First Diesel

[MBaugh]

Hey out there. First time posting a question here. I picked up a new 2020 HD 2500 with the Cummins diesel in January. I need to know if my truck is using too much DEF. One of my coworkers has a 2018 and he says a tank of DEF lasts him about 7000 miles. I have gotten 2,878 miles from full to low DEF light. Is there a reason coworker is getting that much more? All opinions are welcome.

 

[carlrx7]

i average 700 miles per gallon of def. Your coworker is either lying or his wife fills it up for him.

 

[H3LZSN1P3R]

i average 700 miles per gallon of def. Your coworker is either lying or his wife fills it up for him.

No he would be accurate the 2018 was setup to regen as needed and used much less def the 2019+ was setup for auto regen on a periodic schedule so the dpf does not have a chance to get build up so it uses about 3 times the def as the older 4th gens

your 700mpg avg seems pretty far fetched as most see 450-550mpg avg of. Def on the 19+ cummins

 

[Xflight29]

My 16 used a tank of DEF every 6500 miles +/- .

 

[John Jensen]

No he would be accurate the 2018 was setup to regen as needed and used much less def the 2019+ was setup for active regen on a periodic schedule so the dpf does not have a chance to get build up so it uses about 3 times the def as the older 4th gens

your 700mpg avg seems pretty far fetched as most see 450-550mpg avg of. Def on the 19+ cummins

Yep! 2019+ are programmed differently than pre 2019. While I don't like the DEF usage rate I like the cleaner burning and the longer miles between active regens.

What I'm having trouble understanding is how the frequent DEF usage affects "the dpf so it does not have a chance to get build up". As I understand the system DEF is injected into SCR which is at the end of the exhaust. How does DEF prevent "build up" in the DPF which is at the front of the exhaust?

I didn't get 700 mpg as his average, I calculated it at 523 mpg which would put him in the correct usage zone. That's also about what I am getting on my 2020 HO.

 

[H3LZSN1P3R]

As I understand the system DEF is injected into SCR which is at the end of the exhaust. How does DEF prevent "build up" in the DPF which is at the front of the exhaust?

What i ment the automatic regen happens more often to prevent the soot buildup in the DPF using more DEF during that process.... not saying the DEF is cleaning the DPF.... its also my understanding these trucks run hotter contributing to the higher DEF usage

 

[John Jensen]

What i ment the automatic regen happens more often to prevent the soot buildup in the DPF using more DEF during that process.... not saying the DEF is cleaning the DPF.... its also my understanding these trucks run hotter contributing to the higher DEF usage

Thanks, that makes sense. I have a question about your use of the word Regen. I believe:

Active Regens take place when DPF soot level reaches 65-66%. Fuel is injected into the DPF to raise temps to perform the regen. No DEF is involved.

Passive Regens take place when the EGT's are hot enough (700+f). No extra fuel burned and DEf is not used

DEF is constantly injected into the SCR. I don't know what triggers it or determines the quantity. It is not a Regen, what is this process properly called?

 

[H3LZSN1P3R]

Thanks, that makes sense. I have a question about your use of the word Regen. I believe:

Active Regens take place when DPF soot level reaches 65-66%. Fuel is injected into the DPF to raise temps to perform the regen. No DEF is involved.

Passive Regens take place when the EGT's are hot enough (700+f). No extra fuel burned and DEf is not used

DEF is constantly injected into the SCR. I don't know what triggers it or determines the quantity. It is not a Regen, what is this process properly called?

Def works on exhaust temps mainly the more nox gas the more def needed to break it down so when the auto and active regens make the system run hotter more def is used to keep the nox from exiting the scr

 

[John Jensen]

Def works on exhaust temps mainly the more nox gas the more def needed to break it down so when the auto and active regens make the system run hotter more def is used to keep the nox from exiting the scr

Thanks,
So the NOX levels trigger the DEF injection and also determines the quantity. Makes sense.
And, the active and passive regens are not involved, they are merely exacerbating the NOX levels

 

[RVTRKN]

See the hand calculated numbers for the first 10K miles, I'll post the next 5K miles in a week or so. I'm currently just at 14,800 miles, so one more tank of both DEF and Fuel. Keep in mind, when towing heavy, you'll go through it faster. These averages are mostly empty but I have towed my heavy 5ver and lighter pontoon boat a few miles.

 

[MBaugh]

i average 700 miles per gallon of def. Your coworker is either lying or his wife fills it up for him.

Thanks for the info. I’m not that far off of yours.

 

[MEGA HO]

Def works on exhaust temps mainly the more nox gas the more def needed to break it down so when the auto and active regens make the system run hotter more def is used to keep the nox from exiting the scr

Thanks for the explanation, it makes sense now.

 

[RVTRKN]

I only got 460'ish miles on 10 gallons of DEF, for this 5k mile period. I did tow my new Pontoon boat for @ 1500 miles though. I had several Vegas to Havasu AZ trips, for dealer options installed. Damn Covid screwed up deliveries, as well as delayed production on the Mercury Out board accessories.