exactly, this is the question my original post on this thread asked: If my exhaust gases are hot enough, do I bypass regen?
The consensus here is yes.
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engine didn’t regen at all 6k miles
- Thread starter jeffn
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The consensus here is yes.
flan
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I’ve been running up I-95 with a 8k camper in tow (full send) and had a regen trigger. As a matter of fact several times while towing with a less than aero dynamic load had one go in. Even with 0% showing on the gage.
GPurcell01
Well-Known Member
From the Cummins ISB service manual - may vary a little with our trucks but here it is anyways.
Passive regeneration occurs when the exhaust temperatures are naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than the soot is collected.
Passive regeneration typically occurs when the temperature of the aftertreatment DPF is above 316°C [600°F]. This occurs during highway driving or when driving with heavy loads.
Since passive regeneration occurs naturally, it is considered to be normal engine operation. No fuel is added to the exhaust stream during passive regeneration. Active regeneration occurs when the exhaust temperatures are not naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than it is collected.
Active regeneration requires assistance from the engine in order to increase the exhaust temperature. This is typically done by injecting a small amount of diesel fuel into the exhaust stream (called aftertreatment injection) which is then oxidized by the aftertreatment DOC. The oxidation of this additional fuel creates the heat needed to regenerate the aftertreatment DPF.
For active regeneration to occur, the ECM must detect that the aftertreatment DPF restriction has reached a specified limit. Once this limit is reached, the engine will alter its operation in order to create exhaust temperatures high enough to actively regenerate the aftertreatment DPF. Aftertreatment injection requires that temperatures in the aftertreatment system reach approximately 288°C [550°F]. At this temperature and above, the small quantities of fuel injected into the exhaust will properly oxidize across the aftertreatment DOC, creating the additional heat required to actively regenerate the aftertreatment DPF.
Passive regeneration occurs when the exhaust temperatures are naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than the soot is collected.
Passive regeneration typically occurs when the temperature of the aftertreatment DPF is above 316°C [600°F]. This occurs during highway driving or when driving with heavy loads.
Since passive regeneration occurs naturally, it is considered to be normal engine operation. No fuel is added to the exhaust stream during passive regeneration. Active regeneration occurs when the exhaust temperatures are not naturally high enough to oxidize the soot collected in the aftertreatment DPF faster than it is collected.
Active regeneration requires assistance from the engine in order to increase the exhaust temperature. This is typically done by injecting a small amount of diesel fuel into the exhaust stream (called aftertreatment injection) which is then oxidized by the aftertreatment DOC. The oxidation of this additional fuel creates the heat needed to regenerate the aftertreatment DPF.
For active regeneration to occur, the ECM must detect that the aftertreatment DPF restriction has reached a specified limit. Once this limit is reached, the engine will alter its operation in order to create exhaust temperatures high enough to actively regenerate the aftertreatment DPF. Aftertreatment injection requires that temperatures in the aftertreatment system reach approximately 288°C [550°F]. At this temperature and above, the small quantities of fuel injected into the exhaust will properly oxidize across the aftertreatment DOC, creating the additional heat required to actively regenerate the aftertreatment DPF.
DougB
Well-Known Member
My 2022 SO only has 1000mi on it and I’ve seen it regen only once and it worked exactly as described by @jeffn above. The iDash showed regen ON, the EVIC showed Regen in Progress after it was about half way on the graph. Today on a quick trip I noticed the iDash DPF% at nearly 98 but I didn’t check the EVIC. Expect it’ll go regen soon.
Good to learn about Passive Regen.
I wish… I used 600+ gallons of diesel on this trip and about 30 gallons of DEF. It might be more or less, I top up the DEF from the pump when I get fuel and don’t pay a lot of attention to how much I am pumping.
I have had my 2021 since Sept now with 1500 miles and had about 3 regens occur that I've noticed. My DEF guage is just a little under 3/4 and I have never added yet. From my observations which are not guaranteed because I don't pay that much attention to it , my gauge will stay at zero for a while but over time creep up to 50 % then it will regen. I'm retired so I mainly use it for short milk runs and errands and rarely see the highway. I will not be towing till the spring so I have no idea what she will do then.
Nick
Well-Known Member
When I tow it never shows a build up on the DPF gauge . Only when driving around in stop and go ,basically when empty. When mine was new it threw a code . Took it in and the dealer said it wasn't regening. You will see a check engine light if there is a problem .
Tazmanianfj
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I found that the app OBDLink can see the average distance and time for active regens. When connected it will show the values.
Made an appointment at the dealer, which surprisingly turned out to be a good experience. The truck did have a series of error codes about 5k miles earlier, which would have been somewhere around New Mexico and Texas on leg 1 of my previous trip. The one that caught my attention was P0234 Turbo Overboost.
Potential causes for this error include: Exhaust restriction, low EGR flow, malfunctioning intake throttle body, maf sensor, turbocharger, Map sensor, PCM.
He called me a day later and said the truck appears and functions normal. They cleared the codes and inspected the throttle body, waste gate, exhaust system, and turbo. No error codes generated, no corrosion, no oil leaks, no air leaks. The computer also told them the truck had “regen’ed 14 hours ago” which would have been in their shop. I don’t know what to think but I agree the truck is operating normally. They reflashed the computer and there was a software update, so now that I have it back the normal behavior could be different than what I previously observed.
Couple of other things I learned:
- the Y26 lug nut recall requires special equipment for testing the length of the wheel studs and they do not have that equipment. I have zero concern about this recall, am just tired of getting nag notices from RAM.
