I know most of you know all about DPF and regeneration but heres some more info. If its already been posted, sorry.


Duramax 6.6L Diesel Engine (LMM)


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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
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.

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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)


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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.


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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)


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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.


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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.


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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.

- Thanks to Frank Tornambe

looks to me like if you removed the DPF but left the pressure sensors in place, the differential pressure would never get high enough to trigger a regeneration cycle.

And the solution is:

I prefer PLASMA:muahaha:

glad i am impatient sometimes and bough the LBZ

And the solution is:

Thats what I'm talking about....

Bypass a couple sensors and straight pipe here we come.

Gentlemen: please note that the sensors also "look" for cracks and holes in the substrate. It might be important to find out what the computer does when it thinks it has a hole or crack. Depending on what the computer does, bypassing it or removing it might not be an option. Man, do I hope I'm wrong.

If it can be figured out, somebody on this sight will be the first one. Of that I'm certain...

Gentlemen: please note that the sensors also "look" for cracks and holes in the substrate. It might be important to find out what the computer does when it thinks it has a hole or crack. Depending on what the computer does, bypassing it or removing it might not be an option. Man, do I hope I'm wrong.


How could it possibly do that? A pressure sensor does one thing and one thing only, it reads pressure. They simply have a pressure sensor before and after the DPF and the ECM subtracts the two to find the pressure drop across the filter. When the pressure drop increases to a certain point, it triggers the regen cycle.

It looks to me like you could replace the whole exhaust with a straight pipe system, and just zip tie the pressure sensors and temp sensors to the frame under the truck. There would be no difference in pressure, and no need for a regeneration cycle.

the pressure sonsors and the ecm are calibrated so for ex, the pre sensor reads 50 psi the after reading with the dpf installed will have an automatic drop of say 5psi. just from the substrate material. when a hole or crack is present the pressure drop would be less thus causing a cel.

The pressure sensors could be connected to different points on the exhaust that just happen to have pressure differentials similar to an unclogged DPF.

A larger pipe at a cooler temp. will have a lower pressure than a smaller pipe with higher temp. gas flowing through it.

Also, the exhaust differential pressure sensor turns mechanical pressures into electrical signals that probably can be simulated.

How could it possibly do that? A pressure sensor does one thing and one thing only, it reads pressure. They simply have a pressure sensor before and after the DPF and the ECM subtracts the two to find the pressure drop across the filter. When the pressure drop increases to a certain point, it triggers the regen cycle.

It looks to me like you could replace the whole exhaust with a straight pipe system, and just zip tie the pressure sensors and temp sensors to the frame under the truck. There would be no difference in pressure, and no need for a regeneration cycle.

That sounds like the easy way, but I would think that the front sensor would have to see some back pressure. The PCM must have software that wants to see a little back pressure all the time.
My guess would be some kind of simple plug in place of the sensors. Sometimes the software battle can be worse than the hard part replacement.

The PCM must want to see the temp sensors change with engine temp. Cant help but think if they just read ambiant air temp all time it would trip a code.

Bypass a couple sensors and straight pipe here we come.



:exactly:........... :D

I frikken Love this website. We havnt even seen the trucks in person yet and we already have guys trying to find ways to bypass all the exhaust emmissions crap on the new 07 HD Trucks. :D

Kudos :thumb: to all you guys out there already working on ways to bypass that exhaust junk!!! Your work and research is much appreciated.
:beerchug:


For all the guys out there worried about the new emmissions stuff on the LMM, theres not a doubt in my mind that the guys on this site cant out-smart and bypass these sensors and crap. It may take a little time, but it will get done...

