2025 Cummins Regen Observations

<div class="bbWrapper">It&#039;s very strange to me. Bank 1 Sensor 1 is much cooler than the rest. Bank 1 Sensor 2 gets the hottest, having gotten as high as 997° today. I&#039;m still only at 88% on the DPF trigger. I have a 200 mile trip coming up, so hopefully it&#039;ll go into a full regen and all of this will go away. It&#039;s absolutely killing my mileage right now while it&#039;s doing whatever it&#039;s doing.<br /> <br /> Update: I typed this post right after parking at the shop. Had to hop back on the road maybe 30min later, and it&#039;s no longer doing it. Also note that this whole time it appeared to be doing some kind of regen, the DPF meter kept climbing instead of decreasing. I&#039;m at 90% as of now. MPG is back to normal as well as temps.<br /> <br /> <a href="https://hdrams.com/forum/attachments/20250813_132740-jpg.88641/" target="_blank"><img src="https://hdrams.com/forum/data/attachments/88/88649-b62bbb207cd9540c3909d75973e9fabb.jpg?hash=th1qytuMvI" class="bbImage " style="" alt="20250813_132740.jpg" title="20250813_132740.jpg" width="267" height="150" loading="lazy" /></a></div>
 
Last edited:
<div class="bbWrapper"><blockquote data-attributes="member: 50240" data-quote="PyroJoe" data-source="post: 354361" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=354361" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-354361">PyroJoe said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> It&#039;s very strange to me. Bank 1 Sensor 1 is much cooler than the rest. Bank 1 Sensor 2 gets the hottest, having gotten as high as 997° today. I&#039;m still only at 88% on the DPF trigger. I have a 200 mile trip coming up, so hopefully it&#039;ll go into a full regen and all of this will go away. It&#039;s absolutely killing my mileage right now while it&#039;s doing whatever it&#039;s doing.<br /> <br /> Update: I typed this post right after parking at the shop. Had to hop back on the road maybe 30min later, and it&#039;s no longer doing it. Also note that this whole time it appeared to be doing some kind of regen, the DPF meter kept climbing instead of decreasing. I&#039;m at 90% as of now. MPG is back to normal as well as temps.<br /> <br /> <a href="https://hdrams.com/forum/attachments/88641/" target="_blank">View attachment 88641</a> </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>It is in line with what I see. There are two DOCs. One before SCR and second one before DPF.</div>
 
<div class="bbWrapper">Finally got to the next regen. It didn&#039;t start till about 2 miles after hitting 100% on the trigger. Bank 1 Sensor 6 is the gauge to watch for your max regen temp. I got right up to 1100° at one point. Another interesting observation was the trigger went from 100% to 64% instantly when it started.<br /> <br /> Question - Is it safe/worthwhile to park the truck in Neutral and let it finish the regen? Mine only quits regen in Park. Not sure if you can do elevated idle in Neutral, but I doubt it. I&#039;ve been planning to do a max mpg test tomorrow for the past 2 weeks. It&#039;s just my luck I&#039;m in the middle of a regen cycle now. Gonna have to just &quot;drive around&quot; tomorrow till it finishes.<br /> <br /> <a href="https://hdrams.com/forum/attachments/20250815_181452-jpg.88745/" target="_blank"><img src="https://hdrams.com/forum/data/attachments/88/88753-edc4eab8ba3133238bae5ffe559305ac.jpg?hash=crL7dqZWUD" class="bbImage " style="" alt="20250815_181452.jpg" title="20250815_181452.jpg" width="267" height="150" loading="lazy" /></a><a href="https://hdrams.com/forum/attachments/20250815_181811-jpg.88746/" target="_blank"><img src="https://hdrams.com/forum/data/attachments/88/88754-d2b7bc05f231d3de31faf0fd21624fb8.jpg?hash=WNnUoXZx4R" class="bbImage " style="" alt="20250815_181811.jpg" title="20250815_181811.jpg" width="267" height="150" loading="lazy" /></a><a href="https://hdrams.com/forum/attachments/20250815_183238-jpg.88747/" target="_blank"><img src="https://hdrams.com/forum/data/attachments/88/88755-d732bd316ee7af4c0e4d17fd4ca02e2a.jpg?hash=kXZQv0T9aB" class="bbImage " style="" alt="20250815_183238.jpg" title="20250815_183238.jpg" width="267" height="150" loading="lazy" /></a></div>
 