- the Y78 fuel pump recall is far more important to me. The dealer has no information on the replacement part kit, process steps, or when they will get it. Other than the recall alert they have received no updated information.
Potential causes for this error include: Exhaust restriction, low EGR flow, malfunctioning intake throttle body, maf sensor, turbocharger, Map sensor, PCM.
He called me a day later and said the truck appears and functions normal. They cleared the codes and inspected the throttle body, waste gate, exhaust system, and turbo. No error codes generated, no corrosion, no oil leaks, no air leaks. The computer also told them the truck had “regen’ed 14 hours ago” which would have been in their shop. I don’t know what to think but I agree the truck is operating normally. They reflashed the computer and there was a software update, so now that I have it back the normal behavior could be different than what I previously observed.
Couple of other things I learned:
- the Y26 lug nut recall requires special equipment for testing the length of the wheel studs and they do not have that equipment. I have zero concern about this recall, am just tired of getting nag notices from RAM.
- the Y78 fuel pump recall is far more important to me. The dealer has no information on the replacement part kit, process steps, or when they will get it. Other than the recall alert they have received no updated information.
fuchsroehre
Active Member
I heard or read somewhere that Semis have a force regeneration button on the dash.
Wondering why our trucks would not have such? I imagine that forcing DPF regens does not hurt but the opposite does. People might shut off the truck not even knowing that a regen just started. Who knows if the regen starts up when you start the truck next day?
I wish the truck makes it more obvious that an active regen is going on, its very rare that the DPF gauge is showing on my dash.
BTW my truck never showed the DPF gauge at anything above 0% but it states active regen even towing a camper trailer on long trips. Its probably tougher to generate high enough exhaust temps at low ambient temps 0F vs 100F. So maybe more active regens in the winter vs summer.
Wondering why our trucks would not have such? I imagine that forcing DPF regens does not hurt but the opposite does. People might shut off the truck not even knowing that a regen just started. Who knows if the regen starts up when you start the truck next day?
I wish the truck makes it more obvious that an active regen is going on, its very rare that the DPF gauge is showing on my dash.
BTW my truck never showed the DPF gauge at anything above 0% but it states active regen even towing a camper trailer on long trips. Its probably tougher to generate high enough exhaust temps at low ambient temps 0F vs 100F. So maybe more active regens in the winter vs summer.
I am sure that means 14 engine hours ago not literally 14 hours ago. So if it is like mine it will regen in again in 10 hours of engine run time.
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CharlieL
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I know my truck has regen'd at least three times before over its current 3,947 miles. Each time I had been watching the DPF screen creep up, had that screen displayed & the screen switched to the regen message, satisfying my curiosity. For the first time, today I was driving along (in town) with the speedo displayed & knowing the DPF was just shy of 50%, when the regen message popped up. First time I've had this happen & seen this message. Didn't finish by the time I parked in my garage, so I guess I'm currently in violation of the truck's directive to "Continue Driving!" 
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flan
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I think that’s when a certain parameter is set letting you know things are a little more sooted up than usual. It’s a good idea to run that out if possible. If you cancel it too many times a trip to the dealer for a forced regen will be in your future.I know my truck has regen'd at least three times before over its current 3,947 miles. Each time I had been watching the DPF screen creep up, had that screen displayed & the screen switched to the regen message, satisfying my curiosity. For the first time, today I was driving along (in town) with the speedo displayed & knowing the DPF was just shy of 50%, when the regen message popped up. First time I've had this happen & seen this message. Didn't finish by the time I parked in my garage, so I guess I'm currently in violation of the truck's directive to "Continue Driving!"
CharlieL
Well-Known Member
Point taken. In my post I attempted a bit of humor concerning the AI of my truck! Since the last regen my truck has only seen city driving; not a surprise it needs to clean out the soot. This isn't going to happen very quickly with my city-driving habits. My commute is short - I have a home office. Running usual errands doesn't get me up over 40 mph very often. I intend to take my truck for a highway run this weekend to make the full regen happen.
All levity aside, I take the health and maintenance of my machines very seriously. I don't have EGT info for my RAM; unlike the very precise digital 4-cylinder CHT/EGT gauge for the Lycoming engine in my flying machine. This provides superb information about the condition of each cylinder as well as operation (i.e. leaning at altitude for peak efficiency). Having this in the RAM would be a great way to monitor what's up, as well as be able to answer some questions posted by others about the temps reached during the regen.
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Darmichar
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Even in passive regeneration, DEF will be used. It is injected to help the SCR remove NOx from the exhaust stream prior to the soot being trapped/burned in the DPF.
H3LZSN1P3R
You're doing it wrong
It constantly uses def anytime the scr exhaust temps are high enough so anytime you are taking off from a stop or cruising up a hill
All levity aside, I take the health and maintenance of my machines very seriously. I don't have EGT info for my RAM; unlike the very precise digital 4-cylinder CHT/EGT gauge for the Lycoming engine in my flying machine. This provides superb information about the condition of each cylinder as well as operation (i.e. leaning at altitude for peak efficiency). Having this in the RAM would be a great way to monitor what's up, as well as be able to answer some questions posted by others about the temps reached during the regen.[/QUOTE]
Yep - I imaging that engine malfunctions at altitude are hazardous to your health lol
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Yep - I imaging that engine malfunctions at altitude are hazardous to your health lol
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Yep - I imaging that engine malfunctions at altitude are hazardous to your health lol
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[/QUOTE]
Curious, how can you enjoy your truck when you are so concerned about the perimeters of the engine? I tow often and have never had any concern that my truck couldn't handle it.