An interesting regen situation...

[EDKtrans]

I have a situation here. Not sure but I think it could be a sign of a problem.

The truck is my 2008 CC 3500 6.7. Its got a bit over 370,000 miles on it and runs great. Its a hard working oil field hot shotting truck and has been since new. The exhaust system is completely stock and original, including the dpf.

From new the truck has had an Edge Insight monitor installed. For the most part its entertainment of a sort on long drives. I monitor regens while out there mostly just cause I can but I also end up sleeping in the truck and letting it idle for hours at a time so I like to know when the next regen will be coming up. For the entire life of the truck the time between regens has averaged something around 20 hours. Heavy loads on the trailer will extend this time, lots of low speed driving will shorten it. The longest time between regens in the past was a bit less than 40 hours on a very heavy, long drive from Denver to Laffayette, LA. I've now blown that previous record away.

At the moment, as reported by the Edge Insight its been over 60 hours since my last regen. My driving over that time has been with a moderate, quite normal load on my trailer driving roads in North Dakota that I drive often, doing pretty much what I always do, (including a rest stop idling the truck for about 6 hours) buying fuel at the same places I always buy it. On my way home, at a bit over 40 hours in I stopped at the dealership in Miles City, MT. to have them check it out. 40 hours plus since my last regen and they claimed I was at 8g soot load. They hadn't seen one go this long but hey, the soot load is low so don't worry about it! I got the same attitude from my normal dealership north of Denver. No idea why it would be going so long between regens (about 55 hours at that point) but no concerns either.

So, my thought is that I have either somehow ended up with the cleanest burning diesel in the country or something is amiss. I'm just looking for anyone's experiences, thoughts, or whatever. My biggest concern is that something is wrong and that it will manifest itself out somewhere in the middle of a Wyoming oil field 20 miles from the nearest bit of civilization, and 10 miles from any form of cell signal. What do you all think? Can a truck go this long without a regen? What could make a truck run so much cleaner? Is my computer whacked? On that, I really don't think it has regened as I've been paying close attention and have driven enough slow around town roads to have probably caught at least one of the missing regens just by the sound or drive-ability issues one can notice when not cruising the highway. Oh yeah, as for other indicators. My mileage is in line with normal as are my EGTs. The truck runs and pulls just fine. In short, if I didn't have a monitor to tell me something is different I'd not have any indicators to be concerned about.

Thanks for your input,

 

[mweiman]

Are there any signs of soot at the tailpipe? Maybe a cracked dpf that is allowing just enough through to not raise differential pressure?

 

[EDKtrans]

This was a thought I had too, cracked or burned through? I've not seen the insides of one of these dpfs to know what could happen. In answer to your question, no extra soot as of yet and the truck isn't smoking. Perhaps I just ended up with a cheap easy delete?

 

[xcc_rider]

If your dpf was cracked then your tailpipe would be black like mine was. A clean tailpipe means the dpf if fine.
You should go into active regen every 24,000 seconds (common belief is seconds) which means every 6 hours and 40 minutes you should start one so I'm confused unless,
Do you watch the post doc or post nac egt? And if so what does it read when its not in active regen?

To be clear, you're watching the regen status on the CTS and not the evic message system to know when its in active regen right?
Are you watching the dpf pressure also? Just wondering if its doing over the miles.

To be fair, for every "worst" truck made there's a "best" truck made. Maybe you just got lucky...

 

[EDKtrans]

I'm watching the time since last regen, and its always been consistent at around 72,000 seconds or 20 hours. A bit shorter or longer dependent on the load and kind of driving I've been doing and once that I noticed about twice as long on a particularly hard heavily loaded run. My recent driving has not been heavy, hard, or even much of a strain on the truck. I've not heard anything about a set time to regen but I am driving a C/C, not a pickup so perhaps its different.

What were the indicators when your dpf cracked? Did you end up with some codes, limp mode, or just noticing that your pipe was sooty and that regens had stopped? I need to look closer at my tail pipe to see if its gotten any darker. As I mentioned before my major concern is that the truck is going to strand me someplace. If thats likely then I'll replace the dpf.

 

[xcc_rider]

I found this in a post I saved: "Or the ECM has an internal counter that runs anytime the engine is running. This counter is engine RPM and exhaust temperature dependent, so the more RPM the engine is turning or the higher the exhaust temperature, the faster the counter runs. When this counter reaches 24000, or the DPF reaches a soot load of 47 grams, the ECM will try to activate the Regeneration process. This is the Active part of the regeneration process."
I have to assume its seconds as active regen is triggered every 120-250 miles depending on the driving cycle. Even towing I will start one anywhere between 250-350 miles so its pretty close.

I had an event a couple of years ago when my egr valve stuck open and caused the dpf to plug. I lost power and pulled over before I got any codes. Long story short I dropped the trailer and family off at a campground, gave the egr valve a few whacks and unplugged it, cleared the codes and went for a drive at which time it regened and cleared the dpf. The bad thing was I got the P242f dpf over temp code which meant I melted/cracked the substrate but I think it actually helped clear the soot.

Two things FINALLY convinced the dealer that it was cracked, after cleaning the tailpipe several times it would turn black with soot and when I romped on it on a freeway connector and blacked out the sky behind me. I still feel bad for the 18 wheeler that I passed. I know he's still cussing me to this day. So if your tailpipe is clean then the dpf is fine. If not then I really wouldn't worry about it too much.
Interesting thing is there were no codes during this time. Only the soot covered tailpipe to clue me in. Now my tailpipe is perfectly clean.

The C&C does have a slightly different egr and dpf system than our trucks so maybe the timer is set differently. One thing to note, dpfs do have a finite lifetime due to ash accumulation but no one really knows what that can be. If yours is cracked and bypassing soot and ash then yours may last forever. There are stock trucks out there that have over 500k on then with no problems. I'd say yours is working well and i'd just keep an eye on things like you already are.

There is a C&C specific forum on the cumminsforum.com site that you may be able to get more info from.