What's my exhaust doing?

[Alphonse]

What are you using to monitor active regeneration?

Edge Insight CTS2

 

[Newsa]

The 4th gen trucks can see a regen as low as 800 degrees from my experience while monitoring realtime with the factory tools

You're talking active regen? Passive shouldn't show on any monitor, should it? I thought with passive, it was only hot exhaust and the truck didn't have to do anything to create that hot exhaust?

Or are you comparing DPF pressures (or does the truck compare DPF pressures) to signal passive regen.?

 

[Alphonse]

You're talking active regen? Passive shouldn't show on any monitor, should it? I thought with passive, it was only hot exhaust and the truck didn't have to do anything to create that hot exhaust?

Or are you comparing DPF pressures (or does the truck compare DPF pressures) to signal passive regen.?

With a monitor and via the CAN Bus, you can watch DPF pressure drop (pressure drop across the filter). This is a leading indicator of much soot is in the filter which is impeding exhaust flow. It is this pressure drop measurement that the Control Module watches, likely coupled with some other indicators, and triggers an active regeneration.

From articles written by Joe Donnelly and confirmed by me personally monitoring the "goings-on" with my truck via the Edge Insight CTS2, it appears that an exhaust gas temperature of 800F or higher is adequate for passive regeneration over time. In other words, run it loaded and you will likely see very little active regeneration going on.

Joe Donnelly has written a nice article in the latest edition (#91) of the TDR Magazine which touches this topic.

 

[AH64ID]

You're talking active regen? Passive shouldn't show on any monitor, should it? I thought with passive, it was only hot exhaust and the truck didn't have to do anything to create that hot exhaust?

Or are you comparing DPF pressures (or does the truck compare DPF pressures) to signal passive regen.?

The DPF doesn't care if it's active or passive, all it cares about it temperature.

With monitors you can watch the soot decrease, and based on other OBDII outputs you can determine if it's active or passive.

 

[gsbrockman]

From articles written by Joe Donnelly and confirmed by me personally monitoring the "goings-on" with my truck via the Edge Insight CTS2, it appears that an exhaust gas temperature of 800F or higher is adequate for passive regeneration over time. In other words, run it loaded and you will likely see very little active regeneration going on.

Joe Donnelly has written a nice article in the latest edition (#91) of the TDR Magazine which touches this topic.

Thanks for the confirmation on this. There's been so many "haters" (2007.5 through 2012 truck owners) that have stated on Forum A, B, C, D, and E that the 2013.5 & up trucks will never adequately passive regen, will need 1200*F (if not more) to passive regen, dilute oil due to so many active regens, get the same crappy fuel economy, and need constant oil changes (all of which is incorrect information).

I'm at 134,760 miles, 208 idle hours, and 2,516 drive hours. The only time I suspect my truck is in a re-gen is when I'm at a truck stop getting fuel and hear the DEF system ticking away at a more rapid pace than normal.

 

[AH64ID]

Don't forget that 800°F in the DPF is going to be 1,000°+ at the manifold which is not generally achieved under normal driving even with the 13+ programming; however, there is likely more to the story. I don't recall the 13+ having a pyro probe pre-turbo, correct?

The design of the DPF for 2013 didn't really change all that much, just the rest of the emissions which benefits the DPF. DEF changed the EGR requirements but not the DPF requirements. I have seen some 4th gen vs 3rd gen DPF comments that aren't tied to MY12 vs MY13, was there a DPF change for MY10??

A big benefit for the 13+ trucks is that the DPF is closer to the engine and the exhaust only has 1 other emissions device to go thru, this means higher DPF temps for the same EGT.

SCR/DEF specifically target the NOx and are very effective at it. What that means is that programming can allow for more NOx to be built during combustion which is a efficient combustion. A more efficient combustion produces less soot/more power on less fuel.

The DOC may have also changed for MY13 but I am not sure and the same with removal of the NOx absorber may have improved passive regen efficiency. That being said the DOC likely changed due to the EGR change and that also likely improved the DPF passive regen abilities.

Since DEF is used for SCR and is post-DPF I am not sure if there is a correlation between the two or not. There might be, but DEF is not used for DPF regeneration.

