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Regen Intervals and noticeabilty

204K views 590 replies 155 participants last post by  DYLDTS 
#1 ·
So you lucky owners of the 2.8L may have had or will soon be having an Active DPF soot incineration. Other than the MPG drop on instant meter in DIC do you notice any other tell tale signs of regen. All my Dmax 6.6L trucks would go thru an active regen unnoticed other than a high idle and slightly more growl from exhaust tone. What intervals are these 2.8l engines doing an active regen ? Thanks in advance .:grin2:
 
#168 ·
Here is an idea for making good use of regen time. Last night, my truck was asking for a regen as I drove in the city. I now had a choice. Waste my time and fuel by heading for a highway or ignore it and hope it doesn't plug up and cause problems later on. I noticed I had half a tank of fuel. I thought, why not find a station with a good price, located on a highway. I checked one of those gas prices websites and it showed a station with the best price but, it was located in town. The site also showed stations on a highway 15 minutes away in an area famous for competitive pricing. I decided to head that way and sure enough, my regen completed just before I got to a station with a great fuel price. Plan your regens for cheap fuel. Much better than a wasted trip to nowhere.
 
#169 ·
My truck only made it 305 miles before I notice a 900 rpm idle, And instant mpg dropped to 20-22. After maybe 10 mins it was back to normal. Ill have to wait and see how long before it does it again.
 
#171 ·
Not to worry. My first regen was at only 380 kilometers. It seems to be common for the first one to happen early. Maybe there is a lot of slow driving and idling during factory and dealer testing, line ups for the train, spray in bed liner shop etc. Also, possible oil residue on the new emission parts attracting more soot. Am I grasping at straws or does this make sense? Later regens seem to come a lot later. I probably didn't notice one or two on highway trips.
 
#170 ·
I had 2 on this tank roughly 525 miles between them, I drive a 70 mile round trip to work/home with a speed limit of 65 with 10 of those miles include a stretch of 45-50mph with traffic lights, so there is plenty of time to regen and its why my mpg's are as good as they are. However my Sierra was getting about 17mpg "in the summer" so a huge bonus there. But yeah, when the regen hits my instant mpg's are around 20. This morning I knew I was going to need to fill before I got to work so when I noticed that my truck was regen I just slowed down so that it would have time to finish before I filled up, I think it actually finished afterwards just before I got to work because my instant mpgs went to almost 40 however my DIC shows for the 6 miles I drove after the fill up that I only got 18mpg.
 
#173 ·
Not sure where of if I posted it but I had Regen happen just after the fuel light came on and I wasn't planning on stopping anytime soon.

Once the light came on I switched the DIC to watch my remaining miles and it went from about 60-ish when the light came on to "LOW" as soon as it went into Regen. So I prolly won't let fuel get that low when I know a Regen is close again. That was scarey
 
#178 · (Edited)
Perhaps, living in NH, it's now getting warmer, and more summer like in temperatures, reducing your engine warm up time, and putting less soot in the DPF every time you start up on a cold motor. Take logs, run notes on ambient temperatures at engine start up time, and get back to us in 5 years. When it's cold out, you can't run biodiesel, it's gel point is too high, at 30 to 40F, it will clog your fuel filter, compared to regular diesel fuel at 7F. I can assure you, biodiesel does not help your DPF at all, or lengthen the miles between regens, it has a higher flash point than regular diesel fuel. High probability it is not all completely catalysed and has residual fatty acids still left in it that do your DPF no good.


If you really want to find out, try this: Run your fuel tank well into reserve, and fill up with 100% biodiesel in the fuel tank. Make the next 4 fillups biodiesel. Log all your regenerations, and routes driven when doing so. Top off with regular diesel, ie good old number D2, B0 fuel. Repeat exact same routes, for 4 tanks of fuel, exact same logs. Then you'll be able to share some educated observations.

It helps to substantiate your claims with blind testing, side by side, by labratory technicians with no interest in the products they are testing. You obviously have a green agenda and some sort of reason you want to promote biodiesel consumption, It's all in your name, Mr. Green Oxygen crew.

I just last week did a trip that was about 800 miles in two days, to go mine some turquoise mineral samples in Nevada. I took my AWD VW TDI Touareg on that trip, and set the cruise control to the legal limit 65mph the whole trip. Weather was a little high in humidity, about 40% the days I was driving. I went 485 miles between DPF regenerations on that trip. Bigger 3.0 liter diesel motor, lighter 5000 # SUV, a lot less load on the motor and working a lot less harder than a Canyon or Colorado. 1 quart of biodiesel added to the last previous fillup, I believe.
 
