From GM: "To ensure optimal performance, the system must undergo periodic "regeneration" to release accumulated soot from the filter. The regeneration process uses heat to burn off the soot and, in most cases, is performed automatically." (emphasis added)

From Patrick's post on the DPF: "unloaded and iding alot forces our engines to go into manual regen. driver pulls over and activates regen. takes about 45 min."

I wondered what GM meant by "in most cases". What does everyone think about pulling over for 45 minutes to manually regenerate the DPF? It sounds like a disaster to me.

Patrick - is this as bad as it seems?

:badidea:

That is going to be an issue with the newer trucks and until someone comes up with a fix for that people are not going to be happy. Going to have to find a way to bypass that. They are trying too hard to limit emissions and are going to ruin alot of things for people wanting new trucks. Makes me glad I bought an LBZ..

Ditto!!!

I can't see you having to pull over and stop for 45 mins, but it would not surprise me. I had a chance to talk to a design engineer the other day who worked on the DPF team. He said ECM decides when to clean based on pressure sensors on the input/output side of the filter, and a coil through the middle does the rest. He was pretty vague. The system was in use and in a test truck. Didn't get much of a chance to snoop. All looked like LBZ stuff except DPF.

I thought it just added fuel injected into the particle trap to burn off buildup.

Sawsall....

I thought it just added fuel injected into the particle trap to burn off buildup.

That's what I thought too. So does this mean you could be on your way to work in heavy, grid-lock traffic, and end up having to fight your way over to the shoulder, or the nearest offramp if there's no shoulder, and let it run for 45 mins while calling your boss to explain why your particle trap made you 45 mins late again? :)

I don't know, Maybe I should rethink (again) being one of the first to get an LMM, and just get an LBZ & wait & see how things sort themselves out with the new trucks.

Sawsall....

):h That's what I was thinking - that's how I'd rather spend those 45 mins, but the ECM would probably know what I did :)

Ummm....... No Thanks, I'll stick to my LLY...:duh:

You might want to check this out, slide #9
http://www.cemamerica.com/doeevents/DEER/Presentations/Tuesday/Plenary/2006_DEER_Potter.pdf

slide 8 says there is post injection for regen.

slide 8 says there is post injection for regen.


EGR?

My impression was an internal coil caused regen....

Theres no way it will make you stop for 45min. I think that it will just light up a dash light telling you it is on and other than that, no driver input is needed.

Sawsall....


HAHA!

:exactly:

Should be fun when it gets real hot... I know of a couple guys that have had regular cats on gas trucks catch the truck on fire in wheat and barley fields. That thing will have to get way hotter than a regular cat. Can't be good when you are in a field with any sort of tall grass...


I know the guys building the fire truck and such bodies for the heavy trucks with the new setup said now they have to really protect the exhaust stack because it was melting the aluminum bodies...

I think the way it works is by detecting when the regeneration needs to be done and then give the driver an indicator. The driver then needs to drive the truck above a certain speed for something like 20 minutes for the system to burn off the soot. (it occurs approx. every 30k mi)

You do not pull over to do this!! You need to be moving above a certain speed due to the heat produced.

What's unclear is what happens if the driver ignores this burn off procedure and how long a time window does he have to do this.

P.S. I wish someone would clarify this once and for all. There's a lot of false info out there.

Should be fun when it gets real hot... I know of a couple guys that have had regular cats on gas trucks catch the truck on fire in wheat and barley fields. That thing will have to get way hotter than a regular cat. Can't be good when you are in a field with any sort of tall grass...
.

This was exactly my first thought. Tough enough to keep a dry stubble/wheat field from burning and now this.

We had a similar setup on a scoop tram at work before. Also on a couple tractors. It was a early type of system that had to be plugged in to regenerate it. 1/2 the time we would get calls about no power and it would be because it wasn't regenerating correctly.

Now we are going to be getting a new system that should do it by using exhaust heat. We will see what happens.