Things were so much simplier for the 03-04 trucks!! If we could only run with the emissions standards of 1989 with the electronic controls of 2016.


In doing some additional reading on regen I found a good ppt slide on the ISX. It appears the DPF on the ISX will do some from of regen with temps as low as 601°F... that's pretty good!!!

 

[kthaxton]

Since DEF is used for SCR and is post-DPF I am not sure if there is a correlation between the two or not. There might be, but DEF is not used for DPF regeneration.

I think what he means is with higher fuel usage (because of the regen) results in higher DEF usage.

 

[Alphonse]

Don't forget that 800°F in the DPF is going to be 1,000°+ at the manifold which is not generally achieved under normal driving even with the 13+ programming; however, there is likely more to the story. I don't recall the 13+ having a pyro probe pre-turbo, correct?

The design of the DPF for 2013 didn't really change all that much, just the rest of the emissions which benefits the DPF. DEF changed the EGR requirements but not the DPF requirements. I have seen some 4th gen vs 3rd gen DPF comments that aren't tied to MY12 vs MY13, was there a DPF change for MY10??

A big benefit for the 13+ trucks is that the DPF is closer to the engine and the exhaust only has 1 other emissions device to go thru, this means higher DPF temps for the same EGT.

SCR/DEF specifically target the NOx and are very effective at it. What that means is that programming can allow for more NOx to be built during combustion which is a efficient combustion. A more efficient combustion produces less soot/more power on less fuel.

The DOC may have also changed for MY13 but I am not sure and the same with removal of the NOx absorber may have improved passive regen efficiency. That being said the DOC likely changed due to the EGR change and that also likely improved the DPF passive regen abilities.

Since DEF is used for SCR and is post-DPF I am not sure if there is a correlation between the two or not. There might be, but DEF is not used for DPF regeneration.

Things were so much simplier for the 03-04 trucks!! If we could only run with the emissions standards of 1989 with the electronic controls of 2016.


In doing some additional reading on regen I found a good ppt slide on the ISX. It appears the DPF on the ISX will do some from of regen with temps as low as 601°F... that's pretty good!!!

Yes, the DPF is close coupled to the DOC. When the DOC is hard at work it generates additional heat via oxidation. So it will add heat to the exhaust stream and particularly when the timing and fuel dosing is done to generate an active regeneration of the DPF.

You are correct there is no manifold pyrometer. Some folks add them. Edge sells a kit for that purpose that will communicate with the Insight CTS2. I studied adding one when I put the Insight on mine. After evaluation, I decided against it since I saw no need for it and there's risk of getting crap in the turbo by drilling and tapping the manifold for the probe. One could remove the manifold for the drilling and tapping but that is a huge amount of work and I am sure it would give FCA pause if there were ever a warranty issue.

Yes, there is a temperature drop across the turbo and your pointer here that there's a difference before and after the turbo in temps is spot on. The turbo is doing work and it accomplishes that by converting heat into work. Therefore there is a temperature drop across the turbo, particularly when it is doing a lot of work. I did some looking a couple of months ago and found lots of data on temperature drops across turbos but not for the Cummins layout we have. I did find a Joe Donnelly's article in TDR #85, page 78 that was helpful. Joe's rule of thumb to get manifold temperature from the post-turbo temperature is: "add 10° for every psi of boost shown on your boost gauge." So if your boost is 20 psi and your temperature post-turbo is 800, then you'd see 1000F at the manifold. A solid boost of 20 psi is pretty rare watching my truck. Perhaps I have been being too kind to it?

Meanwhile I have seen 800F after the Catalyst and that is where I now believe the passive regeneration works well evidenced by the lack of active regenerations seen.

Regarding correlation of DEF use during DPF regeneration, I have wondered what happens to NOx production during an Active Regeneration. Obviously the temperatures rise and one could surmise that NOx does goes up, I do not know. If this were the case, the DEF dosing would be occurring as well. Time for more studies!

By the way, was the reference in the ISX document 600 degrees Fahrenheit or Celsius?

