2025 Cummins Regen Observations

[Brutal_HO]

I wasn't expecting it, but there's definitely a low end grumble when in regen. Sounds like light exhaust braking, but only when in gear and most noticable at idle or low speed

I believe it's been noted by others the EB is activating to assist with regen. Be interesting to know if that's passive only or passive/active.

 

[m.stephen.miller]

I believe it's been noted by others the EB is activating to assist with regen. Be interesting to know if that's passive only or passive/active.

That makes sense. It was definitely the case during the first regen on mine at 24 hours.

 

[AH64ID]

With the 7th injector, I wouldn't expect the engine to be working harder (raising EGT) to avoid or assist regen.

Even with the 7th injector it’s beneficial to raise EGT’s to assist with regen. By retarding timing and restricting the exhaust the EGTs will rise and improve the DOC’s function.

I wasn't expecting it, but there's definitely a low end grumble when in regen. Sounds like light exhaust braking, but only when in gear and most noticable at idle or low speed

I definitely noticed that on my 18 and 22, as well as dad’s 17 and 22. The tuning changes to increase EGTs.

 

[PyroJoe]

My first 1500 miles were almost all interstate. My DPF gauge rose to ~30% rather quickly, then seemed to stay there. Around maybe 14 engine hours, I noticed the DPF gauge had dropped back to zero. I'm at 27 engine hours now and the DPF gauge is back up to ~30%. I have the 7" display, so I'll keep an eye on the DPF gauge to see if it alerts that it's doing a regen. Sucks it doesn't just show up as an idiot light like my skidsteers do. I could have sworn this '25 did show an idiot light, but it's been a long couple days making that trip on minimal sleep. I think maybe I happened to be on the DPF gauge when it was doing a regen, and the white DPF symbol turned yellow.
Also, I kept an eye on things at the 24 engine-hour mark, and did not notice a regen or drop in the DPF gauge.

Did they delete the muffler for 2025 or have these not had one for a while now? It's almost annoying how quiet this truck is. My other daily drivers are a 12 valve and a 24 valve. This thing isn't even in the same league.

 

[flan]

My first 1500 miles were almost all interstate. My DPF gauge rose to ~30% rather quickly, then seemed to stay there. Around maybe 14 engine hours, I noticed the DPF gauge had dropped back to zero. I'm at 27 engine hours now and the DPF gauge is back up to ~30%. I have the 7" display, so I'll keep an eye on the DPF gauge to see if it alerts that it's doing a regen. Sucks it doesn't just show up as an idiot light like my skidsteers do. I could have sworn this '25 did show an idiot light, but it's been a long couple days making that trip on minimal sleep. I think maybe I happened to be on the DPF gauge when it was doing a regen, and the white DPF symbol turned yellow.
Also, I kept an eye on things at the 24 engine-hour mark, and did not notice a regen or drop in the DPF gauge.

Did they delete the muffler for 2025 or have these not had one for a while now? It's almost annoying how quiet this truck is. My other daily drivers are a 12 valve and a 24 valve. This thing isn't even in the same league.

They have not had a muffler since 2007.5, the introduction of the 6.7. The doc, dpf and scr cut the noise down to a whisper.

 

[m.stephen.miller]

As a quick update, I am averaging about 600 miles and 17 engine hours between regens. The regens definitely seem to take awhile without a load - my last regen was 84 minutes while driving 75 mph unloaded the entire time. There was about a 5-6 mpg loss during the regen on the EVIC (jumps right from about 13 mpg to 19 mpg once regen completes). By my math, that means about 2.5 additional gallons of fuel used for the regen. I had one time-based active regen while towing, and that was much faster (maybe 10-20 mins).

 

[PyroJoe]

Is there a way to see regen status with the OBDLink MX+ ?

 

[m.stephen.miller]

Is there a way to see regen status with the OBDLink MX+ ?

Not that I am aware of, but I have found it obvious when in regen; around town, the idle is a much lower grumble (sounds like the exhaust brake), and on the highway the instantaneous MPG is down 5-6 mpg during regen, and immediately bumps back up when the regen completes. My last regen started with DPF gauge at 40% - heard the grumble @ idle, saw the decrease in hwy MPG, and over 84 mins the DPF gauge went from 40% to 0% after which the MPG went right back up to normal. There is also a change in smell, but only from outside the truck.

 

[scdo]

Is there a way to see regen status with the OBDLink MX+ ?

Yes, you can configure a PID for DPF Regen Status. It returns 0 or 1 to show when regen is active. I can confirm it works on the 25s.