The engineer I talked to said the DPF was plugging on the test truck we saw. That was why he was along for the ride. To figure it out. He gave very few details though.

DPF regeneration is made by very late post injections. (There are no additional injectors!).This post injected diesel burns up particles inside the DPF. You will not take notice of it, you don't have to stop.

The post injection will create dirtier oil in the crank case and lower fuel mileage. I wonder what purpose the "intake throttle will serve?

From what I have seen, the regeneration will happen when the computer senses a back pressure increase. Most of the time this will happen at highway speeds.

The computer will inject a small amount of fuel during the exhaust stroke of each cylinder to bring the particle filter up to approximately 2800 degrees.

What scares me the most is having a 2800 degree particle filter under the truck. This is a time bomb waiting to happen.

That is going to be an issue with the newer trucks and until someone comes up with a fix for that people are not going to be happy. Going to have to find a way to bypass that. They are trying too hard to limit emissions and are going to ruin alot of things for people wanting new trucks. Makes me glad I bought an LBZ..
x2 but a LLY;)

I can't wait to see how this DPF thing is going to go down. 2800 deg. under a truck is just insane. May as well just take the plow off my truck and idle for a minute in my customers driveway to melt the snow .

Nick

Nothing an aftermarket exhaust won't fix...........:D

They will ruin the truck markets with the nonsense.

Watch the used truck values increase and the new truck values tank.

They will be loading them up with either tax credits or incentives to move them.

I saw the 5.3 V8 get's 20 mpg in a crew cab 1/2 ton silverado........

Gas is already cheaper than diesel.

Watch the people start switching.

:eek:

If the truck still has to burn the particulate matter eventually, does it really burn cleaner over the life of the truck or just 98% of the time. It might just be me, but I dont see the point in letting all collect in a filter for 30k or whatever and then burning it all at once.

The truck will be burning cleaner all the time. One the computer brings the particle filter up to 2800 degrees, the matter collected will be incinerated. They claim that the released burned matter is actually cleaner than the engine.

We will have to see.

that take care of strait pipe with all the sensors

read that when you get to around 50+mph, and thinks your going to be in steady driving will do it every so often. lot of city driving with no long hiway driving from 10-30K miles will go into a limp mode(SEL) so DLR will have to clean DPF. was told EPA required whole system to be linked so fingersticks won't work and wire seals installed on components to prevent unlicensed emissions work. going to be mess, europeans have had lots of vehicle fires with systems they use. ULSD and new oil grade should reduce time that DPF needs to be cleaned(i wonder if that crap is actually required) and MPG should drop from regen. atleast don't have nozzle in exhaust like cummins that should be fun when it goes out.

I have been told that the emmission work will be a nightmare to fix if some thing goes wrong. The way the systems will be checking each other, I don't know if any of it will be able to be bypassed.

I read that ULSD is the only fuel you can use. Wonder how well biodiesel will work with this system?

Biodiesel is not a problem, since it has little or no sulfur. The ULSD was needed so they could use these particle filters, sulfur will clog the ceramic pores. Supposely Isuzu has been running this basic soot filter in Japan for two years. I hope these things work, because think of the headache it is going to be for the tractor/trailer rigs. I bought a 2007 classic, I have a feeling this one (DPF) will take sometime to sort out. Then the new regs kick in 2010.

Biodiesel is not a problem, since it has little or no sulfur. The ULSD was needed so they could use these particle filters, sulfur will clog the ceramic pores. Supposely Isuzu has been running this basic soot filter in Japan for two years. I hope these things work, because think of the headache it is going to be for the tractor/trailer rigs. I bought a 2007 classic, I have a feeling this one (DPF) will take sometime to sort out. Then the new regs kick in 2010.

So I take it GM is starting early, so they have it perfected by 2010??