<div class="bbWrapper">I don&#039;t think you were in regen before, nothing indicated it. Something else was causing high EGT&#039;s, try looking at engine load. <br /> <br /> Regen will shutoff if you are stopped too long or put the truck in P (I think N too).</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 16713" data-quote="AH64ID" data-source="post: 355186" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355186" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355186">AH64ID said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> I don&#039;t think you were in regen before, nothing indicated it. Something else was causing high EGT&#039;s, try looking at engine load.<br /> <br /> Regen will shutoff if you are stopped too long or put the truck in P (I think N too). </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>How in the world would I have high engine load when parked and also while coasting down the highway? It was doing something weird with the DPF for sure. You don&#039;t just hit 1100° idling or coasting otherwise.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 50240" data-quote="PyroJoe" data-source="post: 355187" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355187" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355187">PyroJoe said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> How in the world would I have high engine load when parked and also while coasting down the highway? It was doing something weird with the DPF for sure. You don&#039;t just hit 1100° idling or coasting otherwise. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote><br /> I agree the EGT alone would indicate regen (active or passive); however, the truck wasn&#039;t reporting anything else indicating you were in an active regen and you weren&#039;t towing so it wasn&#039;t passive. All the other data suggests you we&#039;re not in regen. <br /> <br /> That&#039;s why I wonder if something was dragging the engine down, or there was something else going on.</div>
 
<div class="bbWrapper">I&#039;m happy to report that I&#039;m coming up on 5,000 miles and I&#039;ve only had 24-hour scheduled regens. I&#039;m probably a good stress test... between RV trips, this is my daily driver. Unfortunately, I&#039;ve been forced to idle longer waiting for my kid at school pickup and such. It&#039;s not ideal but the truck is handling it perfectly. Only on one cycle did I see the EVIC get to 30%. I&#039;m currently at 18 hours since last regen (~350 miles) and I&#039;m at 10%.<br /> <br /> We&#039;re going on a trip with the camper in a week and I&#039;m hoping to time the regen to happen while towing with 6400D in the tank!</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 16713" data-quote="AH64ID" data-source="post: 355209" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355209" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355209">AH64ID said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> I agree the EGT alone would indicate regen (active or passive); however, the truck wasn&#039;t reporting anything else indicating you were in an active regen and you weren&#039;t towing so it wasn&#039;t passive. All the other data suggests you we&#039;re not in regen. <br /> <br /> That&#039;s why I wonder if something was dragging the engine down, or there was something else going on. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>With this new aftertreatment arrangement on the &#039;25&#039;s I wonder if they are doing some small in cylinder dosing to get the exhaust temp up in the SCR for more efficient operation?</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 50240" data-quote="PyroJoe" data-source="post: 355187" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355187" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355187">PyroJoe said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> How in the world would I have high engine load when parked and also while coasting down the highway? It was doing something weird with the DPF for sure. You don&#039;t just hit 1100° idling or coasting otherwise. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>Agreed. I&#039;m not always watching it but I&#039;ve never noticed a high temp like that outside of an active regen. I&#039;m just using my phone with OBDLink to monitor so it&#039;s not always open.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 20252" data-quote="superjoe83" data-source="post: 355216" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355216" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355216">superjoe83 said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> With this new aftertreatment arrangement on the &#039;25&#039;s I wonder if they are doing some small in cylinder dosing to get the exhaust temp up in the SCR for more efficient operation? </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote><br /> That would completely defeat the purpose of a seventh injector. The SCR only needs around 350°F</div>
 
<div class="bbWrapper">I don&#039;t remember where I saw it, but I found some Stellantis literature the other night that said after a truck as idled or driven at a low enough RPM for a certain amount of time (I think it said 1 hour), the idle would raise to 900 RPM and you&#039;d notice a lack of WOT power. Maybe this is what I experienced. But again, my DPF gauge didn&#039;t drop after this cycle completed, nor did my trigger %.</div>
 
