24 Hour Regens No Longer Happen

[John Jensen]

And if a regen happens mid 24 hours, that would reset the 24 hours, correct?

No, it does not reset the 24 hours, and it will still regen on the 24-hour mark.

 

[AH64ID]

For the first time in over 100 hours my DPF gauge moved off zero today. It’s at 12.5%. The CTS3 shows 89%, which correlates to the 21 hours since my last regen. Idle DPF pressure is 0.06-0.07psi.

No, it does not reset the 24 hours, and it will still regen on the 24-hour mark.

It sure should reset it, just like a manual regen resets the 24 hour timer.

The engine has to regen every 24 hours, at the longest. Any active regen is supposed to reset the 24 hour timer.

 

[John Jensen]

It sure should reset it, just like a manual regen resets the 24 hour timer.

The engine has to regen every 24 hours, at the longest. Any active regen is supposed to reset the 24 hour timer.

I was told differently. That said, I respect your knowledge, you are usually right on.
I'll take your answer and stand corrected.
That also explains what I thought strange, a regen lapsed hours changed following the 15 hour regen I mentioned above.
And, apologize to Will_T for misleading you.
Thanks

 

[Will_T]

Do you have the DPF diff pressure and DPF percentage PIDs turned on on your iDash? If not I would turn them on. The diff should have a reading .1psi or higher and should go up as you request more power. The percentage PID should read something under 100%. Normal regen is at 100% if you have not gotten to the 24hrs.

It's the delta pressure, not the outlet pressure (DPFDP1). As for finding it on your iDash, make sure the firmware is up to date and look under look under different categories (I have found ones you think should be emissions but is under temp or pressure only).

Thanks - I found it, DPFDP1, in the Pressure category as suggested. It reads .1psi and when increasing the rpm goes up a bit.

Interestingly, the DPFRG% was at 96% when I shut off the truck yesterday. When I started it just now, it shows 99%. So, it went from 96 to 99% overnight without the truck being started. Does that make sense that it would not go through 97 and 98% but jump from 96 to 99% with no engine run time?

 

[Jay P]

Looks like things are working like they are supposed to and it should regen pretty soon.

 

[Jay P]

Interestingly, the DPFRG% was at 96% when I shut off the truck yesterday. When I started it just now, it shows 99%. So, it went from 96 to 99% overnight without the truck being started. Does that make sense that it would not go through 97 and 98% but jump from 96 to 99% with no engine run time?

Those percentage numbers are calculated so it can change when you shut the truck off and restart it (mine does it all the time).

 

[Will_T]

I took the truck for a drive and the DPFRG% quickly went to 100%. (Photo one below). It stayed there for about 5 minutes and then the regen triggered. At the start of the regen, engine hours were 170 and the DPFRG% switched to 36% as seen in photo two. It then slowly climbed over the first few minutes of regen until it reached 49% where it stayed for the rest of the regen, (#3). When the regen switched off, the DPFRG changed to 38%, then immediately changed again to 45%. I made a stop and when I restarted the truck, it must have recalculated because the DPFRG is now at 9%.

So, I think it is all working as it should. There must have been something about the two dealer visits I had in over the past 8 months that messed up the 24-hour timer and then, because the soot load was low, it never called for a regen. That is why it the engine hours went from 120 to 170 between regens when I was expecting to see regens at 144 and 168 hours. Now, assuming no dealer visits in the meantime, the next regen should occur at 194 hours.

By the way, you can kind of see in the photos what the DPF Delta Pressure is doing now that I have the DPFDP1 PID displaying. It sits at 0.0 or 0.1 when idling, then on my mostly highway drive it varied between 0.3 and 0.9. So I guess that is as it should be also.

Thanks for all the input. I think this thread actually ended up with a lot of good information for anyone who may want to know more about this or who has an iDash or CTS3 and just likes monitoring things.