The reg for 2007 kick in Jan. 4, 2007 any diesel engine manufactured on or after that date has to meet the 2007 particle standard. The 2010 standard is another step up on even less emisssions. There is "talk" that urea solution will have to injection to lower the levels to the 2010 standard.

I have been told that the emmission work will be a nightmare to fix if some thing goes wrong. The way the systems will be checking each other, I don't know if any of it will be able to be bypassed.

ANYTHING can be bypassed with enought time and determination :D :D :D

ANYTHING can be bypassed with enought time and determination :D :D :D
:exactly:what he said!

I just don't want to be behind one of the new diesels when the DPF is being regenerated. :eek:

My new LBZ is starting to look better, and better, and better. Bill Martin

Nothing an aftermarket exhaust won't fix...........:D

They will ruin the truck markets with the nonsense.

Watch the used truck values increase and the new truck values tank.

They will be loading them up with either tax credits or incentives to move them.

I saw the 5.3 V8 get's 20 mpg in a crew cab 1/2 ton silverado........

Gas is already cheaper than diesel.

Watch the people start switching. :eek: true....... but hook up a trailer, your 20 goes to 8, and your driving range is suddenly less than 200 miles...... :rolleyes: :cool:

ANYTHING can be bypassed with enought time and determination :D :D :D




:exactly:

Some info you guys might find interesting.
I have some personal insite on the DPFs. I worked on a test stand for one of the material suppliers a few years ago.

Regeneration of the filters occurs at around 600 degrees C exhaust temperature, about 1112 degrees F for us on the American side of the borders. So you would have to see more than 1120 degrees at the DPF for regeneration to occur. I saw videos that showed filters regenerating in less than 90 seconds, more like 30 seconds. Granted that was at a simulated run speed, not idle, and the filter was not loaded to it's maximum capacity. I would think the 45 minutes is a WORSE case scenario.
Ideally I think you will see pressure sensors on each side of the filter, these will measure pressure drop across the filter. When the pressure drop reaches a preset value, the ECM senses the need for a regeneration cycle.

Day to day driving and using your right foot may even be enough to get a small regeneration cycle going.

There have been several variations on systems to add heat to the exhaust. Systems like a coil of tubing in the exhaust that adds fuel to the exhaust, post turbo, which burns and raises temperature. I don't think you will see electric heaters that cause regeneration, cause they require alot more current then the electrical system will supply. I have also heard about ECM's that have two "tunes" in them, when a regeneration is required the ECM switches, EGTs go up, and regeneration occurs.

I agree with all of you on here though, if we are going to defeat this monster, it will take some time and alot of experimentation. This is one of those EPA watch dog items that they are going to be keeping their eyes on. Don't be suprised if this is one of those things they check for in the states that do emission checks.

This is why new trucks and new computers suck. Imagine if the computer that controls the length of time that regen happens fails and your running around with a hot ass system all over.

Some info you guys might find interesting.
I have some personal insite on the DPFs. I worked on a test stand for one of the material suppliers a few years ago.

Regeneration of the filters occurs at around 600 degrees C exhaust temperature, about 1112 degrees F for us on the American side of the borders. So you would have to see more than 1120 degrees at the DPF for regeneration to occur. I saw videos that showed filters regenerating in less than 90 seconds, more like 30 seconds. Granted that was at a simulated run speed, not idle, and the filter was not loaded to it's maximum capacity. I would think the 45 minutes is a WORSE case scenario.
Ideally I think you will see pressure sensors on each side of the filter, these will measure pressure drop across the filter. When the pressure drop reaches a preset value, the ECM senses the need for a regeneration cycle.

Day to day driving and using your right foot may even be enough to get a small regeneration cycle going.

There have been several variations on systems to add heat to the exhaust. Systems like a coil of tubing in the exhaust that adds fuel to the exhaust, post turbo, which burns and raises temperature. I don't think you will see electric heaters that cause regeneration, cause they require alot more current then the electrical system will supply. I have also heard about ECM's that have two "tunes" in them, when a regeneration is required the ECM switches, EGTs go up, and regeneration occurs.

