Understanding Regeneration

[Wolfy]

To All,



The attempted explanation below is the result of study of materials from Dodge/Cummins, collected from several sources, including links posted here by TDR members. Apologies in advance for any typos or inaccurate info. It is my best effort, but there is much I have yet to learn. No apology for the length. Not everything will fit in a nutshell.



For a reasonable period of time, I will monitor this thread, and will try to add substance, "edit" notes, or pointers to additional discussion where appropriate.



[Corrections/additions are welcome ]



Several questions have been raised in thread discussions, and I believe some of the answers are to be found in what follows.



IMPORTANT: Remember that the figures quoted are approximate,... "ball park" figures arrived-at by combining slightly-different figures given by different sources. We are after a basic understanding of the process,... not attempting to exactly describe conditions for any given situation.



Also note the distinction between "gauge" readings,... and DOC/DPF temperatures.



Capitalization used for emphasis,... not volume.



To begin with some "facts":



1. "Regeneration" is the process of ridding the DPF (Diesel Particulate Filter) of soot which has accumulated from the passage of carbon-laden exhaust gases.



Under "IDEAL" circumstances, which will be described, the first portion of the DPF, which is the DOC(Diesel Oxidative Catalyst), will chemically "reduce" various compounds in the products of combustion,... and these changed elements will then recombine in such ways that carbon(black "particulate matter", or "soot",) will be changed into CO2 gas(colorless) and exit the exhaust as a relative non-pollutant. [ Nitric oxide (NOX), a compound in the exhaust gas,is oxidized or "converted" by the DOC into nitrogen dioxide (NO2), which then combines with entrained or trapped(in the DPF) soot(carbon) to make CO2,... Voila! No smoke!]



When conditions are NOT IDEAL, the process will be incomplete, and additional carbon will remain in the solid state, and be trapped and held in the DPF.



This trapped carbon, if allowed to accumulate, will eventually "clog" the filter/exhaust-flow, and impair engine operation.



This carbon accumulation is what calls for "regeneration" as defined above.



The process involves restoring more ideal conditions, so that accumulation may be stopped, and previously-accumulated carbon may be "converted" and exit as CO2.



2. Defining "ideal" conditions:



Regeneration requires DOC/DPF temperatures ". . above 1022 deg. F. " (per Dodge/Cummins training materials). (Or, from other Cummins info ... " requires temperatures above 1112 deg. F. ") [The figure "1100 deg. " will be used in discussion here, as a good approximation. ]



Also required is a properly manufactured/functioning DOC. (This requirement will be assumed to have been met in what follows. )



3. The normal-operation exhaust gases from the engine MAY NOT PROVIDE sufficiently high temperature at the DPF, for the regeneration process, if the pre-turbo gauge reading is less-than approximately 872 deg. F. [See "Sidebar" about MINIMUM CONDITIONS below]!



(Pre-turbo installation of an ISSPRO EGT sensor ("pyro") gives normal highway speed temps on the gauge in the neighborhood of 800-1000 deg. This is REDUCED by some amount up to 500 deg. by the time the gases pass through the turbo, and reach the DOC/DPF ( ... according to Banks, to quote only one "authority").

[I will use a commonly accepted average loss of 300 deg. in this discussion. ]



Let's say we are cruising at 75 mph, on a day with a certain ambient temperature, with a certain load, so that our gauge-reading is 1000 deg.



So,... we have a need for 1100 deg. in the DPF, BUT an engine-provided temp of only about 700 deg at-the-DOC(using as our example 1000(gauge) minus 300 turbo-loss). This 700 degrees is still comfortably above the 572 deg. Cummins-described minimum.



[ "Sidebar" Re. "MINIMUM CONDITIONS":

Cummins states that "Passive regeneration takes place when exhaust temperatures exceed approximately 572 deg. F. ". Nothing is said about where these gases are to be measured,... I am assuming this statement means exhaust gases entering the DOC,... so this minimum satisfactory condition would be reached with a gauge reading of 872 deg. , when the 300 deg. turbo-loss is factored-in.

