Forum Discussion

Explorer

Mar 18, 2015

6.7 Cummins Non DEF vs Newer DEF Trucks

Hi, I used to have a 2008 6.7 CTD 4x4 which towed great but the fuel economy sucked and I know many folks had issues with the first era of emmissions "bluetec" trucks. Last week I picked up a new 2014 CTD with the DEF setup. My question is what major changes did they do to these trucks to supposedly improve fuel economy? I'm assuming it still has a DPF but is it a more free breathing DPF and exhaust system? The reason I ask is because I think this newer truck is louder and sounds meaner than my 2008 plus it seems to do better on fuel so far. I also notice I can almost swear you can kind of hear the turbo with it idling like the old 5.9s. I've driven about 400 miles and the MPG computer is already averaging 16.7 mpg. I know these newer trucks are mostly geared with 3.42's with the exception of the duallies maybe but I'm just wondering what major changes the exhaust system experienced besides the DEL system?

Tow Vehicles

64 Replies

donn0128
Explorer II
Mar 18, 2015
More emission junk choking more from your dollar. My 07 6.7L is just fine. Fuel economy is IMHO great for what it is! I did not buy it for great economy, I bought it to tow a large fifth wheel.
ramgunner
Explorer
Mar 18, 2015
In our 2014 we see a regen about every 800 to 1000 miles (mix of freeway and stop-and-go city streets). We haven't had any issues with the system.
Bedlam
Moderator
Mar 18, 2015
In the past, combustion temperatures had to kept down to prevent tailpipe emissions which resulted in more soot buildup in the DPF and more regens. In current models, the exhaust is treated with DEF and allows for higher temperatures which reduces soot and regens.
Grit_dog
Navigator II
Mar 18, 2015
I believe the emissions is relatively the same with exception of the added DEF injection. This also adds an ammonia sensor which I don't think was on the pre def trucks.
The new trucks are noticeably louder and I have heard the turbo on occasion at idle.
As far as mileage goes, the trucks I'm around only get 3-4mpg due to a lot of idling.
The intake can definetly get loud in the cold with the active intake heat management when it switches to pulling hot air from underwood.