I agree with all of you on here though, if we are going to defeat this monster, it will take some time and alot of experimentation. This is one of those EPA watch dog items that they are going to be keeping their eyes on. Don't be suprised if this is one of those things they check for in the states that do emission checks.

How high are these EGT's going to need to be pre-turbo for this regen to occur however far post-turbo away to get your 1112F in your DPF for regen to occur? I mean just the difference between putting your pyro pre-turbo as opposed to post turbo will net you a ~200deg.F difference in readings so what will happen to your pre-turbo EGT's when you need 1112F maybe 1-2ft. post turbo? please correct me if i misunderstood this statement.

if the 2 sensors don't sense a drop in pressure......its all good.......:ro)

This is why new trucks and new computers suck. Imagine if the computer that controls the length of time that regen happens fails and your running around with a hot ass system all over.

If the computer fails then there are 100's, if not 1000's, of other things that will fail. Do you realize that the accelerator pedal is now just a sensor and not mechanically connected to the fuel distribution system? If the computer fails you go nowhere fast.

I don't understand why the DPF control system is such a significant concern and why everyone wants to blindly eliminate it. Once you get past the rumors and read how the thing really works it sounds pretty innocuous. If it's designed right the only affect is an insignificant increase in backpressure that you won't even notice.

The best thing that ever happened to driveability was computer controlled fuel delivery systems.

I'm more worried about the upcomming 2010 diesel emmision standards then the 2007 LMM w/DPF.

Screw it! We might as well go ahead and plan on an electric/hybrid truck by then (2010).
The main reason we run diesel's is for the pulling power. Our first LB7 blew away our 6.0 gashog, power and fuel wise. Chevy FINALLY made a good truck. Now, they're going in the other direction. All this emission stuff is getting pretty irritating to me.

I was playing around in GM service info this morning and some new info on DPF diagnostics. Looks like a series of P2440-P2450 DTC's will monitor electrical performance across a single DPF Pressure Differential Sensor. However no diagrams or operation description yet, so I can't be certain. Also sounds like manual regen's with Tech 2 will be used in some diagnosis. Sounds like biggest warning there.....do it outside!!

I was playing around in GM service info this morning and some new info on DPF diagnostics. Looks like a series of P2440-P2450 DTC's will monitor electrical performance across a single DPF Pressure Differential Sensor. However no diagrams or operation description yet, so I can't be certain. Also sounds like manual regen's with Tech 2 will be used in some diagnosis. Sounds like biggest warning there.....do it outside!!

Check out post #10, its pretty slow loading the slides.

Screw it! We might as well go ahead and plan on an electric/hybrid truck by then (2010).
The main reason we run diesel's is for the pulling power. Our first LB7 blew away our 6.0 gashog, power and fuel wise. Chevy FINALLY made a good truck. Now, they're going in the other direction. All this emission stuff is getting pretty irritating to me.

I agree, however it's not GM that's doing this, The GOVERNMENT is making the manufactures do this.

My biggest concern isn't in eliminating it, and more so in learning how it works. As a GM tech I get to deal with this stuff every day, with limited info sometimes on how it works or responds to real life situations. But, furthermore as a private shop owner, how do I deal with it in the aftermarket. So I disagree a bit with post #46. A lot of learning goes on in these forums as well!!

Sounds like the guys at EFI or maybe Fingers will need to get into this one. Seems like you could spoof the sensors somehow and then just take a sawsall to the thing but I read somewhere that the ECM is also going to keep track of the last time it had to call for a regen and if it gets to be too long the whole thing will limp. Guess it makes me glad I got an LBZ. As far as the 2010s go they had better make that urea stuff free or mine will only get filled up just in time for my emissions test and not at any other time.

true....... but hook up a trailer, your 20 goes to 8, and your driving range is suddenly less than 200 miles...... :rolleyes: :cool:
I also own a 5.3 and it gets around 20mpg and 14mpg towing.

