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Regen criteria

Big larry said:
Can anyone tell me what makes my 2020 3500 go into regen? I have been kind of trending when it goes in and how long it takes to get out of regen. My regen gauge never goes above half. It seems to regen after 150 miles or so and takes at least twenty miles to clear. If I stop and turn the truck off before regen finishes, does it start over or continue where it was?
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I thought I was in deep doo doo. I foolishly stopped the truck in the middle of a regen cycle (2023 ram 2500 Cummins 6.7HD). The next morning I got a message that said that I had to take it to the dealer dealer service was required for my DPF. The dealer told me that I may be locked out of any kind of a regen and that it would probably have to come to the dealer to be serviced. My owner manual also said that I would be locked out of Regen and would have to go to the dealer however.... I took it upon myself to try. I hooked up my 7000 pound travel trailer and pulled it at 40 to 45 mph on flat terrain. I forced the transmission into one gear lower so they're at stayed a little bit higher than normal. Regen cycle started right away and cleared the dpf in about 22 minutes. Moral of the story is don't always trust what the manual or the dealer says use your logic and smarts.
 
Lokomotive said:
I thought I was in deep doo doo. I foolishly stopped the truck in the middle of a regen cycle (2023 ram 2500 Cummins 6.7HD). The next morning I got a message that said that I had to take it to the dealer dealer service was required for my DPF. The dealer told me that I may be locked out of any kind of a regen and that it would probably have to come to the dealer to be serviced. My owner manual also said that I would be locked out of Regen and would have to go to the dealer however.... I took it upon myself to try. I hooked up my 7000 pound travel trailer and pulled it at 40 to 45 mph on flat terrain. I forced the transmission into one gear lower so they're at stayed a little bit higher than normal. Regen cycle started right away and cleared the dpf in about 22 minutes. Moral of the story is don't always trust what the manual or the dealer says use your logic and smarts.
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It's ok, thou not ideal, to shut down during a regen. The message was likely not related to the shut down.

You don't need to downshift to help a regen, that actually makes it harder for the regen to occur as the engine load is lower and exhaust flow is higher so it takes more fuel injected in the exhaust stroke.

Glad you got it cleared up and towing definitely helps an active regen.
 
AH64ID said:
You don't need to downshift to help a regen, that actually makes it harder for the regen to occur as the engine load is lower and exhaust flow is higher so it takes more fuel injected in the exhaust stroke.
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I'm a bit confused on this subject. Is there a Minimum RPMs to keep the regen on? If so, what are the minimum RPMs to keep the regen operational? Won't it turn off if it gets below the minimum RPMs?
 
John Jensen said:
I'm a bit confused on this subject. Is there a Minimum RPMs to keep the regen on? If so, what are the minimum RPMs to keep the regen operational? Won't it turn off if it gets below the minimum RPMs?
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I’ve never seen a minimum rpm for active regen and the lower the rpm’s the quicker the DPF is able to heat, at least from what I’ve seen on my CTS3.
 
AH64ID said:
I’ve never seen a minimum rpm for active regen and the lower the rpm’s the quicker the DPF is able to heat, at least from what I’ve seen on my CTS3.
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Does that mean a regen will continue/complete if stopped and idling?
 
John Jensen said:
Does that mean a regen will continue/complete if stopped and idling?
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In gear yes they will contiue for a while, but not indefinatly. I personally haven't noticed my truck stop regen with stop and go in gear, but others on the forum have.

In Park the regen stops almost instantly.

56ram2500 said:
I've noticed I get faster passive regens at speeds between 25-50 mph on slower curved, slightly hilled county roads compared to steady hwy speeds of 55-68 mph
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Same, up to about 45 or so is where I see it. The rpms are low enough that the EGT's are high despite the lower fuel burn.
 
AH64ID said:
It's ok, thou not ideal, to shut down during a regen. The message was likely not related to the shut down.

You don't need to downshift to help a regen, that actually makes it harder for the regen to occur as the engine load is lower and exhaust flow is higher so it takes more fuel injected in the exhaust stroke.

