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Discussion Starter · #1 · (Edited)
I'm starting this thread to share information regarding soot accumulation on emissions equipped trucks. There's a lot of mis-information around soot accumulation statistics so I was hoping to we could flush out some hard data here. If you have a scan tool like the Edge CTS that can display soot grams, or have questions about soot accumulation then please jump in here.

These are the questions I most commonly get along with my answers:

1. How often does the truck go into regen?

My experience has been that there are 2 common triggers for regen. The truck will initiate regen once it reaches 44 grams of soot in the trap or travels ~700 miles since the end of the last regen. Whichever of these events occur first will start a regen. The regen seems to last until the soot load goes below ~10 grams or so and the driving conditions no long promote regen.


2. How long does it take to regen?
Mine typically takes about 1 mile per gram of soot. So if the DPF is at 44 grams, and regens down to 5, it generally takes about 40 miles. Of course it'll take longer if the cycle is interrupted.

3. How quickly does soot accumulate?

It depends on usage. On the highway, it may be 1 gram every 25-30 miles. Mixed driving might be closer to 20 miles, and of course on the dyno things move a little faster. The weird thing is that the counter jumps quickly between 1-10 grams (maybe one gram per mile), counts slower from 10-19 grams (10 miles/gram), and then seems to count from 20-up much slower (20-30 miles/gram).

4. How much extra fuel does regen take?

My best guess comes from the mileage adjustment I see under steady state operation. For instance. My trip this weekend averaged 19.7 MPG mixed over 700 miles. The truck entered regen at 700 and regen-ed for 40 miles. At the end of regen the DIC showed 19.2 MPG. If I'd done the 740 mile trip without regen at 19.7 MPG I would have used 37.56 gallons. At 19.2 MPG, I used 38.54 gallons - a difference of about a gallon or 2.6% more fuel.

5. Does tuning affect regen frequency?

Of course it does. The tune needs to be clean for the regen frequency to be kept in check. Our latest tunes are as clean or cleaner than stock. This 515HP tune is the first one I've hit 700 miles between regens. Even driving the truck aggressively seems to have very little affect on the soot counter. The early tunes I tested on dyno seemed to load the soot trap very quickly on the higher HP settings (superchips/HS/Hypertech). If driven reasonably, they intervals weren't noticeably longer - but if hot-rodded you could expect the soot counter to move quickly.


I know how our 2 test trucks act, but I know I could benefit from more data and I think the community as whole could too. If you have any first hand experience to add to these answers please do. If there's anything I can clarify, please ask.

Thanks,
Nick
 

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Good data!!
 

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I purchased your tunes 2 months ago and have put about 2k miles on the truck mostly running the sport economy tune. I have been seeing between 175-250 miles with mixed driving and avg 14 mpg. While pulling my 18' aluminum boat to my duck hole on the highway using the light tow tune I have seen it as low as 100 miles between regens but still 13.8 mpg(75mph). The only time I have ran the mpg tune was an all highway trip to Louisiana (while my truck was completely stock) from houston to south Louisiana and saw 18 mpg(hand calculated) and 300 miles between regens. Not complaining at all about the tunes, I love the way the truck drives. I called you guys today and got the new tunes and immediately after loading noticed a difference in soot levels and mpg while running around town tonight on sport econ. I drove around 15 miles tonight and the soot level did not even budge. Excellent job on the new tunes guys. If anyone is looking to keep emissions intact and run a tuner I highly recommend duramaxtuner.


Sent from AutoGuide.com Free App
 

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Discussion Starter · #4 · (Edited)
Tx Driller 13,

Glad to see you in here. I appreciate your candid review our first cals and look forward to your review of our updated files. A truck on 35's, hot rotted and towing is a great test of soot control. Did you mention the tire size update when you contacted us the other day? All new orders and revisions should be adjusted for tire size (BOnus: This will help true up your MPG numbers).


Nick
 

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No I forgot to mention it to Justin. Ill give you guys a call when I get back from offshore.
 

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I have a 2011 LML. Completely stock. The ODO says ~ 34,000 miles

I have only ever seen my truck go into a regen once.

Now granted, I have been on several long road trips where I have not been the only one driving (asleep in the passenger seat is where I'm at if I'm not driving)

Am I missing something here. People seem to have regens a lot more frequently than what I'm seeing.

EDIT: I'm going by what I see on the DIC, not by way of any tuner or monitor (CTS)

Mark
 

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Discussion Starter · #7 ·
Mark,

The factory dash gives no indication of regen unless there is an abnormal event. You'd need a CTS or the like to see if you're in regen.

A good tipoff is if you notice the trucks idle increase 100 RPM at a stoplight or in park - telltale regen sign.

Nick
 

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Mark,

The factory dash gives no indication of regen unless there is an abnormal event. You'd need a CTS or the like to see if you're in regen.

A good tipoff is if you notice the trucks idle increase 100 RPM at a stoplight or in park - telltale regen sign.

Nick
Got ya. Thanks for clearing that up! I'll keep an eye on it for a while and try to report back.
 

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Great info nick!!!

I am a diesel newbie and I have 2800 miles on my bone stock 2013 lml, I drive in town enough that I have noticed each regen via the high idle that occurs during the process.