It will only go to Manual operation if you don only city driving, but if you air the baby out every now and then it should not go into manual mode....

like I said our trucks are runing DPF and when we are loded with 80k 105k 130k lbs we regen on the drive a light comes on telling the driver the engine is regening.
unloded and bobtail the soot levels increase and require manuel regen.
I would assume GM will make the EMC change injection values as your on highway driving. but I would be willing to guess most light duty truck owners drive to and from work and spend time in traffic. this will cause more soot build up.
We in our truck are running a dosing injector into the exhaust flow.The added fuel sprays onto the DPF and heats it up.
on a manuel regen we incorpate a throttle valve to shut air flow into the intake causing exhaust temps to rise.

we have seen issues with our proto type engine because we have the same bosch injectors and this causes regen issues. we also have had cooling issues not alllowing regen.

And to make matters worse, the LMM buyers who get disgusted with it (maybe), will go back to the dealer to get an 8.1L just to get the job done that they need to get done, AND THERE WON'T BE ANY.

i got a question, isant it true that the emissions from a gas motor are more harmful to the envirnment then that of a diesel? i guess people see the soot and black smoke and feel the need to go hug a tree.......

i guess people see the soot and black smoke and feel the need to go hug a tree.......

Hey,

That is exactly why diesels have a bad reputation up here. People se a puff of black smoke, and have a fit, yet the fumes you don't see are worse for the enviroment. The Toronto Media is one of the worst when it comes to being anti-diesel!! It really PCensoredes me off when the media is so stubborn to other types of vehicles because of that!!
Oh Well, there loss!!

Nothing an aftermarket exhaust won't fix...........:D

They will ruin the truck markets with the nonsense.

Watch the used truck values increase and the new truck values tank.

They will be loading them up with either tax credits or incentives to move them.

I saw the 5.3 V8 get's 20 mpg in a crew cab 1/2 ton silverado........

Gas is already cheaper than diesel.

Watch the people start switching.

:eek:

I would switch....but then I couldn't pull:mad:

My brother in law sells cars at a chevy dealer and her said that he was told when this thing has to cycle you have to drive you truck at least 35mph for some amount of miles to allow it to cycle, I am not sure how accurate this info is but he said that the chevy reps told them that this is how this system will work.

Whats really bad is that my 2001 Crew Cab Dually with a 8.1L gets 12-14 all day long and 10 pulling a trailer.

I also own a 5.3 and it gets around 20mpg and 14mpg towing.

Towing what?? Not 20k I bet

I believe in the K.I.S.S method, Keep It Simple Stupid and this new engine sounds way to complicated and asks for lots of problems. Glad I went with the LBZ

Ditto on the LBZ. Thank God my order was accepted in the first part of October. Thanks but no thanks on the LMM.......

I wondered what GM meant by "in most cases". What does everyone think about pulling over for 45 minutes to manually regenerate the DPF? It sounds like a disaster to me.

Patrick - is this as bad as it seems?

:badidea:


Sounds like something that can be fixed with a sawzal and programming.

You might want to check this out, slide #9
http://www.cemamerica.com/doeevents/DEER/Presentations/Tuesday/Plenary/2006_DEER_Potter.pdf


Nice. I don't think my lungs could pass the 2010 emission standars.

That is going to be an issue with the newer trucks and until someone comes up with a fix for that people are not going to be happy. Going to have to find a way to bypass that. They are trying too hard to limit emissions and are going to ruin alot of things for people wanting new trucks. Makes me glad I bought an LBZ..

I love my new 06 LBZ. I'm 'gonna let you brave guys try out the LMM and report back. Can't wait to see how you get along.... I might be ready for an 08 or 09. Bill Martin

The truck will be burning cleaner all the time. One the computer brings the particle filter up to 2800 degrees, the matter collected will be incinerated. They claim that the released burned matter is actually cleaner than the engine.