Glad you got it cleared up and towing definitely helps an active regen.
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Right- not ideal to shutdown in the middle of a regen, but risky in that you continue to load up the DPF and if you're already too loaded, it could trigger the 'mandatory dealer service' message. Who knows however what their software does and what trigger criteria they use. I would have to respectively disagree about the down shift not helping .... downshifting does NOT decrease the load- I'm still pulling the same load at the same speed, but burning more fuel which will increase exhaust temp. From a thermodynamics view that makes perfect sense- Same amount of load requires the same amount of fuel burn to move it so the additional fuel spent by the faster spinning engine has to turn into heat and go out the exhaust - not into the constant load.
 
Lokomotive said:
Right- not ideal to shutdown in the middle of a regen, but risky in that you continue to load up the DPF and if you're already too loaded, it could trigger the 'mandatory dealer service' message. Who knows however what their software does and what trigger criteria they use.
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I definitely try to avoid shutting down during a soot based regen because I think that can actually cause the regen to end early, which isn't good. Shutting down during a 24 hour based regen isn't as much of a concern.

Lokomotive said:
I would have to respectively disagree about the down shift not helping .... downshifting does NOT decrease the load- I'm still pulling the same load at the same speed, but burning more fuel which will increase exhaust temp. From a thermodynamics view that makes perfect sense- Same amount of load requires the same amount of fuel burn to move it so the additional fuel spent by the faster spinning engine has to turn into heat and go out the exhaust - not into the constant load.
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The added gearing reduction from the downshift means you need to produce less torque at the engine to maintain the same torque at the wheels. The added fuel from higher rpms in insignificant in terms of EGTs and more than counteracted by the increase in airflow. The increased airflow thru the engine makes the combustion temps lower.

If you really want to witness it then get yourself something that monitors EGT's as well as engine load and see for yourself. Same speed, same load and a lower gear means lower EGT's and a lower engine load. It's a common misnomer than downshifting will help active regen but the data says otherwise.

That being said, a good spirited high rpm and high boost acceleration during or right after an active regen can help blow things out and I've seen very positive results from that on the DPF delta psi readings.
 
Lokomotive said:
I would have to respectively disagree about the down shift not helping .... downshifting does NOT decrease the load- I'm still pulling the same load at the same speed, but burning more fuel which will increase exhaust temp. From a thermodynamics view that makes perfect sense- Same amount of load requires the same amount of fuel burn to move it so the additional fuel spent by the faster spinning engine has to turn into heat and go out the exhaust - not into the constant load.
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Yeah, you'd think thats the way it works. But it isn't. I know this because I had the Banks iDash on my 06 which would monitor EGT. When pulling a load, the more the truck "lugged down" in a higher gear and lower RPM's, the EGT would increase significantly. Downshifting or flipping the OD OFF switch and bringing the RPMs up would lower the EGT. This was the case no matter the terrain, flat straights or steep hills.
 
ErikTheRed said:
Yeah, you'd think thats the way it works. But it isn't. I know this because I had the Banks iDash on my 06 which would monitor EGT. When pulling a load, the more the truck "lugged down" in a higher gear and lower RPM's, the EGT would increase significantly. Downshifting or flipping the OD OFF switch and bringing the RPMs up would lower the EGT. This was the case no matter the terrain, flat straights or steep hills.
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Absolutely. I monitor this daily on my iDash. Dropping a gear almost always results in lower EGT’s. I do limit 6th on back roads and slower speed roads, but that’s to avoid the gear searches in some situations and to keep the truck from getting too low in rpm. On the highway, dropping to fifth or fourth and massively increasing rpm is always a drop in EGT temp.
 
John Jensen said:
When my Ecodiesel is in active regen, driving in town with frequent long stops at major intersection stop lights I put it in Park, keeping the RPMs at 2000-2500, it has never stopped.
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Not sure what ram uses for their ecodiesel program logic, but the 6.7 trucks are basically a carbon copy of Cummins’ own regen programming. Since the ecodiesel is a euro based engine, I’d assume the programming is either in-house or borrowed from overseas.
 
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