#180 · (Edited)
You think a renewable energy organization is non biased? :rolls eyes How about if the petroleum industry does a similar test.

Actually, how about asking the manufacturers of your DPF the effects of biodiesel on their product, since they warranty what they build. That might be a little bit less biased.

I can surely tell you what diesel pump manufacturers have to say about biodiesel blends,ie Fatty Acid Methyl Esthers or FAME. They want very little of it running in their Common Rail diesel injections systems, since 2009.

https://www.denso.co.jp/ja/aboutdenso/technology/product/powertrain/files/common_position_paper.pdf
 
#182 · (Edited)
Mileage between regenerations of DPF

It's well known that the engineers of diesel engines and factory tunes try to make a Diesel Particulate Filter active regeneration appear as seamless and unobserveable as possible on these Diesel trucks.

I'd like to hear comment from folks with OBD 2 port readers on the mileage observed between noted DPF active regenerations. You probably have a Scan Gauge 2 or other reader and notice when the engine idle rpms come up a bit when stopped and a regen is occurring. Sometimes you might notice a slightly different burning smell from the exhaust. Your turbo pre inlet temps make spike up, your boost from turbo goes up in temp and your catalytic convertor and DPF will head generally higher than 105F when an active regen is occurring. So with the obd 2 port reader, it becomes quite obvious when a regen is occurring. The temps on the gauge spike quite high.

So the question is, how many miles can you travel between regenerations? Are you stock tuned of aftermarket performance tuned?
 
#187 · (Edited)
Mileage between regenerations of DPF

It's well known that the engineers of diesel engines and factory tunes try to make a Diesel Particulate Filter active regeneration appear as seamless and unobserveable as possible on these Diesel trucks.

I'd like to hear comment from folks with OBD 2 port readers on the mileage observed between noted DPF active regenerations. You probably have a Scan Gauge 2 or other reader and notice when the engine idle rpms come up a bit when stopped and a regen is occurring. Sometimes you might notice a slightly different burning smell from the exhaust. Your turbo pre inlet temps make spike up, your boost from turbo goes up in temp and your catalytic convertor and DPF will head generally higher than 105F when an active regen is occurring. So with the obd 2 port reader, it becomes quite obvious when a regen is occurring. The temps on the gauge spike quite high.

So the question is, how many miles can you travel between regenerations? Are you stock tuned of aftermarket performance tuned?


Why are you starting a new thread when you were already commenting in the previous regen interval thread??

I have an obd reader, I gave you my figures, you didn't like them or believe them because of a "hidden agenda" so you start a new thread? You don't even own one of these trucks. Go somewhere else.


Sent from my iPhone using Tapatalk
 
#183 · (Edited)
Stock tuned...just had a regen on my way home from town, no readers, scans or what ever, just watched my mileage drop to 20-22 mpg going 65mph for about 10-15 minutes. 445 miles since the last regen, my wife said she could smell it.


edit: pretty much 75% highway / 25% City
 
#193 ·
First noticed regen today at 4056km well city driving... Mpgs shot up and was idling at around 925 rpm. Was rushed for work but didn't want to shut down till it was finished. Geared down and got the rpms up to get her nice and hot...could almost feel it when she finished the regen
 
#194 · (Edited)
Just drive normally, don't shift up or down, the ECM will compensate to optimize the active regeneration. You don't need to change anything. The exhaust and turbo boost are plenty hot with enough oxygen at any speeds above 30 mph. The EMC knows what is optimum, regardless of your rpms. It doesn't take much heat to get the DPF burning, what it takes is a little bit of fuel from the 5th injector and for the turbo to pump a bit more air through the motor, into the exhaust, where it fans the heat of the DPF with more oxygen. It doesn't take much engine RPMS with that variable nozzle turbocharger. The turbo does most of the work in doing an active regen, once it's ignited and lit off. It fans the burnoff with plenty of oxygen to complete the DPF combustion burn off process.
 
#196 · (Edited)
More rpms won't make the regen happen any quicker. it's a controlled burn off, it takes time, you can't expedite it. It's controlled by a program, with a whole bunch of parameters. No matter what you do, it takes the same amount of time.