We will have to see.
2800*s Yikes, I fortell more than one of these trucks catching fire. Just one little squirt of oil on the colllector/incinererator and POOF.:rolleyes:

Towing what?? Not 20k I bet
no not 20k, towing 20k should be left to a freightliner, dmax will tow it, I know, Ive done it. The only problem is trying to stop the 20k:eek:

I as well am glad that i got my LBZ before this emissions bulonga...... as i see it its much like taking a gallon of gas and throwing it on the ground (current emmisions) and the new ones will only mix 100 gallons of water with that gas and then throw it on the ground. It doesnt make sense in my opinion, but not only will it hurt or truck market, but also think of the calss 8 semi's and such, they have the same bull to work with, thats where i think well see money, in shipping and such, just my .02! Jason

Nothing an aftermarket exhaust won't fix...........:D

They will ruin the truck markets with the nonsense.

Watch the used truck values increase and the new truck values tank.

They will be loading them up with either tax credits or incentives to move them.

I saw the 5.3 V8 get's 20 mpg in a crew cab 1/2 ton silverado........

Gas is already cheaper than diesel.

Watch the people start switching.

:eek:

LOL i already switched! I sold the lly and got a new 07 crew SLT loaded. Awesome truck and im within 4 mpg of my diesel. i can handle lower mpg when truck is about 13-15K cheaper. I love the truck. guess i better change the sig.

Duramax 6.6L Diesel Engine (LMM)

http://216.182.211.32/techlink/images/issues/dec06/images/3x3/fig1_sm.jpg
figure 1
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figure 2



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figure 3
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figure 4


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figure 5



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figure 6
hope this helps,



A new diesel engine is available for 2007 (fig. 1). It’s the Duramax 6.6L (RPO LMM). This engine is being released to conform with 2007 US EPA diesel emission regulations, which require a 60% reduction of NOx and a 90% reduction of particulate matter.
http://216.182.211.32/techlink/images/issues/dec06/images/6x6/fig1.jpg
This new engine has been designed to be the most powerful and cleanest Duramax Diesel ever offered in the Chevrolet (Silverado, Express, Kodiak) and the GMC (Sierra, Savanna, Top Kick) models.

A number of design strategies have been put in place to meet these new emission regulations. These include both software and hardware:

- Exhaust particulate filter

- Intake air valve

- Revised EGR

- Exhaust tailpipe cooler

- ECM calibration

- Revised injector nozzle flow

- More robust internal engine components and a more efficient turbocharger

EMISSION CONTROL COMPONENT HIGHLIGHTS (fig. 2)

http://216.182.211.32/techlink/images/issues/dec06/images/6x6/fig2.jpg
A Diesel Oxidation Catalyst (DOC)

B Exhaust Particulate Filter (DPF)

Diesel Oxidation Catalyst (DOC) -- Reduces hydrocarbons (HC) and oxides of nitrogen (NOx), carbon monoxide (CO) and odor-causing compounds. It also turns the majority of emissions into water and oxygen.

Exhaust Particulate Filter (DPF) -- Traps the particulate matter (solid particles that appear as black smoke) from the engine exhaust before they can be emitted into the atmosphere.

During the regeneration process (explained later), the DOC is heated above its normal operating temperature by a different engine calibration strategy that includes additional fuel injection pulses. The extra heat created by the DOC is used to increase the temperature of the exhaust particulate filter (DPF). The DOC helps obtain and sustain the required temperatures during regeneration.

EXHAUST PARTICULATE FILTER (DPF) OPERATION

The DPF is installed in the exhaust system behind the catalytic converter, and its appearance resembles the catalytic converter. The filter element (fig. 3) is made of porous, catalytically coated silicon carbide, which allows the exhaust gases to pass through, while trapping the solid matter from the exhaust. This decreases particulate matter (soot) and eliminates exhaust smoke. The DPF collects particulates while the engine is running.

http://216.182.211.32/techlink/images/issues/dec06/images/6x6/fig3.jpg
To prevent clogging, particulate matter is periodically burned off, leaving ash and yielding carbon dioxide and water. This process is called particulate filter regeneration.

