Understanding Regeneration

[GShelton]

You're right, as usual, that someone needs to 'splain it better. Until then I guess I'll have to attribute it to magic.

George

 

[TJJEEPER]

Some thoughts about the fuel itself.
ULSD fuel has a flash point of 100-150 degrees (awful wide spread?) and a self igniting point of 450 degrees *. If there is any oxygen available it is going to burn, exhaust valve open or not.

What got me to thinking about this was the fact that if you are introducing a mist into the exhaust stream it should reduce it's temp. The fact that you are seeing 1200+ degrees might indicate there is enough O2 to ignite that charge and we're dealing with semantics on if it's introduced to burn or not (as Wolfy mentioned earlier, not part of the power stroke). It's probably not burning the entire charge so you have enough to light the catlyst?

*MSDS

Gawd I love this place... Thanks for the work Wolfy!

 

[ModifiedDiesel]

Just picked up my truck It does not seem as the TSB for REGEN was performed however they did apparently reprogram the ECM with 18190434.



Does anyone know what this number stands for?



Oh also, the Claim Number is 027815 if that helps anyone.



Thanks in advance.

 

[Wolfy]

Just picked up my truck It does not seem as the TSB for REGEN was performed however they did apparently reprogram the ECM with 18190434.



Does anyone know what this number stands for?



Oh also, the Claim Number is 027815 if that helps anyone.



Thanks in advance.

Congratulations on the new rig!



Don't know about the numbers you mention,... but if your truck is a 2500/3500, 6. 7L and was built AFTER june 11th (i. e. , on-or-after June 12), it should already have the corrected "regen" flash covered in TSB 18-033-07 REV. A.



SHOULD have!



If built on or before June 11, it probably needs it, if the dealer has not done it already.

 

[ModifiedDiesel]

I'll have to take in the TSB number and talk to them, unfortunately I picked up the truck after the service department was closed. They did get my high idle enabled which is pretty cool tho.

 

[MCummings]

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Following the nifty drawing I made...



Exhaust exiting the manifold and going into the turbo are the hottest, but then the turbo absorbs some heat, cooling the gas off, then goes onto the nOX filter, cooling off more, by the time it comes around to the DOC, it's pretty cool, but a chemical reaction heats the gas enough to allow the DPF to burn off any soot that has accumilated.



I believe that as soon as teh exhaust begins to exit the cylinder, it begins to cool off. The reason the EGT is higher. is because of the extra fuel that was injected after the powerstroke, not allowing the gases to cool as much as normally would occur happen.



I *feel* that the highest temperature we see is in the manifold, and only cools as the gasses travel downstream...



Merrick

 

[CUMMINZ]

M

Something is wrong here. Look at all the black smoke!!



CUMMINZ

 

[Wolfy]

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Following the nifty drawing I made...



Exhaust exiting the manifold and going into the turbo are the hottest, but then the turbo absorbs some heat, cooling the gas off, then goes onto the nOX filter, cooling off more, by the time it comes around to the DOC, it's pretty cool, but a chemical reaction heats the gas enough to allow the DPF to burn off any soot that has accumilated.



I believe that as soon as teh exhaust begins to exit the cylinder, it begins to cool off. The reason the EGT is higher. is because of the extra fuel that was injected after the powerstroke, not allowing the gases to cool as much as normally would occur happen.



I *feel* that the highest temperature we see is in the manifold, and only cools as the gasses travel downstream...



Merrick

Nice drawing, Merrick!



Thanks for the time/effort, ... I know there is more work in those things than most might expect.



As for the (gauge) EGT being higher "because of the extra fuel", ... this is plausible only if the fuel "burns", contrary to Cummins emphatic statements,... a hitch in our reasoning get-along that just won't go away.



It would certainly be convenient, for making sense of all this, to ignore their statement, ... but doing-so would involve a bit of "sweeping under the rug".



If the fuel does not burn, then injection of the (cooler) fuel into the heated gases should have a cooling effect, not a heating one, on the mix,... and thus show cooler on-the-gauge.



Back to the drawing -



Maybe you can add the sensors, and we can use your work as a discussion base for the whole system(?).



My info is as follows:

[Bracketed alpha-numerics refer to my schematic as described in last paragraph of this post]



3 oxygen sensors ( 1 in "NOX filter"[1]) (1 pre-DOC[2B]) (1 Post-DOC[2A])

3 exhaust-temp sensors ( 1 pre-DOC[3C]) ( 1 post-DOC/pre-DPF[3B]) (1 post DPF[3A])

2 pressure sensors ( 1 pre DPF "inlet"[4B]) (1 post-DPF "outlet"[4A])

I pressure-differential sensor [5](fed from both pressure sensors via hard-tubing and hose,... all other sensors have "wiring" connections. )



[FWIW, there is some Cummins literature which labels the item you have named "NOX filter",... as "DOC #1", ... with the DOC you show being labeled by Cummins as "DOC #2". I don't know why they do this. Anybody understand this?]



