Regen Every 200 Miles Revisited

[SS Crew]

I stated to read the thread on the Regens Every 200 Miles and by the 3rd page I just didnt' have it in me to read the next 70 pages, but I did some investigation on my own, if this point has been made already I apologize:

I'm doing some remodel work at a Caterpiller equipment dealership and talked to the head mechanic about the frequent regenerations on my truck since the diesel engines on the new equipment has to meet Tier 3 regulations which mean they are running particulate filters. He asked me if I have had my DPF removed and had the ash removed from it by a high pressure air blast, when does my maintenance recommend it? He showed me a contraption that they use to blast the ash from the DPFs, they do that every so many hours. I brought out my diesel supplement manual out and looked and there was nothing in the maintenance schedule regarding DPF cleaning.

He said that since the regens are triggered by a pressure differential, if the truck goes into regen in stop and go traffic or during in-town driving the ash is not removed. The truck probably does a regen cycle for so many miles and if the pressure differential has lower at the end of the specified miles, it stops the regen process. He said that the regen process needs to be done when the engine is under load, such as open highway driving or pulling a trailer (on a highway). The issue causing the frequent regens is probably related to the DPF not being cleaned off after every regen cycle. He said when it goes into regen to drop it down down a gear to keep the RPMs up to blow the ash out and see if that makes a difference as far as extending the miles between regen cycles.

I haven't talked to my dealer yet, but I'm sure they'll dance around the issue and say that the truck is doing the regens as its supposed to.

Any thoughts?

[BanksLB7Duramax]

The DPF is not a "serviceable" item. You cannot remove it and clean it.

Exactly, the regens are triggered by a pressure differential. Therefore the truck will not finish a regen until it sees the proper values. So, ash and soot is being evacuated from the DPF, otherwise the truck would continue the regen, or throw a CEL if the pressure differential didn't change.

[SS Crew]

Originally Posted by BanksLB7Duramax

The DPF is not a "serviceable" item. You cannot remove it and clean it.

I know that the DEF is not a serviceable item, but maybe the engineers overlooked that aspect of the filter - if heavy equipment that uses a DPF at full load most of the time needs to be cleaned in addition to the regen cycles, maybe the DEFs in our trucks would benefit from that being done at every 40,000 to 50,000 miles.

Originally Posted by BanksLB7Duramax

Exactly, the regens are triggered by a pressure differential. Therefore the truck will not finish a regen until it sees the proper values. So, ash and soot is being evacuated from the DPF, otherwise the truck would continue the regen, or throw a CEL if the pressure differential didn't change.

I understand that the computer is supposed to shut off the regen cycle after the pressure differential reading matches what is programmed in the computer, but maybe there is a range that the computer reads after a certain amount of miles - if the reading falls within that range after the mileage cycle (about 40 in my truck), the regen cycle stops. Maybe in time the regen cycles will be more frequent until the computer triggers a CEL. I hope I am wrong, but why is no one is getting the 600 mile regen range that was advertised when the 2011 LML Duramaxes were released? 200 miles is nowhere near the 600 miles that was advertised.

[Sparky21]

It would make sense that there would be some build-up over time. It could be possible that this increases even while allowing the DPF to reach the low DP needed to end the regen cycle. I could also see this changing the surface such that soot would adhere to the DPF differently.
I’m curious to see that dropping a gear and pushing more air through the DPF would do. I suspect it would require more fuel however as there will be more air to heat to the required temperature as well as a lower load on the engine.

[SS Crew]

My truck went into regen mode this morning, I'm going to try dropping a couple of gears on my way home from work to keep the RPMs up to maintain a high airflow to see if this makes any difference on how long until my next regen.

[gave20]

I've gotten 600+ miles between regens. I've also gotten as low as 300 miles between regens. but for the most part I'm around 400-500 miles and only takes about 30 minutes.

[SS Crew]

Originally Posted by gave20

I've gotten 600+ miles between regens. I've also gotten as low as 300 miles between regens. but for the most part I'm around 400-500 miles and only takes about 30 minutes.

Do you do a lot of highway driving?

[gave20]

No I average about 41 or so and my daily commute is aroun 15 miles or so one way. Those high regens were nearly all highway though and the short regens were doing the hottest part of the summer. On mine outside temp was the biggest factor in regen cycle, as soon as it got hot 70 at night 90 during the day the regens shortened up. As soon as it cooled off it went right back to normal.


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[PrivatePilot]

Originally Posted by BanksLB7Duramax

The DPF is not a "serviceable" item. You cannot remove it and clean it.

They are on class 8 equipment, which I think is where he was coming from.

Read about it here: http://www.hdrg.org/2011Presentations/SPX.pdf

[dmax3500]

could the 11'-13' trucks do less regens because of the ''DEF'' fluid acting like a high-pressure steam cleaner and helping to get rid of the ash/soot?