If the 572 deg. exhaust gases are just adequate (as per Cummins' statement), and this in turn insures the also just adequate DOC-boosted temp of 1100 deg. , we would have these overall MINIMUM system conditions for regeneration:



Exhaust gases at EGT sensor(gauge reading) - 872 deg. , post-turbo exhaust gases entering DOC - 572 deg. , ... "DOC-boosted" gases entering DPF - 1100 deg (... indicating a 528 deg "boost" from catalytic action,... a near doubling of the gas temperature!)



4. Returning to discussion of our more normal (than the absolute minimum) set of conditions, we had a gauge reading of 1000 deg. , and turbo-loss of 300, so were left with 700 deg. at the DOC. The additional heat (+400 deg. or more) which raises the temperature to-or-above the 1100 deg. required for the process, comes from the effect of the DOC!



As in many chemical reactions, the "reduction" of exhaust gas compounds, and the "catalyzed" oxidation of some elements, results in heat production. This heat energy, when added to that already present in the exhaust gas from the engine, raises the temperature to the level where the regeneration process can be accomplished.



To better understand this, remember that a fire is essentially the "oxidation" of wood(for example). Plenty of heat generated by that familiar chemical reaction, no?



At sufficient temperatures, one of the "reduced" compounds, nitrous dioxide, while then flowing through the filter, recombines with the entrained or previously-accumulated solid carbon ("soot"), and transforms it into a gaseous state, as carbon dioxide (CO2). [Another product of the whole filtering process is "ash", which accumulates in the filter in much smaller amounts, and must be physically removed, by a "cleaning" process at the service department, supposedly some hundreds of thousands of miles down-the-road. We will not discuss that process here. ]



5. The process we are discussing, as described to this point, is called "PASSIVE REGENERATION", it is on-going, given conditions as described, and no indication of its occurrence is given, via EGT, EVIC(Electronic Vehicle Information Center) or otherwise. The operator is unaware.



[Continued in Pt. II]

 

[Wolfy]

Understanding Regeneration (Part II of II)

[Continued from Part I ]



6. We have assumed, in the foregoing discussion, a "normal" operating engine-temperature of 800-1000 degrees, which suited our needs for regeneration, when given the temp-boost from the DOC. This "normal" condition is typically represented by highway-cruise useage (Cummins refers to 50-60 mph, in this context). It is not the speed, however, but the temperature, which is important to the regen process, An EGT sensor/gauge is a definite, plus,... and is the most highly-recommended gauge where such things are discussed.



Operating practices other than " normal", i. e. , low-speed, or repeated short-term use, such as errands, delivery stops, etc. ,(... termed "light duty-cycle") DO NOT PROVIDE SUFFICIENT STARTING-POINT TEMPERATURES for the DOC to work with, when "boosting", and so the final temp presented to the DPF, even after DOC action, is NOT SUFFICIENT for regeneration to occur!



[Remember the "MINIMUM CONDITIONS" discussed above. ]



Presumably "light duty-cycle" operation is operation which does not give the minimum (approximately 872 deg. at gauge) temperature, or does not reach that temperature for long-enough periods, for regeneration to be accomplished.



THIS SITUATION RESULTS IN SOOT ACCUMULATION IN THE DPF. This accumulation is detected by inflow-pressure vs. outflow-pressure sensors on the DPF, and the ECM (Engine Control Module), at a certain impeded-flow level, initiates "ACTIVE REGENERATION". [Before this condition is reached, the EVIC will/may/should inform and prompt the operator to drive for a sufficient time at sufficient speed to elevate temperatures so that passive regeneration will restore optimum or at least reduced soot-levels in the DPF. This "percent full" warning is the first indication to the driver that anything needs attention. ]



7. Active regeneration involves the injection of additional fuel, into the exhaust stream, before the DOC, and it is the chemical action of the catalyst in oxidizing this additional fuel which INCREASES THE TEMP BOOST to the level previously described as necessary for regeneration to occur. [The additional injection has put "more wood on the fire", so to speak ]



Some Cummins literature, which discusses this process, has illustrations which show a separate injector, called the "dosing injector", in the exhaust line up-stream of the DOC/DPF whereby the additional fuel for active regeneration is introduced.