:grd:

And the solution is:

:agreed: LOL

yes the pcm wants to see pressure from the restrictive exhaust system. the sensor though is only a three wire here's how it works


The exhaust pressure differential sensor (2) measures the pressure difference between the inlet and outlet of the exhaust particulate filter (DPF) filter. When pressure difference has increased above a calibrated threshold, a high particulate loading condition is indicated. The engine control module (ECM) will command a regeneration event in order to restore the DPF. If the pressure differential continues to increase across the exhaust filter without a regeneration event the ECM will illuminate a DPF lamp or send a message to the drivers information center (DIC) referring the customer to the owners manual. The owner’s manual will instruct the customer to drive the vehicle under the conditions necessary for a regeneration to take place. If these lamps and messages are ignored the ECM will eventually illuminate the MIL and revert to Reduced Engine Power which will require the vehicle to be serviced.
The exhaust pressure differential sensor wiring consists of the following circuits:
• A 5-volt reference supplied by the ECM
• A low reference supplied by the ECM
• A signal supplied by the differential pressure sensor to the ECM--The voltage is relative to the pressure differential changes in the particulate element. The ECM converts the signal voltage input to a pressure value.
The exhaust differential pressure sensor sample lines (5) are connected before and after the DPF. To provide the pressure sensor with accurate backpressure measurements, the DPS sample lines should have a continuous downward gradient, without sharp bends or kinks.

It is my understanding that the temp sensors are only used to control the regeneration. If regeneration never happens, then they aren't needed.

What we don't know is if you will get a CEL if the pressure sensors don't register a certain amount of pressure drop. If that's the case we'd have to fabricate the proper signal to keep the PCM happy.

The exhaust differential pressure sensor sample lines (5) are connected before and after the DPF. To provide the pressure sensor with accurate backpressure measurements, the DPS sample lines should have a continuous downward gradient, without sharp bends or kinks.

This is simply to prevent condensation from building in the lines and preventing the pressure sensors from reading correctly.

Ash is a non-combustible by product from normal oil consumption. Low Ash content engine oil (CJ-4 API) is required for vehicles with the exhaust particulate filter (DPF) system. Ash accumulation in the DPF will eventually cause a restriction in particulate filter. Regeneration will not burn off the ash, only particulate matter is burned off. To service an ash loaded DPF, the DPF will need to be removed from the vehicle and cleaned or replaced.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1871460&pubid=1647&evc=sm&cellId=159111#ss9-1871460">Exhaust Temperature Sensor Position 1

The exhaust gas temperature (EGT) sensor 1 (6) is a variable resistor that measures the temperature of the exhaust gases at the inlet of the DPF. The engine control module (ECM) supplies EGT sensor with a bias 5 volts on the signal circuit and a ground on the low reference circuit. When the EGT sensor is cold, the sensor resistance is high, as the temperature increases, the sensor resistance decreases. When sensor resistance is high, the ECM detects a high voltage on the signal circuit. When sensor resistance is low the ECM detects a lower voltage on the signal circuit. Proper exhaust gas temperatures at the inlet of the exhaust particulate filter (DPF) are crucial for proper operation and for initiating the regeneration process. A temperature that is too high in the DPF will cause the DPF substrate to melt or crack. Regeneration will be terminated at temperatures above 800°C (1,472 °F). A temperature that is too low will not completely eliminate the particulates during regeneration. The ECM monitors the temperatures at the DPF inlet and outlet to regulate DPF temperatures.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1871460&pubid=1647&evc=sm&cellId=159111#ss10-1871460">Exhaust Temperature Sensor Position 2

The exhaust gas temperature (EGT) sensor 2 (1) is a variable resistor that measures the temperature of the exhaust gases at the outlet of the DPF. The engine control module (ECM) supplies the EGT sensor with a bias 5 volts on the signal circuit and a ground on the low reference circuit. When the EGT sensor is cold, the sensor resistance is high, as the temperature increases, the sensor resistance decreases. When sensor resistance is high, the ECM detects a high voltage on the signal circuit. When sensor resistance is low the ECM detects a lower voltage on the signal circuit. Temperatures at the outlet of the DPF are crucial to maintaining the integrity of the exhaust particulate filter (DPF) substrate. A temperature that is too high in the DPF outlet will cause the substrate to melt or crack. Regeneration will be terminated at temperatures above 800°C (1,472°F). A temperature that is too low will not completely eliminate the particulates during regeneration. The ECM monitors the temperatures at the DPF inlet and outlet to regulate DPF temperatures.

