So who else has the WORST regen timing?

[ErikTheRed]

Just got back from a 400-mile round trip to Bass Lake, not towing anything. Even at highway speeds of 65 to 75 mph most of the way, the empty truck struggled to make EGT3 temps above 650. Probably 80% of the drive my EGT3 temps were high 500's to low 600's. We know that when EGT3 temps are at 650, at least some passive regen is occurring. But here's my question-- with soot accumulating in the DPF when under 650 degrees, does LESS soot accumulate at higher temps? Like, if actual soot accumulation levels could be measured in real time, would soot accumulation be greater at 450 degrees compared to 600 degrees? More simply, does lower DPF temps always mean greater/faster soot accumulation? Common sense tells me yes. If so, then driving those long highway stretches, sometimes for hours at a time, and the EGT3 temps are at 600ish, it would be somewhat comforting to know that while passive regen may not be happening, at least soot is accumulating more slowly than it would be if I were just zipping around our stoplight-infested town.

 

[jetlag]

Absolutely, how many engine hours?

The truck will regen based on soot loading or engine hours, not miles.

Thank You, did not know that. I will come back with the engine hours shortly. While I am asking, how long does the regens last?

 

[ErikTheRed]

While I am asking, how long does the regens last?

My 6500-mile 2024 has never performed a soot-based regen, only time-based 24-hr regens. But in my experience, regens typically take about 10 to 12 miles of driving at highway speeds of 55mph or greater when the DPF3 temp will exceed 900 degrees. I think the amount of time an active regen should last depends on things like soot-based or time-based regen, actual soot load in the DPF when the regen starts, sustained DPF temps achieved during the regen, driving conditions, etc. There is no one-size-fits-all answer for "how long does a regen cycle take", too many variables.

 

[jetlag]

My 6500-mile 2024 has never performed a soot-based regen, only time-based 24-hr regens. But in my experience, regens typically take about 10 to 12 miles of driving at highway speeds of 55mph or greater when the DPF3 temp will exceed 900 degrees. I think the amount of time an active regen should last depends on things like soot-based or time-based regen, actual soot load in the DPF when the regen starts, sustained DPF temps achieved during the regen, driving conditions, etc. There is no one-size-fits-all answer for "how long does a regen cycle take", too many variables.

Thanks, will I see a particular number/percentage on the gauge? I know when it ends just based on the fuel mileage increase. All the driving I have done so far has been short, a few highway miles. Today we take it to Myrtle Beach, about 165 miles, so it should resolve itself.

 

[ErikTheRed]

Thanks, will I see a particular number/percentage on the gauge?

The only thing you'll see on the truck's gauge is "Regeneration In Progress" while a regen is occurring, but only if/when you have the EVIC on the DPF display. A Banks IDash gauge (and others) will show you more details, such as when to expect a regen to occur based on soot load or time, when its actually happening, and what your approximate soot load is as soon as its finished. The IDash will also display the DPF outlet temp so you can see when passive regen is occurring and also the DPF temps while an active regen is underway.

 

[OLEJOE]

can a new truck go into a regen cycle with under 700 miles? I noticed this morning the instant fuel mileage at 55 MPH went from around 19-20 to 15 and almost stuck there. At home, in the garage, I noticed a burning smell. How can I tell for sure that is what it is doing?

I got my first regen at 300 miles pulling out of the dealership driveway after having recall work done. Im pretty sure they idled the truck the entire 2 hours I was there. Had 14 hours total at 300 miles and I never idle it.

 

[ErikTheRed]

Just got back from a 400-mile round trip to Bass Lake, not towing anything. Even at highway speeds of 65 to 75 mph most of the way, the empty truck struggled to make EGT3 temps above 650. Probably 80% of the drive my EGT3 temps were high 500's to low 600's. We know that when EGT3 temps are at 650, at least some passive regen is occurring. But here's my question-- with soot accumulating in the DPF when under 650 degrees, does LESS soot accumulate at higher temps? Like, if actual soot accumulation levels could be measured in real time, would soot accumulation be greater at 450 degrees compared to 600 degrees? More simply, does lower DPF temps always mean greater/faster soot accumulation? Common sense tells me yes. If so, then driving those long highway stretches, sometimes for hours at a time, and the EGT3 temps are at 600ish, it would be somewhat comforting to know that while passive regen may not be happening, at least soot is accumulating more slowly than it would be if I were just zipping around our stoplight-infested town.

Anyone??

 

[Trash Panda]

Anyone??

The actual accumulation of soot is a more complicated process than that, but yeah, in general the higher EGT is indicative of less soot loading.

65-75mph unloaded has been kind of the gray zone for my 22. Not enough to passive regen, but not really accumulating much either.

 

[jetlag]

Our trip to Myrtle Beach was uneventful. The regen cycle persisted for about 15-20 miles before the milage jumped. I watched the gauge from time to time and it remained between 10-20% most of the way. We are now on our first trip pulling the camper, 16500 pounds, presently at Natural Bridge, VA. about 375 miles and no regens I could detect. The last few days we have been piddling about, including a drive on the Parkway, with very slow speeds, so we could enjoy the hills. Yesterday, the gauge was reading 30%, and today we drive to Charlottesville and back, about 50 miles, without the trailer.