I had made a schematic of this set-up, but didn't know how to post it here. I will attempt to do so,... have no idea if/where-in-post it will appear. (I tried, unsuccessfully, to make it larger than it shows in the preview) The corresponding numbers as labeled on my sketch are included in brackets AFTER each bit of sensor info given above. My "truck" is backwards, with regard to yours,... and quite boxy. I like yours better!

 

[MCummings]

Ok, Here is a pic for CUMMNZ while I add the sensors. .



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Merrick

 

[CUMMINZ]

Now MC that is the type of humor we need. Great thinking , you made my day. :-laf



CUMMINZ

 

[MCummings]

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Feel free to comment on anything else yall think this pic needs.

Thanks CUMMINZ



Merrick

 

[CUMMINZ]

MC



Since you like in Laredo, that means you see all the rail car/truck carriers coming out of Mexico??



CUMMINZ

 

[MCummings]

I sure do, but I cannot legally get to them.



There is a huge holding yard at the outskirts of town. Hundreds upon hundreds of brand new vehicles waiting to continue into the states.



Merrick

 

[CUMMINZ]

When I ordered my 04. 5 I traced it from Mexico thru Laredo toward New Orleans to Winston-Salem, NC where I know the manager of the unloading facility. When they got it off the rr car they parked it at the office on a Sunday morning and my wife and I drove there to drive it home.



CUMMINZ

 

[Bob4x4]

Just picked up my truck It does not seem as the TSB for REGEN was performed however they did apparently reprogram the ECM with 18190434.



Does anyone know what this number stands for?



Oh also, the Claim Number is 027815 if that helps anyone.



Thanks in advance.

The # 18 19 04 35 is the labor operation # for performing the latest flash that everyone is discussing here.

 

[RColston]

UGH... the more I read... the more convinced I am that I need to keep my 01. 5.

 

[MCummings]

Check out the post turbo EGT's from this 6. 7.



https://www.turbodieselregister.com...smissions-2007-5/186524-new-truck-report.html



Under 1,000*F.



Merrick

 

[qzilla]

Merrick,

There is only a Cat (DOC) and a DPF on the truck. There is no NoX filter on the truck at all.

The temps are not an issue and the temps at all points in the exhaust are lower than peak temps at the manifold. Yes, I have data, real data and no i am not posting it.

If you really want to know, go buy a $50 scan tool at Autozone and it will show the OBD2 version of 2 of the temps before and after the DOC. They are not that hot. The hottest one is the middle one or the one after the DOC. The DOC does heat the exhaust some but, not like what you think.

Starting in 04. 5 the valves and other heat sensitive parts have an incolonel coating to allow heat protection in the 1400-1450 range. That is for sustained periods. You can peak the temps higher than that without severe damage. The 6. 7's are actually better than the 600 series motor with heat, or so they were designed that way.

Now, let me give you a brain stumper. The EGT's are considerably hotter without the DOC and DPF than with them... ... . go figure that out. No peak but, cruising, non regenerating temps are hotter.

Other than that i cannot say too much other than it won't be long and this sort of discussion will be a mute point.

You can clog them if you are not careful. They hurt performance on average to the tune of 13-17rwhp as well. When you remove them the trucks smoke considerably more in stock trim as well, so they are working the filter pretty hard in stock trim.

At this time if you want to make hardly any more power over a period of time they will need to get lost from the truck, or fall off or something.

 

[CUMMINZ]

Hey Q What is this thing?

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[courierdog]

Regen

The DPF is a two part device in the Pick-Up as opposed to the one piece unit in the Chassis Cab. So what action is happening in which device. Second, there are occasions when my truck does spit out huge amounts of very black smoke, in fact, once when the driver on the hwy was not under any circumstance allow me to merge I floored the pedle t the metal and I heard a loud band followed by a huge kick in the pants leaving said unco-operative person in a very black cloud. This was followed by a strange event on the overhead console milage indicator indicating an initial dip followed by a sharp increase in the milage back to the previous norm, before the last reflash. Since that point my milage has returned to the pre flash milage, this is a good thing as since the reflash my milage has been poor due to the agressive regen cycles. Could this be the soot has been blown out and now has been returned to normal? BTW d not put your hand or any unprotected part near the exhaust, it singed all the hair off when I held it 6 inches away from the tail pipe, that is hot! The back bumper is all black on the Exhaust side and takes a good deal of scrubbing in the car wash to remove the accumulated soot.

Other wise the truck is running very well. I now have 22,000 Km or 13,400 miles on the clock. and no truning the key to on 3 times (with in one minute) does not provide any codes on the display!