I have gone into regen right at 700 mile intervals. That makes me think that I am not reaching 44 grams. Which begs a question, is there a way to adjust when the computer tells the truck to regen? I have had a regen last as short as 15 miles, means the filter wasn't very fouled at all. Have also had a regen last much longer but it was mostly town driving so that may have been the contributing factor.

Thanks again for the very informative post!!!
 

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I have about 1300 mile on my new 2013. Its a Cab & Chassis model ran one regen when odometer hit 800 miles. Fuel economy effects soot accumulation. I see that when pulling. Ran the original DPF on my 2010 LMM for 470k. Regens became shorter. Replaced DPF the truck regens every 400 miles.
I wonder if the new trucks there is a differnce in size of DPF between short box and long box.
I screwed up drove my dads new 2013 CC short box this week for 1100 miles and forgot to bring the CTS. Could of compared it to my Cab & Chassis
 

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These are the questions I most commonly get along with my answers:

1. How often does the truck go into regen?


2. How long does it take to regen?


3. How quickly does soot accumulate?



Thanks,
Nick
1. My truck goes into regen about every 350-500 miles highway mountain driving and towing a light trailer (about 3500lbs single axle).

2. It takes about 30 minutes to regen on average.

3. I agree on the soot build up, the more there is the longer it takes to reach regen status.

One thing I would caution is that when the truck is in regen status DO NOT PARK IN DRY BRUSH or Grassy areas that may be in close contact with the exhaust components due to fire risk.
 

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Excellent info!
 

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I just noticed my first regen this week (high idle), I was around 1800 miles... Im sure I had some in the past but never really knew it or understood. Im slowly absorbing the diesel knowledge from ya'll... let the good times roll.
 

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1. My last regen was approximately 580 miles, about 70% hiway driving.

2. The regens seem to last 30 to 35 miles while on the hiway. My last one was interrupted twice and completed when the soot count got down to 6. The previous regen went down to 3 when it was all hiway driving and it wasn't interrupted. The soot count was at 44 both times when it started. I have the Edge set to alarm at 44 so that I know when the regen is going on.

3. I agree on the soot accumulation, it goes up fast right after the regen is done, then tapers off as the count gets higher.

Rich
 

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You can monitor the post DPF Egt sensor and watch the temp soar when in regen. I know with my LMM that soot builds faster when truck is pulling a load then just truck. I'm sure the rate of fuel to the the engine affects soot accumulation.
 

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Bump and sub'd. In the middle of testing regen cycles in Tuned and Stock.
 

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I have a 2012 GMC Sierra stock. Has 16000 miles. I use it in my landscaping business. Pull a trailer almost everyday. Its not a lot of weight i would say anywhere between 1800 and 2800 pounds a day depending on what we are doing that day and what we have on the trailer. It is mostly city driving across town on the interstate. I do run the exhaust brake most of the time. Do not use trailer mode very often don't think the trailer is heavy enough for it. Am I wrong? I'M thinking i get better fuel mileage with out it on with this small amount of weight. I have been keeping track of my regens for about the past six months. I go into regen every 100 to 240 miles. Last about 40 to 45 miles. I feel this is to often to go into regen. I have called several dealers in my area and all they will say is they have never heard of this and for me to bring it in for them to look at it. Problem is i need truck everyday we work. I would have to rent a truck to pull the trailer while mine is in the shop. Also do not know what dealer to trust in my area. Has anyone else had there truck regening this often or heard of one regening this often?
 

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I don't have a CTS or any accurate way of telling when in Regen other than my pyro. It is analog and the probe is mounted on the passenger manifold. I can definitely see 100-150* higher egt's when in regen.. Also have the telltale high idle and wicked smell if sitting still. I guess I could be missing some, but I do keep an eye on the pyro when driving.
At any rate I have recently started keeping track and have seen 750 miles between them with mostly highway and some highway towing(approx. 5k). They usually last about 30 minutes or so.
My truck has just crossed the 10,000 mile mark.
 

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My truck used to go about 450 miles between regens then since 35,000 miles it was down to 300 miles between regens, one in a great while (it's happened only 3 times) I've gone 500 miles between regens. I've had it to the dealer numerous times to see why some trucks go 700 miles between regens and mine goes only 300 miles. At first it was, "There are no codes stored, so everything is fine". Then after bitching long enough, they got GM involved and checked for boost leaks, checked injectors for being balanced (I thought they had to be removed for this, but according to the service manager it can be read on the Tech II), checked the DPF for efficiency - the tailpipe is clean so it's doing its job. Basically it's running fine. They had no answers other than telling me that if I drive in stop and go traffic or idle a lot soot will build up faster causing more frequent regens. I told them that I agree, but that doesn't apply to me - I drive 110 miles a day round trip at speeds from 65-80 mph so why are me regens so frequent? They didn't have an answer. I asked them if it's possible that one or more of the programs in the computer are bad or corrupt thus causing the frequent regens or even causing the engine to run rich, but as far as the computer knows, it's running fine? Maybe just clear out the memory in the ECM and reload it with the latest update? They dismissed the idea that if something was wrong a check engine light would come on. But I told them what if the computer had bad info and didn't know it was wrong? It was quickly dismissed.

I do want to get a tune, but while my truck is under warranty I want this issue corrected, but after GM got involved, they won't do anything. I don't want a tune to compound this issue as this would void my warranty.

I see why so many people delete their trucks.
 
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