 

[AH64ID]

The actual accumulation of soot is a more complicated process than that, but yeah, in general the higher EGT is indicative of less soot loading.

65-75mph unloaded has been kind of the gray zone for my 22. Not enough to passive regen, but not really accumulating much either.

Same for my ‘22. I used this rule of thumb…

At 22+ mpg there isn't any passive regen, 18-22 mpg is more of a net neutral, and anything less than 18 mpg will have continuous passive regen. Below 12 mpg and you're cleaning it failry quickly.

 

[ErikTheRed]

Same for my ‘22. I used this rule of thumb…

At 22+ mpg there isn't any passive regen, 18-22 mpg is more of a net neutral, and anything less than 18 mpg will have continuous passive regen. Below 12 mpg and you're cleaning it failry quickly.

I guess I've never heard it in terms of MPG's, but it makes sense. The more fuel being burned means more heat in the DPF. I use temps, or more specifically, EGT 3 temps, to determine passive regen.... and if I'm not mistaken, it was your advice that led me to do so.

 

[jetlag]

Back from our round trip to Charlottesville, VA yesterday. The Gauge was showing 30% when we started and 10% at the end. The fuel average went from 16.7 to 18.1 on the way there, and 17.1 at the end. Mind you, we were driving on I-64 in the mountains. I drove at the speed limit, 70MPH

 

[AH64ID]

I guess I've never heard it in terms of MPG's, but it makes sense. The more fuel being burned means more heat in the DPF. I use temps, or more specifically, EGT 3 temps, to determine passive regen.... and if I'm not mistaken, it was your advice that led me to do so.

EGT 3 temps are what allows passive regen to occur, MPG’s are simply another correlation tool.

Both EGTs and MPGs have been mentioned in multiple threads, MPGs more so for folks that don’t have OBDII monitors but also as another tool for everyone.

Above 22 mpg average there will be insufficient temps in the DPF to possibly regen, even if they bounce in and out of range on EGT3. Soot accumulation is slow due to the efficiency of the motor.

18-22 mpg’s there is some heat in the exhaust but not enough to really cook the soot out of the DPF, but soot production is so low that there really isn’t any accumulation in the DPF.

Etc… it’s a generalization that was fairly accurate on my ‘22.

The issues aside, the Ram DPF and regen strategy is far easier to predict/understand than the one MB uses in my Sprinter.

 

[ErikTheRed]

To use MPG as a measure of passive regen, we must be referring to highway-only MPG..... because none of us are getting 18+ MPG running around town stoplight to stoplight, more like 4 to 8. If thats the case, then around-town driving should be the best way to keep the DPF squeaky-clean!

 

[AH64ID]

To use MPG as a measure of passive regen, we must be referring to highway-only MPG..... because none of us are getting 18+ MPG running around town stoplight to stoplight, more like 4 to 8. If thats the case, then around-town driving should be the best way to keep the DPF squeaky-clean!

It’s not based on highway, but certainly more steady state. Where I live that’s not just on highway/interstate. It’s based on average not instantaneous, even short term average is enough to impact the DPF. Think about baking something in your oven, it’s not done as soon as you put it in the hot air it takes time.

That rule of thumb worked for me highway and around town, but I never did what I would call city driving enough to see how regen was impacted. Once I spent a 8 days in the SLC with short commutes and it took nearly 100 miles of interstate at 70+ to bring the dash DPF gauge to 0, and it didn’t really happen until 80+. That’s when I started correlating mpg to EGT3 and the average mpg’s to sustain better passive regen at higher speeds empty.

I can also assure you that 4-8 was not ever my average stoplight to stoplight. My one city driving tank mentioned above was 14.6 (had one day of 8 with a highway drive, insufficient to bring the average up too much) Heck I only got that low towing or hunting, and hunting was sufficient passive regen to make 24 hours despite the low speed (one 24 hour regen was only 197 miles).

Honesty it’s no different than EGT3 stoplight to stoplight. You might see 700-750° accelerating but your average isn’t there for sufficient passive regen, and that’s what matters.

 

[ErikTheRed]

Honesty it’s no different than EGT3 stoplight to stoplight. You might see 700-750° accelerating but your average isn’t there for sufficient passive regen, and that’s what matters.

Exactly. It takes SUSTAINED 650°+ temps for passive regen. (I learned that from some guy on the interwebs ).

I just got my first little blip on the DPF gauge yesterday that didn't clear after a key cycle. My most recent regen (24 hr) was about 560 miles ago, and when the regen completed, the IDash showed DPF @ 1%. Its now showing 60% but that's because the count has switched from soot to time. About 450 of that 560 miles was highway driving but I was only seeing 575 to 625° so kinda in that "neutral zone", which means that blip showed up from just over 100 miles of around town. That doesn't seem good. I'm curious to see how long it'll take to get another blip on the gauge. I'm gonna keep driving it around town and see what happens.