 

[AH64ID]

That 10° per 1 psi is fairly accurate on my 05 with a GTX3782R Turbo, but I hadn't ever thought of it until you just mentioned it!!


http://abc-companies.com/bundles/abccompaniescms/pdf/generic_pdfs/Cummins ISX.pdf

 

[Alphonse]

Thanks John for the ISX slide pack and yes, it says 601 degrees F for passive regeneration. That is quite interesting. Of course there is a slight difference in this Cummins used for a bus engine and the one that is in our beloved trucks but it is still a very interesting reference number.

 

[AH64ID]

Yes the application, and thus average load and EGT, are different; however, for the most part a DPF is a DPF.

 

[Newsa]

Thanks John for the ISX slide pack and yes, it says 601 degrees F for passive regeneration. That is quite interesting. Of course there is a slight difference in this Cummins used for a bus engine and the one that is in our beloved trucks but it is still a very interesting reference number.

At 600 degrees, does that mean a long highway drive could partially/passively regen the DPF?

 

[Alphonse]

I wish I knew the absolute answer. I do not but I have been searching.

The 601F number comes from a Cummins application used in buses. As John pointed out, can it be that much different for our DPFs?

I have noticed that highway miles tend seem to avoid regens.

Who has a good contact with RAM engineering so we can get a solid answer on this?

 

[Newsa]

I wish I knew the absolute answer. I do not but I have been searching.

The 601F number comes from a Cummins application used in buses. As John pointed out, can it be that much different for our DPFs?

I have noticed that highway miles tend seem to avoid regens.

Who has a good contact with RAM engineering so we can get a solid answer on this?

May madness? If FCA sends representatives? An honest answer about if driving unloaded on a highway can partially regen a 4th gen Ram DPF would answer alot of questions. A friend of mine owned a 1997 12 valve and never towed anything. He didn't have DPF issues. But then again, I don't know if his was deleted or if his 12 valve never had a DPF.

 

[Mingoglia]

May madness? If FCA sends representatives? An honest answer about if driving unloaded on a highway can partially regen a 4th gen Ram DPF would answer alot of questions. A friend of mine owned a 1997 12 valve and never towed anything. He didn't have DPF issues. But then again, I don't know if his was deleted or if his 12 valve never had a DPF.

Yeah, the DPF wasn't introduced until the third gen trucks... I believe around 2007? Gone are the days of rolling coal, and now our trucks smell like propane grills at the exhaust, instead of a "real" diesel. I suppose "real diesel", is now the propane smell, or maybe I'm over-analyzing this.

 

[RVTRKN]

Any auto/trucks with Diesel engines manufactured after Jan-1-2007 must have a DPF. That's why there is a 5.9 and a 6.7 CTD in a 2007 Ram and a 2007.5 has the 6.7.


2007 C&C's had the first 6.7 with DPF's and was available in mid year 2006, but have slightly less restrictive emissions.

 

[AH64ID]

No 5.9 ever had a DPF is a good way to look at it too.

At 600 degrees, does that mean a long highway drive could partially/passively regen the DPF?

I read it as at 601° the DPF can start to self clean. The big question is does it clean faster than it gets plugged? My guess it at 601° it just slows the plugging, but at something like 1200° it probably can regen faster than it plugs.

Make sense?

Any auto/trucks with Diesel engines manufactured after Jan-1-2007 must have a DPF. That's why there is a 5.9 and a 6.7 CTD in a 2007 Ram and a 2007.5 has the 6.7.


2007 C&C's had the first 6.7 with DPF's and was available in mid year 2006, but have slightly less restrictive emissions.

Didn't the C&C's for MY07-09 meet the 2007 emissions and the pickups for MY07.5-09 meet the 2010 emissions? I think that is why the C&C's were less restrictive in 2007 and had a change in 2010 whereas the pickups were basically unchanged from 07.5-12 even thou the emissions got more restrictive in 2010.

 

[RVTRKN]

Not sure on the 2010 and newer C&C but the 07 thru 09 before DEF is less restrictive. It was not the same as an 07.5 thru 2012.

 

[RVTRKN]

I believe that's the reason, because the C&C only met the 2007 thru 2009 emissions.