DEF, Regen questions

[Berrigan]

I am still learning about the newer trucks and have a few observations and questions.

When I purchased the 2016 it was cooler outside and I notice the truck regenerated about every 700 or so miles. Now that its hot outside I am not noticing regens any more. Maybe it is and I just don't see it. Is it possible that at higher outside temps the passive regen is enough to keep the system clean? ( I notice the regens by odor and instantaneous mpg drop)

My second question is about DEF usage. Does the system use DEF at all times the engine is running. In other words very small amounts are constantly being injected into the exhaust when ever the engine is running. Or does it inject periodically as needed during operating conditions that require it.


Lastly an observation. I arrived home on Sunday after a three hour freeway trip. The ambient temp was 115 when I pulled in the driveway. I got out and used my IR temp gun and scanned the DEF tank. The DEF was 137 degrees F. I assume the engineers take these DEF temp spikes into consideration when operation is in high temp environments and the life of the DEF is not affected to any large degree by these spikes. Any thoughts?

 

[Newsa]

I am still learning about the newer trucks and have a few observations and questions.

When I purchased the 2016 it was cooler outside and I notice the truck regenerated about every 700 or so miles. Now that its hot outside I am not noticing regens any more. Maybe it is and I just don't see it. Is it possible that at higher outside temps the passive regen is enough to keep the system clean? ( I notice the regens by odor and instantaneous mpg drop)

My second question is about DEF usage. Does the system use DEF at all times the engine is running. In other words very small amounts are constantly being injected into the exhaust when ever the engine is running. Or does it inject periodically as needed during operating conditions that require it.


Lastly an observation. I arrived home on Sunday after a three hour freeway trip. The ambient temp was 115 when I pulled in the driveway. I got out and used my IR temp gun and scanned the DEF tank. The DEF was 137 degrees F. I assume the engineers take these DEF temp spikes into consideration when operation is in high temp environments and the life of the DEF is not affected to any large degree by these spikes. Any thoughts?

1.) You will likely have fewer active regens in higher ambient temps

2) NOx is only created under high temp/high pressure. Def should only be injected after both the engine and Exhaust heat up. There are several temps sensors and at least one of those is in the exhaust. Def will only react like it is supposed to (with SCR catalyst) under high temps

3) Wouldn't worry to much about def degradation under high ambient temps. The DEF/SCR system will not be damaged by weak def. And the Ram (unlike other trucks) won't go into limp mode if the def is weak. It will give you warnings that it will go into limp mode. But won't do it unless something else is seriously wrong.
Some manufacturers will have their def pumps draw/spray more def when def is weak. But not sure if Ram does this.

 

[lakedaisy]

I live in FL and it's hotter than heck. My truck regens about every 600 miles. MPG drops from about 15 to about 13.5. I can sometimes smell it when I'm standing close to the truck after driving it.

 

[Newsa]

I live in FL and it's hotter than heck. My truck regens about every 600 miles. MPG drops from about 15 to about 13.5. I can sometimes smell it when I'm standing close to the truck after driving it.

Watch your oil level. If it starts rising on the dipstick, get an oil analysis or change it.




It feels hotter to us in Florida than it feels to the truck. I live in Miami and it's never been hotter than 99 degrees. That's a far cry from 115. We feel the humidity. The truck doesn't

 

[lakedaisy]

Why is that Newsa? What would make the oil level rise? I have about 2200 miles on the truck and I think it has regened about 3 or 4 times.

 

[Newsa]

I suspect fuel dilution of the oil. Fuel dilution adds volume to your fuel.

You can get an oil analysis done.

I change my oil every 6-7 active regens.

During active regen, the injectors add more fuel. Some of the fuel can end up diluting the fuel in the crankcase. Some have done oil analysis and noticed 5w- 40 being diluted to 5w 30 or thinner. The manual doesn't call for 5w 30, so if j see the oil going to the top of the plastic on the dipstick, i change it. The top of the plastic is well over the full mark.

 

[SnoKing]

I have had my 2015 9 months now and just short of 15K, and I have not notice when it goes through its active regens! I must be getting old! Maybe I am to busy with hands free calls, XM radio, and Nav to know about other events occurring. SNOKING

 

[Deleted member 995608]

I'm with Sno. Can't tell when it's regen-ing. No beeping, no flashing, no alerts whatsoever. I'm just shy of 10K and I've only had to add (1) 2.5 gallons of DEF since I took delivery in January.

 

[kthaxton]

I noticed regens on maybe 2-3 occasions within the first couple of months of ownership, I have not 'noticed' a regen in the last year or so.

Apparently, I don't watch my mileage enough to notice, I rarely watch my mileage in real time and with how much it fluctuates (in real time), I would never be able to conclude that it is using more fuel than normal.