 

[AH64ID]

I took the truck for a drive and the DPFRG% quickly went to 100%. (Photo one below). It stayed there for about 5 minutes and then the regen triggered. At the start of the regen, engine hours were 170 and the DPFRG% switched to 36% as seen in photo two. It then slowly climbed over the first few minutes of regen until it reached 49% where it stayed for the rest of the regen, (#3). When the regen switched off, the DPFRG changed to 38%, then immediately changed again to 45%. I made a stop and when I restarted the truck, it must have recalculated because the DPFRG is now at 9%.

So, I think it is all working as it should. There must have been something about the two dealer visits I had in over the past 8 months that messed up the 24-hour timer and then, because the soot load was low, it never called for a regen. That is why it the engine hours went from 120 to 170 between regens when I was expecting to see regens at 144 and 168 hours. Now, assuming no dealer visits in the meantime, the next regen should occur at 194 hours.

By the way, you can kind of see in the photos what the DPF Delta Pressure is doing now that I have the DPFDP1 PID displaying. It sits at 0.0 or 0.1 when idling, then on my mostly highway drive it varied between 0.3 and 0.9. So I guess that is as it should be also.

Thanks for all the input. I think this thread actually ended up with a lot of good information for anyone who may want to know more about this or who has an iDash or CTS3 and just likes monitoring things.

View attachment 54483

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That’s how my DPF % works as well during and immediately following an active regen.

If the iDash had more digits you would likely see DPF pressure closer to 0.01 after an active regen.

 

[Will_T]

View attachment 54479

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Here is what I have on my iDash.

Jay

@Jay P - I monitor EGT1, 2, and 3. I see you don't have EGT1. Is there a reason why monitoring EGT1 is not necessary? I thought that was the one right after the turbo so if you want to avoid shutting down the engine when the turbo is too hot, that is the one to check. I don't know where EGT2 is located so maybe that gives you very similar info. I just put all 3 on my iDash since I had space. But if I need to create a spot for another PID, should I knock out EGT1 or 2? Well, I suppose I could just get a 2nd iDash and not have to think about that!

 

[Will_T]

That’s how my DPF % works as well during and immediately following an active regen.

If the iDash had more digits you would likely see DPF pressure closer to 0.01 after an active regen.

Thanks! Is it normal to see that DPF pressure as high as .8 or .9 when under load on the highway? (Like going up a hill.)

 

[AH64ID]

I monitor EGT 1 and EGT3 on my main page (CTS3) and 1-5 on my secondary page.

EGT 2 is DOC outlet and EGT 3 is DPF outlet.

I like to watch EGT1 as it’s a good post-turbo pyro reading, and EGT3 to see how much passive regen I’m getting most the time.

I don’t feel the need to watch EGT2 under non-active regen, and really only rarely glance at it even in regen.

Thanks! Is it normal to see that DPF pressure as high as .8 or .9 when under load on the highway? (Like going up a hill.)

Yes, it will even go above 1.0 (I want to say I’ve seen ~1.5) towing heavy up a steep grade.

 

[John Jensen]

I monitor EGT 1 and EGT3 on my main page (CTS3) and 1-5 on my secondary page.

EGT 2 is DOC outlet and EGT 3 is DPF outlet.

I like to watch EGT1 as it’s a good post-turbo pyro reading, and EGT3 to see how much passive regen I’m getting most the time.

I don’t feel the need to watch EGT2 under non-active regen, and really only rarely glance at it even in regen.



Yes, it will even go above 1.0 (I want to say I’ve seen ~1.5) towing heavy up a steep grade.

I try to monitor all I need on one page. I change between EGT 1 & 2, can't decide which I like best, lean towards 2

 

[Will_T]

If the iDash had more digits you would likely see DPF pressure closer to 0.01 after an active regen.

That is interesting also as for a short time after the regen it was reading 0.0 and I thought something was off. But maybe it reads 0.0 when it is under .04.

 

[AH64ID]

I try to monitor all I need on one page. I change between EGT 1 & 2, can't decide which I like best, lean towards 2View attachment 54493

I don’t find 2 telling me anything useful outside of an active regen.

That’s my secondary page, stuff that I want data from occasionally but not day to day ops.