DPF REGENERATION CONTROL (fig. 4)

http://216.182.211.32/techlink/images/issues/dec06/images/6x6/fig4.jpg
A Pressure sensor

B Exhaust differential pressure sensor

C Temperature sensor

D Particulate filter

The ECM keeps track of operating conditions to determine the amount of particulate accumulation, and periodically initiates a regeneration process.

Pressure Sensors -- The exhaust differential pressure sensor (EPS) measures the pressure difference between the inlet and outlet of the DPF filter. When the pressure difference has increased above a calibrated threshold, it indicates a high particulate loading condition. The ECM then commands a regeneration event in order to restore the DPF.

The exhaust pressure differential sensor is also used to monitor the filter for cracks or holes in the filter substrate.

Exhaust Gas Temperature Sensors -- During regeneration, two temperature sensors are used to monitor the process. One sensor, located ahead of the DPF, measures the temperature of the exhaust gases leaving the Diesel Oxydizing Catalyst and entering the DPF. This temperature measurement is used by the ECM to control fuel injector flow that is used to maintain temperatures necessary for regeneration. A second temperature sensor, located after the DPF, helps the ECM monitor and regulate the regeneration temperatures and helps protect the system.

DPF REGENERATION OPERATION

Regeneration may occur under several circumstances, called Active Regeneration, Passive Regeneration and Service Regeneration.

Active Regeneration

The regeneration operation is controlled by the ECM, which keeps track of the mileage driven, the amount of fuel consumed, the hours of operation and the exhaust differential pressure.

When the conditions are met for regeneration to occur, the ECM enters a different engine calibration strategy that includes additional fuel injection pulses. This heats the DOC is above its normal operating temperature and regeneration begins.

For the process to complete satisfactorily, the vehicle must be operated continuously for approximately 18 minutes at speeds greater than 30 mph (50 km/h) to efficiently clean the filter. If the engine is allowed to return to idle during this time, the idle speed may be elevated slightly and the operating sound may be different. This is normal, and the driver doesn’t need to do anything different.

During regeneration, the exhaust temperature increases (greater than 500° C), which converts the particulates into harmless gases and ash. The DPF is then clean and ready to filter particulates again.

Driver Notification -- If normal driving does not provide the necessary conditions for regeneration to occur, the pressure differential continues to increase across the exhaust filter. The ECM will illuminate a CLEAN EXHAUST FILTER message on the instrument panel Driver Information Center (C/K only).

When this occurs, the owner manual and a label placed by the driver’s sun visor instruct the customer to drive the vehicle under the conditions necessary for a regeneration to take place until the CLEAN EXHAUST FILTER message no longer appears on the DIC.

Reduced Power -- However, if the CLEAN EXHAUST FILTER message is ignored, the ECM will eventually illuminate the MIL and the Reduced Power lamp. The engine enters the Reduced Power mode, which will require the vehicle to be serviced.

Passive Regeneration

Passive regeneration occurs when exhaust gas temperature is elevated above 300°C
(575° F). These temperatures may be reached when the engine is under heavy load.

Service Regeneration

Service regeneration is performed with the Tech 2, and is used to clean a soot loaded filter during a dealership service visit.

DEALING WITH REGENERATION TEMPERATURES

The exhaust system has been designed to deal with the temperatures involved in the regeneration process. On long wheelbase models, for instance, a heat shield protects the rear axle shock absorbers. All models have an exhaust cooler at the end of the tailpipe
(fig. 5). A vacuum created by the exhaust passing through the openings draws in cool air, which mixes with the exhaust gases. Cooled exhaust exits the tailpipe.

http://216.182.211.32/techlink/images/issues/dec06/images/6x6/fig5.jpg
A Exhaust cooler

B Exhaust flow

C Air flow

D Cooled exhaust

IMPORTANT -- There are times when a DPF service regeneration must be performed at the dealership. THIS MUST BE CONDUCTED OUTDOORS. The shop exhaust system will not handle the heat.