The 6. 7L in our trucks has NO such additional injector, but uses a separate injection event from the regular injectors, during the exhaust stroke, to accomplish the same thing. {Edit:See posts # 13 from Wolfy, and #14 from THanley in this thread for further discussion of these design variations. }



This "active regeneration" process is not operator controlled. It is an "automatic" function of the ECM, as prompted by a pressure-differential sensor which monitors the pre/post-flow sensors on the DPF. If it is unsuccessful, and the filter becomes too clogged for acceptable function, the ECM will limit the engine to "limp" mode, and advise the operator to seek service.



So much for facts.



Now for some suppositions based upon them:



The instructions being given to owners, to "take it out and drive at highway speeds for 45 minutes" or some such,... are intended to insure that the system has proper conditions for "passive regeneration" to occur, whereas perhaps the driver's ordinary habits did not provide such conditions( i. e. , the truck was being operated "light duty-cycle").



Additionally, this insures that, if the ECM detects soot accumulation to the point where flow is impeded, and "active regeneration" is required, engine exhaust temperatures will be high-enough to begin with, so that the added-post-combustion injection of fuel, combined with the action of the catalyst, will GIVE THE WHOLE SYSTEM THE BEST SHOT AT ACCOMPLISHING THE GOAL OF REGENERATION.



If this best-effort is not effective,... something is wrong,... period.



The trouble may NOT be with the mechanical-chemical system, however,... but with the ECM. A badly programmed ECM, or one which is faulty, may indicate non-existent problems, or initiate "active regeneration" unnecessarily or too-frequently.



I believe THIS IS A BAD THING!



Here's why:



If an un-needed injection of additional fuel is added to a system with already-adequate temperatures, the temperature will be raised, just as it is expected to be,... but NOT WHEN IT IS SUPPOSED TO BE! Raising a temperature which is "high enough",... gives us a temperature which is TOO HIGH! (We have already discussed the DOC's capability for increasing temps rather dramatically!)



Think about this - Owners have reported an "active regen" frequency of, let's say, once an hour, with temperatures from a pre-turbo sensor of up to 1400-1500 deg.



First, this would indicate an alarming rate of soot-accumulation, which is hardly to be expected (the reports related to "highway driving"). Fuel economy figures would be adversly effected by constant post-combustion injection/loss of fuel which does nothing to propel the truck.



But more significantly, think about what the gauge-temp reading indicates.



The turbine is DOWNSTREAM from the EGT sensor(exhaust stream-wise), ... therefore the actual temp AT THE TURBINE (which is closer to the DOC - the source of the increased heat levels, when acting upon the additional injected fuel) MUST BE HIGHER!



Higher than the gauge-indicated 1400-1500 deg!



This is (according, again, to Banks) definitely a POTENTIAL DAMAGE-TO-THE-TURBINE situation. [ Note - The color-indications for temp ranges on the ISSPRO gauge are as follows,... green(normal) to 1050,... yellow (high, caution) to 1250, red(too-high,danger) to a max reading of 1500 deg. ]



Banks states that the damage may be cumulative,... and will not necessarily be immediately evident from a single or several repeated events.



Bottom line: OPERATION AT THESE TEMPERATURES IS NOT A GOOD THING!.

{Edit:Additional mention of this concern can be found in post #13 of this thread}



If your rig is behaving in this manner, I suggest getting it to a dealer ASAP, and having the current re-flash ["TSB #18-033-07 REV. A" (dated June 12, 2007,) for 2500 and 3500 pick-ups, as this is written]done, and done CORRECTLY!



FWIW, by sheer good-luck delivery date, my truck was picked-up with the "REV. A" flash accomplished by the dealer (Dishman), and although I have only driven it 754 miles(mostly highway / varying speeds) at this writing, operation has been completely normal, with no EVIC notices of any kind. I assume passive regeneration is taking place as designed.



A final note:

The literature I have seen makes brief reference to "stationary regeneration" being possible/appropriate when "light duty-cycle" operation makes it necessary.



Sadly, though, absolutely nothing was said about the procedure,... i. e. , how it is to be accomplished, ... nor was there any suggestion as to where to seek further info on it. {edit: See post #4 - this thread}



Wrap-up: although I have spent considerable time researching/thinking/writing this message, I am not an authority, and hopefully others will add/correct, etc. , as we attempt to learn more about these trucks.