10-12 minutes in VW product, and another 4 to 6 minutes of cool down of turbo and DPF filter, to temps of < 450F before shut down, on a Scan Gauge 2. YMMV on Colorado/Canyon,might take longer, might take less time.
 
#197 · (Edited)
Finally saw my first obvious regen (well I think thats what this was). With well over 2k miles on the odometer, northbound I 5 through southern Oregon Siskiyou.

55-65 MPH, significant decline when MPG suddenly dropped to high teens, low twenties.

MPGs should have been way higher due to most of the stretch was downhill and I was very light or off the throttle.

Only lasted for a few minutes then MPG went back to high twenties, the avg for the trip.

Only thing I had done differently was filled up with HPR diesel about 200 miles prior.

Prior to this I've never noticed any dramatic change in MPG or anything else indicating a regen but I rarely get out on the open road for a significant amount of time.

Soon I'll have my scan gauge programmed to monitor these actions and EGTs.
 
#199 ·
I do mostly city driving and the last couple regens have been happening around 200 miles. The regen is rather quick. The last one was over in less than 9 miles (35 - 45 mph). I was downshifting to get the RPMs up in city driving but after reading a couple of the posts above probably won't bother since it may not be making a difference.
 
#200 · (Edited)
Every regen doesn't take the same amount of time. Sustained driving at 65 mph will allow the regen to finish sooner than sustained driving at say 35 mph. Members who actually own a Duramax Twin will understand.
 
#201 ·
Had a regen start on me today on the way to town to go get some paint supplies for the house. Got to town (20 kms), still in regen. Shut her down , went into hardware store, came out 15 minutes later, fired up truck, pulling out of parking lot regen restarted and lasts for 6 more kms and done. Seems to complete an active regen faster than my 6.6L Dmax. Also this regen came in at 850 kms as opposed to my usual 600 km intervals. I suspect since i have done some towing( 6k lbs) up to the lake (10% grade for 7 kms and 8% grade all gravel for 26 kms)i have had some passive regen going on . Excellent truck on the for washboard roads, rides smoother than any other truck i have driven up there.:smile2:
 
#203 ·
I finally have a better understanding on how DEF Regen Cycle works on the 2.8L Duramax. Since I started to monitor the Regen activities in May, I am always curious why my Regen Interval is around 200 miles versus some other members in the forum have over 300 to 450 miles range. We recently took a trip up to Yosemite and I found my answer during the trip: During a long trip (at least 2 to 3 hours non-stop with highway speed above 65mph), the EGT-11 (manifold temperature) is around 700 to 800, the Passive Regeneration cycles come on more often with the EGT-14 and EGT-15 (Pre and Post DEF) temperatures running above 500 to 600, the Passive Regen keeps the Active Regen from being active much longer. However, if the truck is running a lot of short distances and lots of stop and go traffic, there are little opportunities for the Passive Regen from happening, thus the Active Regen interval is a lot shorter as well.
 
#204 ·
Seems about normal for me and what others have reported, that mostly drive city/heavy traffic commutes. I typically see 180 to 240 miles between active regens, which I'm sure is why even though "good for a truck" I'm typically averaging only 23MPG in such a commute :| On longer sustained cruising it gets much better as you've noted.
 
#208 ·
That's interesting. I know regen will stop when you shift to park. Never tried neutral but I will next time. I guess this means you left the key in the ignition and locked the door with the fob. Weren't you worried someone might smash your window and take your truck or am I missing something here?
 
#212 ·
I just had my first regen at 780 miles. Not near as noticeable as my lml was and also finished much sooner. I couldn't tell it was happening besides smelling something hot and then seeing I was idling a bit higher though couldn't tell without looking. My lml when regent the high idle was noticeable in both sound and the fact the engine would try to move the truck, very noticeable in city driving, I really hated how it could be felt when braking and how the truck would try to move if you weren't holding firm on brakes.

The lml would take a couple days of driving to work (in town) to finish, the Colorado regened just running to a couple stores.
 
#214 ·
The message will appear when an Active regen can not be properly completed after a certain amount of tries, usually due to too short of a drive cycle each time truck was used since active regen started not allowing DPF to reach 1200 degrees to incinerate the soot to ash.. This message appears to force you to run truck long enough to get soot level in DPF down to an acceptable level. If you don't ever see this message then your Active regens have all had time to finish process and you are not prompted to keep operating vehicle.
 
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