<div class="bbWrapper">Were you idling for an hour? Rpms go to 900? <br /> <br /> That used to be called, and might still be, net zero idling. It’s not technically a regen but rather an idle mode to reduce emissions and soot buildup at idle only, such as in park. It shouldn’t happen in gear.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 16713" data-quote="AH64ID" data-source="post: 355235" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355235" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355235">AH64ID said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> Were you idling for an hour? Rpms go to 900?<br /> <br /> That used to be called, and might still be, net zero idling. It’s not technically a regen but rather an idle mode to reduce emissions and soot buildup at idle only, such as in park. It shouldn’t happen in gear. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>I didn&#039;t specifically look at RPM, but I know it stopped doing whatever it was in Park as I previously mentioned. But it would do it in gear and in neutral, stopped or moving, foot on the brake or not.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 50240" data-quote="PyroJoe" data-source="post: 355236" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355236" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355236">PyroJoe said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> I didn&#039;t specifically look at RPM, but I know it stopped doing whatever it was in Park as I previously mentioned. But it would do it in gear and in neutral, stopped or moving, foot on the brake or not. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote><br /> How long had you been stationary when it started?</div>
 
<div class="bbWrapper">I don&#039;t really want to say as my memory is a big foggy, but I believe I had to drive about 5 miles before it&#039;d start showing this behavior. It&#039;s been over a week now with lots of miles logged since then, so I&#039;m not positive.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 50240" data-quote="PyroJoe" data-source="post: 355238" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355238" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355238">PyroJoe said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> I don&#039;t really want to say as my memory is a big foggy, but I believe I had to drive about 5 miles before it&#039;d start showing this behavior. It&#039;s been over a week now with lots of miles logged since then, so I&#039;m not positive. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote><br /> Unless it took you a couple hours to go those 5 miles that does not sound like the net zero behavior, but if it was a very slow drive, there could be new strategy for net zero idling with the seventh injector. But that doesn’t explain why it went away in P</div>
 
<div class="bbWrapper">They didn&#039;t elaborate on whether it had to be 1 hour of idling all at once without stopping or 1 hour accumulated over a period of time and starts/stops. I certainly hit that hour of idle within a week&#039;s time, but never all at once before moving again.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 16713" data-quote="AH64ID" data-source="post: 355219" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355219" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355219">AH64ID said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> That would completely defeat the purpose of a seventh injector. The SCR only needs around 350°F </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote>Please keep in mind that 7-th injector is just before DPF&#039;s DOC. First DOC - mounted right after turbo outlet does not have it&#039;s own injector. It was shown - even in this thread that this first DOC is activated sometimes and there is no other way to heat it up different than in cylinder dosing.</div>
 
<div class="bbWrapper"><blockquote data-attributes="member: 51892" data-quote="AndyRoos" data-source="post: 355262" class="bbCodeBlock bbCodeBlock--expandable bbCodeBlock--quote js-expandWatch"> <div class="bbCodeBlock-title"> <a href="/forum/goto/post?id=355262" class="bbCodeBlock-sourceJump" rel="nofollow" data-xf-click="attribution" data-content-selector="#post-355262">AndyRoos said:</a> </div> <div class="bbCodeBlock-content"> <div class="bbCodeBlock-expandContent js-expandContent "> Please keep in mind that 7-th injector is just before DPF&#039;s DOC. First DOC - mounted right after turbo outlet does not have it&#039;s own injector. It was shown - even in this thread that this first DOC is activated sometimes and there is no other way to heat it up different than in cylinder dosing. </div> <div class="bbCodeBlock-expandLink js-expandLink"><a role="button" tabindex="0">Click to expand...</a></div> </div> </blockquote><br /> SCR has not ever needed or used in-cylinder dosing, why would they start now? Exhaust temps from driving are sufficient to let the SCR reduce NOx with DEF. <br /> <br /> Adding in-cylinder dosing for the SCR, when it’s closer to the engine, would be the opposite of what they are trying to accomplish with the 7th injector. That’s the point.</div>
 
You must log in or register to reply here.
Back
Top