 

[lakedaisy]

Okay. Oil level looks fine. Just below the full mark. The oil sure looks filthy for only 2.2k miles. My duramax I had for 14 years had new looking oil at 2k miles. I have oil and filter. May just go ahead an change oil early. I've only had the truck 4 months.

kthaxton. the mpg is one of the displays I've set on my DID. So it's always there near the speed. I can easily see when it goes into regen as milage drops 1-2 mpg

 

[kthaxton]

kthaxton. the mpg is one of the displays I've set on my DID. So it's always there near the speed. I can easily see when it goes into regen as milage drops 1-2 mpg

Yes, I can do the same thing (watch real time mileage on my screen). What I meant was I don't pay close enough attention to know what the exact mileage is on any given stretch of road under non-regen conditions to compare. I don't bother because on any particular stretch of road and throttle position, I can see mileage quickly drop with the slightest change in grade, (even those grades that aren't obvious), or throttle position. These variances make it seem like a futile attempt.

 

[lakedaisy]

I think we are referring to two different things. You are referring to the real time milage screen. I don't use that it seems pretty useless to me. I'm referring the the 6 settings that one can set to always display on the DID to monitor other things like oil temp, trans temp, AVG mpg, etc. I have the Avg mpg in one of the corners and can see my milage quickly go from around 15 or so mpg to 13.5 mpg and it stays at 13.5 or so (around town for quite a while) then jumps back up to around 15 or so when the regen is finished.

 

[kthaxton]

Ahh I see, but in my experience, that would be an even less reliable indicator (at least for me), I never see that mileage change much until I drive under different circumstances (i.e. all or mostly highway with little elevation change and towing). In fact, when I am towing, it takes quite a while for my average to start dropping.

More specifically....my daily commute to work is the only consistent drive I do. It has a lot of elevation gain and loss, both ways (I live in a mountain valley in Utah, and commute to another, higher mountain valley). If this is the only driving I do for a period of time, I never notice much change in my average mileage. However, when I drive down to the valley(s) (Salt Lake, Provo) my average goes up slightly, over time).

Once I hook up the trailer, my mileage starts to go down....but I still have to drive several miles (maybe 10-20?) before my average drops noticeably.

What I am getting at is that I don't think in my situation, I could ever use average mileage as a way to determine a regen, but I have heard you and others claim this. Perhaps it is just not possible for me to notice it by commuting where there is so much elevation change?

 

[kthaxton]

I suppose it is also possible that my regular commute provides enough passive regen that an active is not needed? Not sure, I just have never noticed a random loss of mileage with my typical commute.

 

[Newsa]

I only notice active regens when at idle at a stop sign/light or just above idle when tooling through town at constant speed. It makes alot more engine noise. It sounds like high idle with exhaust brake on.

 

[lakedaisy]

Ha! I'm only guessing that the truck is in active regen as the Avg mpg pretty quickly drops to the 13's then after a while it pretty quickly comes back up to upper 14's/lower 15's. What the heck do I know. Only what I read. I try to stay pretty close to what the owners manual tells me as there are so many on the diesel forms that talk like they know what they are saying when they really don't.

This truck is new to me. Unlike my Duramax which I owned forever and and pretty much knew everything about it. However, my Duramax didn't have any smog controls and was a breeze to work on. Now, my son's '15 Duramax has a totally filled engine compartment just like my Cummins. These new trucks have so many controls that I'll probably be doing very little work on it, except for general maintenance.

I've only smelt a burning smell outside my truck once. And it smelt like something was burning for sure. I checked under my truck to make sure it wasn't on fire. It wasn't. I've never hear any different sounds from the engine. If fact it's so damn quite that it's hard to tell it's a diesel. I actually preferred my old trucks diesel sound.

 

[kthaxton]

When I noticed a regen, I did not notice a burning smell, it was more of a raw fuel smell. I've heard a "burning smell" is typical of new trucks.

 

[Kirwin]

You can hear the DEF injector opening (clicking) on my truck. I pull in from off the interstate, stand by the passengers side rear door, about every second or 2 you can hear it. Click click click.

 

[Newsa]

I think the active regen programming is different for the manual transmission trucks. It appears to be dependent on speedometer speed. Or how long you have been stopped and idling. If the program thinks you are going to let out the clutch to start. Or if you depress the clutch to stop the louder engine noise stops. I can only hear the engine when it is actively regenerating. Would love to show you what I'm talking about with the engine noise. And maybe I will if you live in South Florida.

 

[kthaxton]

You can hear the DEF injector opening (clicking) on my truck. I pull in from off the interstate, stand by the passengers side rear door, about every second or 2 you can hear it. Click click click.

Do you suppose it is only clicking because it happens to be dosing more DEF than when it's not in regen?