Hope this presentation is helpful to someone!



Good luck with your rigs!

 

[Steve St.Laurent]

I combined these two threads together so the information doesn't get separated on the thread list.

 

[Bob4x4]

[Continued from Part I ]

.

A final note:

The literature I have seen makes brief reference to "stationary regeneration" being possible/appropriate when "light duty-cycle" operation makes it necessary.



Sadly, though, absolutely nothing was said about the procedure,... i. e. , how it is to be accomplished, ... nor was there any suggestion as to where to seek further info on it.

about these rigs.



Hope this presentation is helpful to someone!



Good luck with your rigs!

I was told this was eliminated before the production vehicles ever hit the dealer floors,it created unsafe temps while there was no airflow,keeping the carpets from melt down and anything under the truck to ignite.





Bob

 

[ModifiedDiesel]

7. Active regeneration involves the injection of additional fuel, into the exhaust stream, before the DOC, and it is the chemical action of the catalyst in oxidizing this additional fuel which INCREASES THE TEMP BOOST to the level previously described as necessary for regeneration to occur. [The injector has put "more wood on the fire", so to speak ]
This "active regeneration" process is not operator controlled. It is an "automatic" function of the ECM, as prompted by a pressure-differential sensor which monitors the pre/post-flow sensors on the DPF. If it is unsuccessful, and the filter becomes too clogged for acceptable function, the ECM will limit the engine to "limp" mode, and advise the operator to seek service.

Correct me if I am wrong, but I do not believe the 6. 7L's DPF has an extra fuel injector in its exhaust stream so "Active Regeneration" is kind of hard to accomplish. I'm guessing DC "value engineered" this Cummins DPF feature out of our trucks.

 

[Steve St.Laurent]

You could easily send fuel to the DPF by opening the injector while the exhaust valve is open.

 

[ModifiedDiesel]

I guess that is true, but typically in the Cummins OTR truck systems I have seen advertised there is an additional injector in the exhaust right before the DPF.

 

[Wolfy]

Correct me if I am wrong, but I do not believe the 6. 7L's DPF has an extra fuel injector in its exhaust stream so "Active Regeneration" is kind of hard to accomplish.

I was puzzled by this as well.



Underneath the truck yesterday, I was unable to find any "fuel" looking lines to the DPF assembly anywhere below(after) the turbo. The only hard tube/hose lines( as opposed to electrical wires) were two that I believe go from the fore/aft pressure sensors on the DPF to the pressure-differential sensor which "advises" the ECM.



I wonder, though, about some connections on top of the turbo between the two rotor housings. I am new to turbos, so don't know what I am looking at. But there are some possible-candidate looking fittings there,... and it seems that injection into a spinning exhaust rotor might be a way to maintain droplet-dispersion(atomization), for better surface-area exposure for catalyzation. (Can't see into that area really well. Wild-guessing here.



Surely some knowledgable TDR members can tell what is/isn't there.

 

[TConnolly]

My dealers service manager told me that adding fuel is a misconception, and that it in fact (his words not mine) would cool the the system in a diesel. He said that to increase the exhaust temperature the engine is leaned.



Anyone have an opinion on that?

 

[Wolfy]

My dealers service manager told me that adding fuel is a misconception, and that it in fact (his words not mine) would cool the the system in a diesel. He said that to increase the exhaust temperature the engine is leaned.



Anyone have an opinion on that?

"Banks Power" does.



Here's a quote: "The richer the air/fuel ratio in a diesel, the higher the EGT will be. "



And here's a link to EGT discussion:



http://bankspower.com/Tech_whyegt.cfm

 

[Bob4x4]

My dealers service manager told me that adding fuel is a misconception, and that it in fact (his words not mine) would cool the the system in a diesel. He said that to increase the exhaust temperature the engine is leaned.



Anyone have an opinion on that?

That is BS... ... ... it is true on gassers :-laf not diesels.

Tell your svc manager to go back to school before he misleads anyone else.