DTC P0545: Exhaust Temperature Sensor 1 (EGT-1) Circuit Low Voltage

DTC P0546: Exhaust Temperature Sensor 1 (EGT-1) Circuit High Voltage

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Diagnostic Fault Information

Circuit
Short to Ground
Open
High Resistance
Short to Voltage
Signal Performance
Exhaust Temperature Sensor 1 Signal
P0545
P0546
P20E2
P0546
P20E2
Exhaust Temperature Sensor 1 Low Reference
--
P0546
P20E2
P0546
P20E2
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Typical Scan Tool Data

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#tab5-1866411">EGT Sensor 1

Circuit
Short to Ground
Open
Short to Voltage
Operating Conditions: Ignition ON
Parameter Normal Range: -39°C to +999°C (-38°F to +1,830°F)
Exhaust Temperature Sensor 1 Signal
-40°C (-40°F)
1 000°C (1,832°F)
1 000°C (1,832°F)
Exhaust Temperature Sensor 1 Low Reference
--
1 000°C (1,832°F)
1 000°C (1,832°F)
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Circuit/System Description

The exhaust gas temperature sensors position 1 are variable resistors that measures the temperature of the exhaust at the inlet second outlet of the diesel particulate filter (DPF). The engine control module (ECM) supplies a bias 5-volt signal to the EGT signal circuit, and supplies a ground to the low reference circuit. When the EGT is cold, the sensor resistance is low. When the EGT temperature increases, the sensor resistance increases. With high sensor resistance, the ECM detects a higher voltage on the EGT signal circuit. With lower sensor resistance, the ECM detects a lower voltage on the EGT signal circuit.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss7-1866411">Conditions for Running the DTC

• The ignition is ON.
• This DTC runs continuously when the above condition is met.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss8-1866411">Conditions for Setting the DTC

P0545

• The ECM detects that the EGT sensor is less than 0.32 volt.
• The condition exists for greater than 1 second.
P0546

The ECM detects that the exhaust temperature sensor is greater than 3.37 volts for greater than 1 second.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss9-1866411">Action Taken When the DTC Sets

• DTCs P0545 and P0546 are Type A DTCs.
• Normal regeneration will be inhibited.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss10-1866411">Conditions for Clearing the DTC

DTCs P0545 and P0546 are Type A DTCs.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss11-1866411">Diagnostic Aids

• Inspect the EGT sensor terminals for corrosion.
• Measure and record the resistance of the EGT sensor at various ambient temperatures greater than -8°C (+18°F), then compare those measurements to the Temperature Versus Resistance (http://service.gm.com/servlets/CellHandler?CellId=157530&RefDoc=1866411&evc=sm) .
• A short to a separate 5-volt source occurs, this DTC will set.
<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss12-1866411">Reference Information

Temperature Versus Resistance (Exhaust Gas Temperature Sensor)

<A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1847002&pubid=1647&cellid=157530&evc=sm#tab1-1847002">EGT 1 and 2 Sensors

°C
°F
OHMS
Temperature vs Resistance Values (Approximate)
1000
1832
849
900
1652
795
800
1472
738
700
1292
680
600
1112
618
500
932
554
450
842
521
400
752
488
350
662
455
300
572
420
250
482
385
200
392
349
150
302
313
100
212
276
50
122
238
25
77
220
0
32
200
-20
-4
185
-40
-40
170



(http://service.gm.com/servlets/BlobShtml?ShtmlFile=1866411&evc=sm&pubid=1647&cellId=158406&mspsdsubkey=6698#ss12-1866411)

Scott, do you know if during normal operation the ECM will add/remove fuel to keep the DPF at a certain temperature? Any idea what that temperature might be?

maybe we should drive these trucks before figuring out hypatheticle things,guys these arn't even out yet lets see how they run first

This sure sounds like a big pain in the ash :)

This would probably be way too simple to actually work but, might it be possible to just replace the LMM ECM with an LBZ ECM? I'm betting there are too many other differing parts involved, but then, under it all it's basically the same engine as the LBZ, right?

