Diesel Regeneration

[akadeadeye]

There has been some discussion of this on other threads.

I have a question. In over one year of motorhome ownership and 12,000 miles, I have not known if a regeneration has occurred or not. Is it possible that it occurred while driving and I didn't know about it. I have not done a manual regeneration.

Don

[powerboatr]

my freightliner book and the cummins book says the engine under MOST conditions generates enough exhaust heat to keep the DPF clean while driving at highway speeds under load and may not ever have to go into regen...

i have no manual switch and have never had a regen light come on either.
someone told me we have a manual switch buried in the wiring harness under the dash...but i never found it

[bdpreece]

I have had my 08 400 ISL since June of this year and have had it go into regen twice,. Once when I picked it up from Cummins after having work done and once after having set inline for a long time at Flying J waiting to get fuel. From what I understand there is a way to do a manual regen but so far all I have had to do do was drive on the freeway for about 20 minutes.

[Iron Man]

Regen depends on your driving conditions. You should have a yellow indicator on you instrument panel that lights up when it is a regen mode. Consult your engine's owner manual in the black box of manuals in your coach.

[enjoyrv]

Ok, someone has to tell me what regen means.

[Eric_H_E]

Quote:

Originally Posted by enjoyrv Ok, someone has to tell me what regen means.

same here

[RustyJC]

Quote:

Originally Posted by enjoyrv Ok, someone has to tell me what regen means.

The regeneration (regen) cycle is designed to clean the DPF (diesel particulate filter, which is basically a black soot trap) and, if so equipped, the NOx adsorber. Regeneration requires extremely high exhaust temperatures to "burn" (oxidize) the carbon trapped and held in the DPF and to purge the NOx adsorber. This high EGT can be accomplished on HPCR, electronically injected diesels with an additional injection event timed very late on the engine's power stroke or cycle or with an additional injection nozzle that injects fuel in the engine's exhaust ahead of the DPF and NOx adsorber. Part of the regeneration process also includes purging the NOx adsorber to remove the sulfur compounds that are also trapped there due to the residual sulfur present even in ULSD diesel (15 ppm limit).

Rusty

[clnhse]

The main thing with these motors is to not let them idle......Try to stay above 45mph and run them loaded. The more the motor works the hotter it will run and the less chance it will need to do a forced regen.....If that little motor is doing all it can it will do a passive regen...

[akadeadeye]

Quote:

Originally Posted by RustyJC The regeneration (regen) cycle is designed to clean the DPF (diesel particulate filter, which is basically a black soot trap) and, if so equipped, the NOx adsorber. Regeneration requires extremely high exhaust temperatures to "burn" (oxidize) the carbon trapped and held in the DPF and to purge the NOx adsorber. This high EGT can be accomplished on HPCR, electronically injected diesels with an additional injection event timed very late on the engine's power stroke or cycle or with an additional injection nozzle that injects fuel in the engine's exhaust ahead of the DPF and NOx adsorber. Part of the regeneration process also includes purging the NOx adsorber to remove the sulfur compounds that are also trapped there due to the residual sulfur present even in ULSD diesel (15 ppm limit). Rusty

Yeah, what Rusty said!

Don

[enjoyrv]

Thanks Rusty. I would have never figured that one out. Good to have someone with knowledge on the subject on the forum.

[Mopar1973Man]

Here is Cummins Stand point...

OPERATION

The oxidation catalyst raises the exhaust gas temperatures to regenerate the DPF, which is passive regeneration. If the passive regeneration cannot keep up with the build up of soot in the DPF, the ECM will actively regenerate the DPF to burn off the soot. Residue remains inside the DPF in the form of non burnable ash. Ash comes from the oils and other materials that are trapped in the oils and are present in the soot. The catalyst contains a large number of parallel channels, which run in the axial direction and are separated by thin porous walls. The channels are alternatively open at one end, but plugged at the other. The exhaust gases flow through the walls and escape through the pores in the wall material. Particulates, however, are too large to escape and are trapped in the monolith walls. The ECM starts the regeneration of the DPF if the soot load exceeds a performance map value. The ECM determines the load condition of the DPF based upon the exhaust gas pressure upstream and downstream of the DPC/DPF. A pressure differential sensor provides the pressure input to the ECM. During the regeneration process, the ECM raises the temperature in the DOC/DPF to burn off the soot accumulated. Under normal operation, the engine does not produce enough heat to oxidize the soot inside the DOC/DPF. This process requires temperatures above 550 °C (1,022 °F). After regeneration, the ECM reads the actual pressure difference at the DOC/DPF and compares it with a reference value. From this comparison, the ECM determines the ash quantity inside the DOC/DPF.

As for flash points of different fuels... (Carbon)
Fuels and Chemicals - Auto Ignition Temperatures

[powerboatr]

Quote:

Originally Posted by Mopar1973Man Here is Cummins Stand point... OPERATION The oxidation catalyst raises the exhaust gas temperatures to regenerate the DPF, which is passive regeneration. If the passive regeneration cannot keep up with the build up of soot in the DPF, the ECM will actively regenerate the DPF to burn off the soot. Residue remains inside the DPF in the form of non burnable ash. Ash comes from the oils and other materials that are trapped in the oils and are present in the soot. The catalyst contains a large number of parallel channels, which run in the axial direction and are separated by thin porous walls. The channels are alternatively open at one end, but plugged at the other. The exhaust gases flow through the walls and escape through the pores in the wall material. Particulates, however, are too large to escape and are trapped in the monolith walls. The ECM starts the regeneration of the DPF if the soot load exceeds a performance map value. The ECM determines the load condition of the DPF based upon the exhaust gas pressure upstream and downstream of the DPC/DPF. A pressure differential sensor provides the pressure input to the ECM. During the regeneration process, the ECM raises the temperature in the DOC/DPF to burn off the soot accumulated. Under normal operation, the engine does not produce enough heat to oxidize the soot inside the DOC/DPF. This process requires temperatures above 550 °C (1,022 °F). After regeneration, the ECM reads the actual pressure difference at the DOC/DPF and compares it with a reference value. From this comparison, the ECM determines the ash quantity inside the DOC/DPF. As for flash points of different fuels... (Carbon) Fuels and Chemicals - Auto Ignition Temperatures

you get the GOLD star for today.

[akadeadeye]

If the ECM forces a regen, will there be a message indicating when this is happening?

Don

[Mopar1973Man]

Quote:

Originally Posted by akadeadeye If the ECM forces a regen, will there be a message indicating when this is happening? Don

Usually a REGEN light will be present in the instrument cluster...

Now how this is performed is wild basically the engine run as usual but on the exhaust stroke the ECM commands for multiple injections of fuel to be sprayed in the exhaust stroke to flood the exhaust stream with fuel and fire in hopes of burning the DPF clean. As you seen from my doc from Cummins it needs to be over 1000*F EGT's to burn that DPF clean...

People wonder why the older diesels performed better in the MPG game...

Something to see...

http://www.youtube.com/watch?v=4Yz97pYUlBM