Bob

 

[Jim Potteiger]

I drove my truck back to the dealer this morning and had the flash completed. It took approx. 30 minutes to complete. My truck showed showed no codes. I drove the truck from the dealer and within 8 miles my pyro gauge went to 1200 degrees. After 13 minutes or 9 miles the temp. dropped to 900 degrees indicating the regen was completed. I will drive the truck approx. 300 miles tomorrow and see what happens.

 

[Wolfy]

Regarding the apparent lack of any visible "downstream" injector for the active regeneration:



QUOTE=Wolfy;1779558]I was puzzled by this as well.

Underneath the truck yesterday, I was unable to find any "fuel" looking lines to the DPF assembly anywhere below(after) the turbo.

...

Surely some knowledgable TDR members can tell what is/isn't there.

Spoke today [6/21/07] with Josh at Dishman Dodge, who has been looking into what info he and his service department have on this question. He was reading to me from a manual that was 6. 7L specific, so the info should apply.



There WAS distinct mention of a "post" injection, which operated only during active regen,... but nowhere was there any diagram showing any additional injector, or any mention of one. (I take "post" to mean after the normal combustion/power stroke. )



I have previously read written material from a forgotten source which made a point of the fact that this system is capable of multiple injection "events".



Our combined best-guess, at this time, is that the regular injector(s) is(are) utilized, in a separate injection "event", timed so as to place raw fuel into the gases being ejected on the exhaust-stroke, through the open exhaust valve, and thence downstream to be acted upon by the catalyst where the temperature is raised by a catalytized chemical reaction. Cummins is emphatic and specific in stating that the fuel is "NOT BURNED",... which I assume is because sufficient oxygen needed for combustion is absent in the already-combusted exhaust mix.



If "burned" means oxidized, though, as it conventionally does (burning is rapid oxidation, rust is slow oxidation), then the term "diesel OXIDATION catalyst" suggests that oxygen is supplied by the reduction of compounds in the exhaust gases, which releases oxygen to combine with the fuel(oxidize/burn), creating heat in the process, as does all rapid oxidation. It is this additional heat, generated in the DOC, adding to the heat already present in the mix, which raises the temperature in the DPF to an effective "regeneration" level of 1100 deg. +.



We will pursue this how/where/when of this "post" injection further, as info becomes available.



Comment welcome! Gotta be some chemists/engineers out there [/QUOTE]



--------------------------------------------------------------------------



FOLLOW-UP:



After looking into the matter further, Josh got back to me today [6/22/07]with verification of our "best guess" of yesterday (see above quote).





Here is his comment;



"There is no post combustion injector in the 6. 7L... there IS what is called post combustion injectION, however. Basically, the injectors can fire four different ways... 1 being pre-combustion, 1 during normal combusion, the other 2 are reserved for 'POST COMBUSTION INJECTION. " this fires the injector when the exhaust valve is open, making the fuel/air mixture VERY rich, going into active regeneration. "



This verifying information establishes that we need not look for any "additional" injector anywhere in the exhaust system, ... and tells us how/where the "additional fuel" for the active regeneration is added.



What we still do not know, and are unlikely to find out, I think, is this: If the fuel added in this fashion raises a previously-indequate-for-regeneration exhaust gas temperature at the DPF to an "adequate " level, after passing through/being acted upon by the DOC, ... what would be the effect of such "post injection", if it was a result of a misguided ECM adding it to an ALREADY-ADEQUATE temperature?



Surely it would raise it still higher, to probably undesireable and potentially damaging levels (as discussed in previous post)!



And (also previously mentioned) since the EGT sensor is upstream from the heat--raising action of the DOC, "excessive" temperature readings of 1400-1500 degrees ON THE GAUGE, can only mean even higher temperature at the turbine, which is "closer to the action"!



A stated before, what we have learned suggests strongly that a faulty ECM should not be permitted to run-amok, initiating un-needed active regeneration willy-nilly.



GET the appropriate re-flashes as they become available!



[ I will add this new info to the main "understanding regeneration" thread shortly]



Comments always welcome!

 

[THanley]

As was mentioned previously, the Cummins 11 and 15 liter engines in the big rigs have a separate fuel injector in the exhaust system (post turbo) for active regeneration. That is because these engines do not have HPCR fuel system at this time. The 6. 7 liter engine with HPCR achieves active regeneration by injecting fuel into the cylinder after normal combustion has ceased (exhaust valve open). This extra fuel is what lights off the aftertreatment in an active regeneration scenario on the 6. 7 liter engine.

