currently have 82K on it and have kept it regularly maintained at the dealer. It seemed that on the hwy I used to get 20/21 mpg and towing my 9000lb travel trailer I would get 12/13 mpg. I run at 1800 rpms which is equivalent to 75-79mph on the hwy or 65-69 mph when towing.

Lately, I have seen the mpg slide to 17/18 mpg on the hwy and last week I towed my trailer and only got 9/10 mpg. Still running at the same rpms as well.

I have only had regular oil and filter changes, but I did have the turbo replaced under warranty about 10K ago. Still seem to have just as much power as usual to climb a hill if needed.

Any thoughts of what could be dragging it down?

 

probably the wounderful exhaust filter/cat clogging up, the filter will only go so long before it needs to be removed and cleaned or replaced

 

If that is the CCV filter that gets changed at 70K. I have changed that one. Is this what you are referring to?

 

He is referring to the DPF, diesel particulate filter, in the exhaust. I'm going to go along with things clogging up; the soot will build up in the intake manifold itself, there is nothing that will burn this up and clean it out.

Here is the intake heater grid on the 6.7 I put in my 03, this is about 107k miles.





This crap just builds up and builds up, taking just a bit more room and restricting airflow just a little bit, after a while that little bit is a fair amount.

Also, on the DPF, when it regenerates, there is ash left over. The ash doesn't burn, so it builds up in the DPF and needs to be cleaned out.

You have two options, 1) take it to Fremont (I see you're in Casper) and have them clean the DPF out, or 2) you can do deletes if you are so inclined. This will void your warranty, but you'll never have issues with those parts again.

 

First off, do a DPF and EGR delete with a tuner, you'll thank me after

Second. Do you run any additive in your fuel? How often do you change your fuel filter?

 

Good luck finding a tuner.

2nd gen Ram Cummins and 3rd gen Ram Cummins CR FTW!

 

I add an additive on every other tank of fuel.

 

What do you add?

And why would you want to waste money on them?

 

Good thing on the additive. Definitely change that fuel filter every oil change