DIESEL FUEL AND OIL REQUIREMENTS

The LMM diesel engine requires ultra low sulfur fuel, which limits sulfur content to 15 ppm (parts per million). It also requires use of oil which conforms to the CJ-4 standard established by the American Petroleum Institute (API). This oil offers lower oil consumption and reduces limits for phosphorus, sulfur and ash. Low ash oil is needed to extend the life of the Engine Particulate Filter, as well as to reduce the formation of engine sludge and deposits.

IMPORTANT

Use Ultra Low Sulfur Diesel Fuel (ULSF) only (fig. 6). The emission control hardware may be damaged if high sulfur level fuels are used.

http://216.182.211.32/techlink/images/issues/dec06/images/6x6/fig6.jpg
Do not use Low Sulfur Diesel Fuel.

Do not use Off Road Diesel Fuel.

Use only engine oil that has the API classification of CJ-4, which is formulated to work properly with the Diesel Particulate Filter.

Vehicle Modifications -- DO NOT modify any exhaust systems or engine control components, unless it’s GM approved.

1. Use Sawsall a little before point A and a little back of point B.
2. Insert a resistor of ___ ohms between pressure sensor A and pressure sensor B. (to show that it always has the right amount of backpressure.
3. Weld in a "pipe" that matches cutout from step #1.
4. Temp sensor C may always be ignored since a regeneration event is never called for but it could require a spoof depending on what the PCM monitors. (TBD)

Just kidding. This system doesn't seem so bad.

1. Use Sawsall a little before point A and a little back of point B.
2. Insert a resistor of ___ ohms between pressure sensor A and pressure sensor B. (to show that it always has the right amount of backpressure.
3. Weld in a "pipe" that matches cutout from step #1.
4. Temp sensor C may always be ignored since a regeneration event is never called for but it could require a spoof depending on what the PCM monitors. (TBD)

Just kidding. This system doesn't seem so bad.

LOL! We probably will see black market kits like that for sale.
I agree, it doesn't seem nearly as bad with the more info we've gotten since several months ago. Still a bit of a worry though. I wonder what happens if you have to shut down during an active regen (like when you arrive to work), does it just pick up where it left off when you start back up? Wish they'd just switch to cleaner burning Biodiesel, then maybe we wouldn't even need something so complicated. Thanks Stacks04 for posting that info! :thumb:

I still havent hared a difinitive answer from anyone on a person like my buddy who drives 4 miles ot owrk every day (pulls a toy heauler in summer) waht will his truck do during the whinter when hes only driving to work. What will skin temps be??? Driving over wheeat stubble and rows of hay? truck fire/???

the Ecm uses many other sensors to help with the timing of a regen. I supose if one where to custom burn a program you may be able to disable the DPF diag. and fool the ECM to thing the sensors are there and the DPF is running a optimal levels.
The regen must complete its self. so if a shut dowm occurs the regem will continue on next key cycle. I am sure Gm Logic is to regen with engine at operating temp.
Our trucks my be different but the supplier of components are the same. So I assume things are close to the same.

Stacks04, first off thanks for the info. Second, is there a muffler or did the filter take its place . thanks Mike :)

This is all very interesting, the entire key to getting around it is when EFI or a similiar company can figure out how to program the new ECM's to totally cut out this part of the process. The questions about extreme temps during regeneration are troublesome. I lost most of 6 acres of trees and half my house when some guy turned around at the end of my field and his exhaust caught the grass on fire. I may very well be one of the first guinea pigs with the new LMM. All it will have to pull my LB7 single cab to the race track. :D