 

[CogginsP]

I like this thread a lot, it's answering a lot of questions and misconceptions I had of the new 6. 7. Thank God people here at the TDR are willing to do the research on this...



I also kind of find it depressing that our members DO have to do the research and DO have to ask the questions. This new diesel technology is so confusing... it kind of makes me wish we could just get one of the chief Cummins engineers in here and say "THIS is what the system is and THIS is how it works!"

 

[Wolfy]

I am wondering if while towing and your system is taxed with the tow and your temp reaches the high levels very often if the system would even call for a regen?

Cumminz,



It is my understanding that this is what would happen; The system is AUTOMATICALLY REGENERATING any time a certain temperature is reached in the system. This is called "passive regeneration", and is on-going anytime conditions are right (meaning temperatures in the exhaust system are high-enough AT THE DOC/DPF).



The only reason (so far as we now understand things) "Active regen" will be initiated is if/when DPF pressure differential sensor detects a soot build-up (partial blockage) in the DPF. (This build-up will occur if conditions are not right for passive regen OFTEN ENOUGH to keep the soot in the filter, burned-off(due to driving time being too-short, or engine speed being too low/loading being too light, to raise the temperature sufficiently high. ), or perhaps if bad fuel is causing an unusual rate of soot accumulation.



It is possible that the 3 temperature sensors built into the system ( I am not speaking of your EGT-sensor) are somehow transmitting info to the ECM which it uses to compile a time-at-temperature record, which may then trigger AR (active regen), if the ECM judges that there has been insufficent high-temp operation for a given % of the time. [ This last is conjecture on my part,... I do not yet understand the function of these sensors. There are also 3 oxygen sensors, which MAY be transmitting to the ECM to let it know if the catalyst is doing its job of producing oxygen(by chemical "reduction" of the combustion products) in sufficient amounts to combine with the soot to form CO2, and permit its being exhausted with other gases. ]



Anyone with full-or-partial knowledge of the function of these sensors,... please speak up



So, re. what you were wondering about,... I think you are correct, in that active regen(AR) will NOT occur if operating conditions are such that it is not neccesary,... i. e. , when passive regen (PR) alone can do the job.



This is the apparant performance so far on my own truck. I have not experienced a high-temp indicative of AR so far in the first 754 miles. (of course something could change the next time I drive it.

 

[Wolfy]

Wofly,

I have the same conditions as Jim. With my pickup I have not had it reflashed, nor have I had any problems with the truck. Always started and have not had any indication that the DPF was near full, overhead reads "System OK". Received the truck on June 1, 2007, I have 747 miles on the truck so far.

I did install a pre-turbo pyro, drilled and tapped it's location. Boost gauge using boost bolt that was custom made for the heater grid and intake thickness, shank needed to be 1. 250" inches long. Fuel pressure gauge and isolator installed between filter and CP3 pump. I have installed a big line kit between the fliter and pump using 1/2 fuel line and #8 pushlock fittings. Factory fitting/Ducan's QD had an . 125" ID and the fuel line was 3/16 ID. Fuel pressure at idle 9 PSI, at cruising speed 70 MPH at 7 PSI, WOT it drops to 5. 5PSI. May need a Lift Pump installed??

My EGT readings driving the truck to work, whick takes about an hour, at 70 MPH on cruise, the EGT will vary from normal 800-850 to 1200. This is on level freeway no hills and empty. Every ten to eleven minutes my EGT will increase to 1200-1250 for about 2 to sometimes 3 minutes and then return to 800-850. There has been times as long as 15 minutes before my EGT increases to the upper level. Also, when the EGT increases at this speed, there is a sound that acompanies the increase in temperature EGT. It sounds like an air compressor (one that is installed under the hood) Don't know if anyone has ever heard of one installed on a OTC before. You can hear when it comes on line and offline to fill the tank for the brakes. That is the closes thing I can explain the sound too. It is coming from the location of the A/C compressor on my truck, I have looked in the Service Manual for these trucks and have not found any details relating the A/C pump to the Emissions.