Pain in the ash is right. The LMM will even go into limp mode (reduced fuel) if the DPF gets plugged up. Oh- that could be loads of fun.

It's going to be an interesting year....

Scott, do you know if during normal operation the ECM will add/remove fuel to keep the DPF at a certain temperature? Any idea what that temperature might be?

Like anything with GM sometimes they limit the info to us on what the PCM is really doing. But we do know it changes injector pulse during regen. The PCM is always calculating, so I am sure it figures those sensor readings into the calculations. The sensors always read...so I am sure the PCM is always watching the values.

As far a exhuast temps go I bet they wont change a whole lot from what we have seen in the past. With the exception of a plugged or partly plugged DPF. Maybe slightly higher do to more componants in the exhuast.

Since we have not got one of these new trucks I have been unable to look at typical scan tool values. I did get a glipse of scan tool values during a recent class........ pressure and temp change was very slight.

I will post if we see one of these new LMM early....

what kind of temps will be showing at the manifold to get the DPF up to burn the ash?? And when it is <10degrees F is it going to get hot enought since it is behind the cat? This morning it was 1 degree outside and i was blowing smoke for 15 miles till the pipes warmed up. I am also glad i own a LBZ

what kind of temps will be showing at the manifold to get the DPF up to burn the ash?? And when it is <10degrees F is it going to get hot enought since it is behind the cat? This morning it was 1 degree outside and i was blowing smoke for 15 miles till the pipes warmed up. I am also glad i own a LBZ


That's a good point. We've been having high temps in the single digits the last few days and my LLY has a hard time even getting up to temp. I feel sorry for the guy who has his LMM trigger a regen cycle when its this cold outside. You'd be lucky to get 2 MPG.

With the information I have read here so far, this shouldn't be too hard of a nut to crack. Sensors are fairly easy to fool with analog circuits. If it gets real complicated, a simple embedded CPU can provide the desired signals to the ECM.

With the information I have read here so far, this shouldn't be too hard of a nut to crack. Sensors are fairly easy to fool with analog circuits. If it gets real complicated, a simple embedded CPU can provide the desired signals to the ECM.

So the next generation of Fingerstick is just around the corner??

Need a victim, er, volunteer! to work on.

With the information I have read here so far, this shouldn't be too hard of a nut to crack. Sensors are fairly easy to fool with analog circuits. If it gets real complicated, a simple embedded CPU can provide the desired signals to the ECM.




AWESOME!:rockit: Im really glad Fingers showed up to this post.

Just a note For all of you worried and complaining guys out there about the new LMM motor. This man right here ^ is definately one of the guys who will put your worries and complaints to rest on the new Duramax LMM. ;)

Say for the sake of argument a way is created to bypass all the emissions equipment. What will happen when the time comes to resmog the truck? In California, you would not be able to reregister the vehicle.

Very good and very curious questions guys. Let me try to help answer some of them. Let’s start with removing the filter, pressure sensor, and exhaust temp sensors.
The DPF is flanged on both ends so a straight pipe would suffice, temp sensors are bossed into the DPF pipes before and after the filter so when the DPF goes so does the temp sensors. The Pressure Sensor has pressure lines that are connected before and after the DPF so when the DPF goes maybe the pressure lines go with it, if they don't then a couple of brass plugs in the exhaust pipes will take care of the pressure lines. So now, all the components with the expectation of the Exhaust Cooler, and the Intake Air Valve have been removed.

