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  #1  
Old 09-05-2015, 11:58 AM
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Yesterday I was heading out from the city on a roadtrip and I noticed an interesting phenomenon. The DPF soot level started out around 52% and within three miles of stop and go driving it got up to 63%. Rather surprising in terms of velocity, but when I hit the open road it rapidly rebounded to about 53% over a period of a few minutes. There was no regen active at this time (i.e. it was in Regen Mode 0 the whole time... besides, regens drop the reported soot level from 100% down to 9.4%).

My hypothesis was that this transient spike in *reported* soot level was due to DPF backpressure that reduced once the vehicle was operating at a constant RPM on the freeway (mumble, mumble, hand wave). I'm not entirely satisfied with that conjecture. Does anyone else have plausible hypotheses to share?

Overall, the trip was rather crappy in terms of fuel economy... I had approximately 9.1 L/100 km yesterday vs. 7.6 L/100 km for this same trip last week.

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  #2  
Old 09-05-2015, 04:15 PM
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Re: DPF soot level

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Originally Posted by Roadkill View Post
Yesterday I was heading out from the city on a roadtrip and I noticed an interesting phenomenon. The DPF soot level started out around 52% and within three miles of stop and go driving it got up to 63%. Rather surprising in terms of velocity, but when I hit the open road it rapidly rebounded to about 53% over a period of a few minutes. There was no regen active at this time (i.e. it was in Regen Mode 0 the whole time... besides, regens drop the reported soot level from 100% down to 9.4%).

My hypothesis was that this transient spike in *reported* soot level was due to DPF backpressure that reduced once the vehicle was operating at a constant RPM on the freeway (mumble, mumble, hand wave). I'm not entirely satisfied with that conjecture. Does anyone else have plausible hypotheses to share?

Overall, the trip was rather crappy in terms of fuel economy... I had approximately 9.1 L/100 km yesterday vs. 7.6 L/100 km for this same trip last week.
I'm going to say you had some passive regeneration going on once you hit the open road.

My Edge CTS will often indicate a reduction in soot level at highway speeds especially when carrying a load with my Ram 1500.

This does not apply to your situation, but a partial active regen will partially reduce the soot level and you might see 45% instead of the 9.4% you see after a completed regen..
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Old 09-05-2015, 04:31 PM
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Re: DPF soot level

I have also noticed since the latest ECM update that all my regens are advertised in the EVIC. Previous to the update, never saw any visual notice that the vehicle is in the middle of a regen... is that a good thing or bad thing? New CAT 1 month ago for P20EE....
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Old 09-05-2015, 06:24 PM
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Originally Posted by 2012 Summit View Post
This does not apply to your situation, but a partial active regen will partially reduce the soot level and you might see 45% instead of the 9.4% you see after a completed regen..
Right. From what I understand, passive regen on our platform requires quite a bit of effort to achieve (e.g. towing). Also, I'd expect the regen PID to fire to mode 2 during a passive regen rather than remaining 0. Additionally my cat temps never got above 375 C during the stop and go (or later on the highway). If passive regen can happen at low cat temps then they should do that all the time!

Quote:
Originally Posted by Stbentoak View Post
I have also noticed since the latest ECM update that all my regens are advertised in the EVIC.
Interesting. I've never seen a regen message in EVIC, and the firmware on my '14 was updated in early June 2015.
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Old 09-06-2015, 04:39 PM
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I think I finally understand why I have seen my Jeep drive hundreds of miles on the highway with the DPF soot level reported at 100% the whole time, but no regen kicks in.

The reason? The DPF soot level reported over OBD-II is not only *not* the true soot level, but it also exhibits hysteresis. The soot level will report a value until it gets to 66%, whereupon it will jump to 100% and stay there until a regen burns the DPF down. However, during a regen process the DPF will continue to report as 100%.

The other day I had an aborted normal regen. Regens typically take 10 minutes or so, and it probably burned about 8 minutes before it aborted. Subsequently the DPF soot level was still reported to be 100%. Obviously that wasn't true after a regen burn that was 4/5 done, but due to the hysteresis it was still reporting that regardless. I drove several hundred miles and finally got into another regen that completed normally. After the regen, the reported soot level dropped back to 9.8% as usual.

Just to reiterate: I am talking about normal regens that can only be detected by OBD PIDs or the $50 GDE add-on feature... *not* the emergency "drive at highway speeds" regen messages some owners see on their EVIC. I've never encountered one of those.
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Old 09-06-2015, 07:06 PM
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Re: DPF soot level

I have seen my soot level jump a few times. Normally shortly after cold starting and driving aggressively. My guess was that the more aggressive driving with higher revs being held slightly changed the back pressure levels compared to normal driving.

It jumped from ~60% to ~80% and I got the evic message 'regen in process, continue driving'.