Would this be concidered a normal condition? Should I have the ECM reflashed with REV. A? I to am worried about pulling my trailer if my EGT are that high empty.

Wolfy thanks for the Regen/ TSB posts, good to know.

Hi Smole, (Thanks for the thanks,... you're the first, I think.



" Every ten to eleven minutes my EGT will increase to 1200-1250 for about 2 to sometimes 3 minutes and then return to 800-850. "



Think about this. If you are in AR 2. 5 minutes every 10, your truck is operating in AR, and using extra fuel to do it, 25% of the time.



This seems high to me. My truck has not done it once, to my notice, in the first 754 miles,... and I certainly would have seen anything happening anywhere near this often, for these periods of time. My rig is either performing well,... or I am riding for a fall!



Don't know about the noise. I can imagine that there would be a different sound when higher temps force more expanding-from-heat gases out the pipe (afterburner-style),... but would be surprised if it was noticeable from the seat. ( This is only a WAG.



" Fuel pressure at idle 9 PSI, at cruising speed 70 MPH at 7 PSI, WOT it drops to 5. 5PSI. "



I have installed a fuel-pressure "idiot light" from Diesel manor. I am told (not by DM, with whom I will check this out) that it is set to light-up when pressure drops below 7psi. Presumably this indicates that pressures below this level are considered inadequate in some way.

I suggest you look into this further.



Sorry I couldn't offer more specific answers. I'm an amateur.



BUT,... regarding the "REV. A" flash,... the TSB makes clear that it is intended for your truck(2500/3500, 6. 7L built on/before June 11).

I would definitely GET IT!



If you have not read this entire "understanding regeneration" thread, I would do so. Everything I have learned so far is in here,. . hopefully more will be added as info becomes available. I am adding "edits" to the original two-part post as we learn, so re-reading that portion from time-to-time may be advisable.



Best wishes,

 

[CUMMINZ]

My thoughts exactly

The majority of my 3000 miles so far have been grunting. I would think that the computer is probably in 100% contact with all the sensors all the time. With me at or near the max EGT most of the time I would not think it would trigger a regen. My knowledge (dumb understanding) would say that the last sensor inline does not know whether the heat is from 26k of pulling or a regen cycle. As long as the proper measure of gas it is looking for is attained.



CUMMINZ

 

[Wolfy]

The majority of my 3000 miles so far have been grunting. I would think that the computer is probably in 100% contact with all the sensors all the time. With me at or near the max EGT most of the time I would not think it would trigger a regen. My knowledge (dumb understanding) would say that the last sensor inline does not know whether the heat is from 26k of pulling or a regen cycle. As long as the proper measure of gas it is looking for is attained.



CUMMINZ

[ I know what you meant, but be nice to yourself, any understanding at all is not "dumb",... and most all understanding is "incomplete", when how much there is to know is considered. Some degree of ignorance is inevitable and universal. We're all "students"! ]



But the last (temp)sensor WOULD know if the ECM had instituted un-needed/inappropriate AR, dumping raw fuel into an already-sufficiently-hot situation,... making it TOO(damagingly) HOT,... and The ECM could use this "knowledge" to advise the driver of a need for corrective service.

 

[MCummings]

The turbine is DOWNSTREAM from the EGT sensor(exhaust stream-wise), ... therefore the actual temp AT THE TURBINE (which is closer to the DOC - the source of the increased heat levels, when acting upon the additional injected fuel) MUST BE HIGHER!



Higher than the gauge-indicated 1400-1500 deg!



This is (according, again, to Banks) definitely a POTENTIAL DAMAGE-TO-THE-TURBINE situation. [ Note - The color-indications for temp ranges on the ISSPRO gauge are as follows,... green(normal) to 1050,... yellow (high, caution) to 1250, red(too-high,danger) to a max reading of 1500 deg. ]

The turbine being downstream has nothing to do with it. The catylists, and filters all raise the temperature, just the fact of teh turbine being downstream, does not mean it is hotter. Put a post-turbo gauge on there and check back.



Also, basing your idea's of what EGT is dangerous on the color of a gauge is ludacris. I won't even begin to compare how I feel about that.



The latest marine 5. 9 is safe to operate at 1400*.



Merrick