Now, what are you going to do when all the DPF codes start setting in the ECM? Exhaust Temp Sensors DTCs, Differential Pressure Sensor DTCs, and Too Long of time between regenerations DTC. Yes, there will be a timer that measures the length of time between active regenerations:damnit1: Also when certian performance codes set, the engine will be commanded to operate in reduced engine power? :damnit1: The MIL will illuminate because they are all type A codes. It’s a brand new controller for 2007 so you can’t go back and plug in a 2006 with out a great expense.

Does anybody have the ability to hack into the ECM and disable the DTCs? If the answer is NO, then bypassing the system is not going to be cakewalk.

I agree with BarbarianCoug “What will happen when the time comes to resmog the truck? In California, you would not be able to reregister the vehicle.” OR what will happen when the time comes for an emission test.

I am interested in your thoughts; I just barley touched on some the scenarios that could take place.
:beerchug:

This sure sounds like a big pain in the ash :)

:laugh_exp :exactly: rofl

...and Too Long of time between regenerations DTC. Yes, there will be a timer that measures the length of time between active regenerations

That figures. Everything else could (potentially) be faked by a replacement for the DPF that provided the same nominal pressure drop as an unclogged DPF.

I read elsewhere that (supposedly) sustained heavy loads produce a high enough temp that eliminates the need for regeneration, in that the byproducts are burned off, which would otherwise require a regeneration.

If that's the case, the question is, how long would the ECM expect the longest possible time between regenerations to be?

Keep the parts to put back on for emissions testing.

Jury is still out, but I don't see anything that I can't get around here. No codes. The ECM will never know things are missing.

looks to me like if you removed the DPF but left the pressure sensors in place, the differential pressure would never get high enough to trigger a regeneration cycle.

Good analogy Jolly, but, The ECM will take into account amount of Fuel Consumed, Engine Run Time, Distance Traveled, and few more things that are :secret: too.

Personally i think all of this emissions stuff is totally gay.

I read elsewhere that (supposedly) sustained heavy loads produce a high enough temp that eliminates the need for regeneration, in that the byproducts are burned off, which would otherwise require a regeneration.

Yes, It's called a passive regeneration. But, an active regeneration will still take place anyway base on fuel used, distance traveled and engine run time and couple more things that are :secret:

"If that's the case, the question is, how long would the ECM expect the longest possible time between regenerations to be?"

This is a good question. Time between regenerations is a calibrated threshold, not quit sure, I would like to say somewhere around 8 hours.

Keep the parts to put back on for emissions testing.

Jury is still out, but I don't see anything that I can't get around here. No codes. The ECM will never know things are missing.
The ECM will still command an active regen, and dump extra fuel into the exhaust every so often without causing the same temperature rise as it would during a regeneration, unless that can be turned off (EfiLive for LMM?).

What's your point? The regen isn't a problem other than maybe the extra fuel it uses. Since you end up pushing the regens out to the max by always detecting a clean filter, I see it as a non-issue at this juncture.

What's your point? The regen isn't a problem other than maybe the extra fuel it uses. Since you end up pushing the regens out to the max by always detecting a clean filter, I see it as a non-issue at this juncture.

The point is the ECM will know if the DPF is missing, because it will not detect differential pressure transients from the pressure sensor while driving, nor will it see proper regen temps. So, several diagnostics will run and fail and the MIL will turn on, the ECM will command reduced engine power. Look at it this way P2453 Pressure sensor performance DTCs, P2002 DPF Low Efficiency DTC at the minimum will set. Reduce Engine Power will be commanded by the ECM, You can barely make it to 50 MPH when this happens, god forbid you're on a steep incline or towing a heavy load. You will be forced to go the dealership.

You don't know me too well, do you.
:)

No, I just signed up today, It's nice to meet you Fingers!
:beerchug:
Have a great weekend!

Welcome to the site.

Good analogy Jolly, but, The ECM will take into account amount of Fuel Consumed, Engine Run Time, Distance Traveled, and few more things that are :secret: too.

I think you give the ECM a little too much credit.