 

[joshuaeb09]

Thanks! Is it normal to see that DPF pressure as high as .8 or .9 when under load on the highway? (Like going up a hill.)

Yes, it will even go above 1.0 (I want to say I’ve seen ~1.5) towing heavy up a steep grade.

That is where I've seen a measurable benefit from the Magnaflow filterback (other than it looks a lot better on a non-night edition laramie having that chrome intercooled tip). Under light loads I couldn't measure any differences, but pulling some of the grades to be found in the Tx hill country I will see a drop from .8 - .9 to closer to .4 - .5. Really only installed it for the look and having an intercooled tip, but it's nice to see some minor tangible benefit.

 

[John Jensen]

View attachment 54479

View attachment 54480

@Jay P - I monitor EGT1, 2, and 3. I see you don't have EGT1. Is there a reason why monitoring EGT1 is not necessary? I thought that was the one right after the turbo so if you want to avoid shutting down the engine when the turbo is too hot, that is the one to check. I don't know where EGT2 is located so maybe that gives you very similar info. I just put all 3 on my iDash since I had space. But if I need to create a spot for another PID, should I knock out EGT1 or 2? Well, I suppose I could just get a 2nd iDash and not have to think about that!

Will,
This will give you the EGT sensor locations. A good diagram of the emissions system.

 

[Jay P]

View attachment 54479

View attachment 54480

@Jay P - I monitor EGT1, 2, and 3. I see you don't have EGT1. Is there a reason why monitoring EGT1 is not necessary? I thought that was the one right after the turbo so if you want to avoid shutting down the engine when the turbo is too hot, that is the one to check. I don't know where EGT2 is located so maybe that gives you very similar info. I just put all 3 on my iDash since I had space. But if I need to create a spot for another PID, should I knock out EGT1 or 2? Well, I suppose I could just get a 2nd iDash and not have to think about that!

Looks like AH64ID already answered this and John Jensen put up a good pic of where the temp probes are. I have a separate iDash page that has all the EGT temps on it. The iDash has a bunch of different pages and you change pages by pushing the left arrow on the iDash.

Jay

 

[AH64ID]

That is where I've seen a measurable benefit from the Magnaflow filterback (other than it looks a lot better on a non-night edition laramie having that chrome intercooled tip). Under light loads I couldn't measure any differences, but pulling some of the grades to be found in the Tx hill country I will see a drop from .8 - .9 to closer to .4 - .5. Really only installed it for the look and having an intercooled tip, but it's nice to see some minor tangible benefit.

I’ve been thinking about this, and I’m not sure you would really see any benefit from it on DPF pressure readings. It’s not actually a filter back exhaust, it’s a SCR back exhaust.

The pressure reading is delta pressure across the DPF, not actual back pressure. The higher the flow the more delta pressure, even on a clean DPF. The SCR is also between the DPF and the new exhaust, and that will provide restriction to the exhaust flow thru the DPF over the potential gains from the new 5” tailpipe that is post SCR.

 

[joshuaeb09]

I’ve been thinking about this, and I’m not sure you would really see any benefit from it on DPF pressure readings. It’s not actually a filter back exhaust, it’s a SCR back exhaust.

The pressure reading is delta pressure across the DPF, not actual back pressure. The higher the flow the more delta pressure, even on a clean DPF. The SCR is also between the DPF and the new exhaust, and that will provide restriction to the exhaust flow thru the DPF over the potential gains from the new 5” tailpipe that is post SCR.

My OE tailpipe had pretty crappy bends in it, The kind that I could see becoming restrictions at higher flow volumes. In some areas it was down to about 2.5" or maybe a touch smaller just measuring OD. Just noting what I saw from the, lets call it emission back, setup. Like I mentioned I didn't buy it for any sort of performance gains, just wanted the better looking SS with the Chrome tip to dress up the Laramie. Any other benefits are just a bonus imo.

 

[BlueOx2500]

I just wish info on this 24 engine hour regen was in the truck's manual. I feel like I bought a B737MAX.

My truck just recently overshot the 24hr by 2-3 hrs...small number, who knows why...mostly because not enough info is in the manual.