I have the export model, so probably different programing, but I've never seen 100% reading. The reading will normally remain at the level it was when the regen began, and update when it finishes.
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Old 09-06-2015, 07:32 PM
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Quote:
Originally Posted by Benn0 View Post
I have seen my soot level jump a few times. Normally shortly after cold starting and driving aggressively. My guess was that the more aggressive driving with higher revs being held slightly changed the back pressure levels compared to normal driving.
That seems much like my experience.

Quote:
It jumped from ~60% to ~80% and I got the evic message 'regen in process, continue driving'.
I've never seen any similar message on my EVIC.

Quote:
I have the export model, so probably different programing, but I've never seen 100% reading.
Yes, the export model is different. Your models apparently don't report regen status via OBD PID either. I don't think the NA models ever report a DPF soot level higher than 66% without immediately jumping to 100%.
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Old 09-06-2015, 07:42 PM
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Re: DPF soot level

Quote:
Originally Posted by Roadkill View Post
I've never seen any similar message on my EVIC.
Yeah, I've only seen it that once when soot level got over 80%.
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Old 09-06-2015, 08:31 PM
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Quote:
Originally Posted by Benn0 View Post
Yeah, I've only seen it that once when soot level got over 80%.
That part is probably the same on the NA model, but we have no way of knowing what our soot level is via the soot PID, once the value exceeds 66%. Somewhere in there is the real value... I'm sure WiTech has access to it.

Would be cool to hook up a logic analyzer to a WiTech pod to see what the real canbus commands are to access things like actual DPF soot value, transmission temp, fuel tank level, etc.
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Old 09-06-2015, 08:55 PM
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Re: DPF soot level

Quote:
Originally Posted by Roadkill View Post
I think I finally understand why I have seen my Jeep drive hundreds of miles on the highway with the DPF soot level reported at 100% the whole time, but no regen kicks in.

The reason? The DPF soot level reported over OBD-II is not only *not* the true soot level, but it also exhibits hysteresis. The soot level will report a value until it gets to 66%, whereupon it will jump to 100% and stay there until a regen burns the DPF down. However, during a regen process the DPF will continue to report as 100%.

The other day I had an aborted normal regen. Regens typically take 10 minutes or so, and it probably burned about 8 minutes before it aborted. Subsequently the DPF soot level was still reported to be 100%. Obviously that wasn't true after a regen burn that was 4/5 done, but due to the hysteresis it was still reporting that regardless. I drove several hundred miles and finally got into another regen that completed normally. After the regen, the reported soot level dropped back to 9.8% as usual.

Just to reiterate: I am talking about normal regens that can only be detected by OBD PIDs or the $50 GDE add-on feature... *not* the emergency "drive at highway speeds" regen messages some owners see on their EVIC. I've never encountered one of those.
I believe what you are seeing is a function (or malfunction) of your monitor. Do you use a scangauge? The scangauge does not report accurately. I monitor with the Edge CTS and it does not jump to 100%. After a partial regen it will display the current soot level. ie: 45% or whatever it happens to be.
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Old 09-07-2015, 12:02 AM
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Quote:
Originally Posted by 2012 Summit View Post
I monitor with the Edge CTS and it does not jump to 100%. After a partial regen it will display the current soot level. ie: 45% or whatever it happens to be.
Do you have a NA 2014 EcoDiesel?

I'm using the Torque app. I suppose I can double check the raw binary values dumped, but the behavior seems to match the spec:
Normalized Trigger for DPF Regen ($8B, byte C, min: 0%, max: 100 %, formula: 100/255 %, value: DPF_REGEN_PCT: xx)

DPF_REGEN_PCT shall indicate the normalized DPF loading, time, distance, drive cycles or other criteria before the next DPF regen where 0% means the DPF is clean (a complete regen just occurred) and 100% means the DPF is ready to be regenerated. When there are multiple criteria to trigger a regen, the one that is closest to triggering the regen shall be displayed.
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Old 09-07-2015, 07:49 AM
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Re: DPF soot level

Quote:
Originally Posted by Roadkill View Post
Do you have a NA 2014 EcoDiesel?

I'm using the Torque app. I suppose I can double check the raw binary values dumped, but the behavior seems to match the spec:
Normalized Trigger for DPF Regen ($8B, byte C, min: 0%, max: 100 %, formula: 100/255 %, value: DPF_REGEN_PCT: xx)

DPF_REGEN_PCT shall indicate the normalized DPF loading, time, distance, drive cycles or other criteria before the next DPF regen where 0% means the DPF is clean (a complete regen just occurred) and 100% means the DPF is ready to be regenerated. When there are multiple criteria to trigger a regen, the one that is closest to triggering the regen shall be displayed.
Yes, NA 2014 Ecodiesel. Here's a photo of regen in progress at 71% soot level.
Attached Images
File Type: jpg soot.jpg (164.2 KB, 70 views)
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