 

[PyroJoe]

Yes, you can configure a PID for DPF Regen Status. It returns 0 or 1 to show when regen is active. I can confirm it works on the 25s.

Ok, that's what I had pulled up. Was expecting it to read "on" or something. I'll keep an eye out for a "1".

 

[scdo]

Ok, that's what I had pulled up. Was expecting it to read "on" or something. I'll keep an eye out for a "1".

I set mine as a meter 0-1 I think so it sorta changes color when it moves to 1 as well.

 

[HarryN]

As a quick update, I am averaging about 600 miles and 17 engine hours between regens. The regens definitely seem to take awhile without a load - my last regen was 84 minutes while driving 75 mph unloaded the entire time. There was about a 5-6 mpg loss during the regen on the EVIC (jumps right from about 13 mpg to 19 mpg once regen completes). By my math, that means about 2.5 additional gallons of fuel used for the regen. I had one time-based active regen while towing, and that was much faster (maybe 10-20 mins).

Thanks for that info. So locally diesel is ~ $5 / gallon, plus a gallon of DEF would be ~ $15 per regen. Adds up.

 

[AH64ID]

Thanks for that info. So locally diesel is ~ $5 / gallon, plus a gallon of DEF would be ~ $15 per regen. Adds up.

Why would you factor DEF into regen cost?

 

[AndyRoos]

With the 7th injector, I wouldn't expect the engine to be working harder (raising EGT) to avoid or assist regen.

I wonder if there is any proof of this additional injector. My observation is that during regeneration engine sounds differently. While idling - the difference is audible - once in regen - you can hear it stops when you put the car in "Park". Going back to "Drive" or even "Neutral" puts the engine back in regen mode with a bit harder operation.
Edit:
Meanwhile I was able to find in different thread that it's true - there is 7-th injector just before DOC which is integrated with DPF in one body.

 

[AH64ID]

I wonder if there is any proof of this additional injector. My observation is that during regeneration engine sounds differently. While idling - the difference is audible - once in regen - you can hear it stops when you put the car in "Park". Going back to "Drive" or even "Neutral" puts the engine back in regen mode with a bit harder operation.
Edit:
Meanwhile I was able to find in different thread that it's true - there is 7-th injector just before DOC which is integrated with DPF in one body.View attachment 86333

Even with the 7th injector there are engine parameters that change to raise the EGTs without injecting raw fuel, such as opening of the VGT and retarding timing. Those differences will make the engine sound different.

 

[PyroJoe]

Got my CTS3 plugged in. You can view regen status, time between regens, miles between regens, a percent meter, and a few other things like pressure deltas.
There are also 6 EGT probes listed.
Haven't been able to find Transmission Gear/Lock-up status, so I'm not sure I'll be keeping this in this truck or not.

 

[AH64ID]

Got my CTS3 plugged in. You can view regen status, time between regens, miles between regens, a percent meter, and a few other things like pressure deltas.
There are also 6 EGT probes listed.
Haven't been able to find Transmission Gear/Lock-up status, so I'm not sure I'll be keeping this in this truck or not.
View attachment 86368

I'm curious if time and distance between regens is reported accurately on the 25's, it wasn't on my 22.

I had planned to keep my CTS3 and put it in my Hemi but when I did there wasn't gear/lockup status so now I'm leaning towards selling it.

 

[ZF.Transmission.Guy]

Got my CTS3 plugged in. You can view regen status, time between regens, miles between regens, a percent meter, and a few other things like pressure deltas.
There are also 6 EGT probes listed.
Haven't been able to find Transmission Gear/Lock-up status, so I'm not sure I'll be keeping this in this truck or not.
View attachment 86368

Generally, your torque converter will lock up once above ~14mph(give or take a few mph), and unlock when decelerating at around 13mph(when exhaust brake would exit). Torque converter stays open when trans fluid temp is below 0*Celsius

 

[ZF.Transmission.Guy]

I'm curious if time and distance between regens is reported accurately on the 25's, it wasn't on my 22.

I had planned to keep my CTS3 and put it in my Hemi but when I did there wasn't gear/lockup status so now I'm leaning towards selling it.

IT might depend on your cluster option, but there should be an option to display the current gear in the settings. If not, you can just hit the - button on the steering wheel gear selection buttons, set max gear to 8th, and it will show your current gear as well

 

[PyroJoe]

Lock up is what I want to see displayed. They were advertising lock up capability in 1st gear, but I haven't been able to achieve it yet.