Dodge Cummins Diesel Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Ride of the Month Challenge!

1 - 20 of 20 Posts

·
Registered
Joined
·
112 Posts
Discussion Starter #1
The various EGR deletes all end up leaving the EGR valve unplugged which throws codes. Since it's going to throw codes anyway, what if you just unplug it? Does it leave the valve open or closed?

The ODBII monitors show the %EGR with the CMD EGR PID which is defined as 'the normalized percentage of exhaust gas being recirculated'. I see it on the Insight range from 0.0 - 94.9%, and I would interpret 0.0 to be the valve is closed. Right?

Dealer says keep EGR system clean by 'getting on it hard', but when I aggressively accelerate or put a load on it, the CMD EGR% drops toward 0.0. If the valve is closed when I'm 'getting on it hard', then that doesn't really force much through it. ????

Also have seen many say the EGR system is necessary to reach the temps required for regen. From the TSBs, the temp necessary for regen is 500, and once it reaches 500, the extra fuel is dumped into the exhaust stroke to cause the catalyst to bump it up above 1000. When a regen is in progress, my Insight says CMD EGR% is 0.0, so it's not using it in a regen anyway once it gets to the initial 500. So it is really needed? Wouldn't you be able to get it up to 500 without the EGR?

Sorry if these are stupid questions. I'm a computer science person by day, but studying hard how all this works.
 

·
Washington Chapter Vice President
Joined
·
5,055 Posts
If you unplug the EGR valve and the EGR tries to kick on the butterfly valve will close in the intake horn and starve the engine for air. I was looking at the plugs the other day and there are 8 different wires going into the EGR valve so it isnt gonna be a easy connector to fool.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #3
If you unplug the EGR valve and the EGR tries to kick on the butterfly valve will close in the intake horn and starve the engine for air. I was looking at the plugs the other day and there are 8 different wires going into the EGR valve so it isnt gonna be a easy connector to fool.
Right - should have realized that since the sticky EGR delete in the performance section (thanks btw!) has you remove the butterfly valve. So in normal operation that butterfly valve is never used just to limit intake, but only to help force EGR? (and really not missed in the EGR delete)
 

·
Registered
Joined
·
135 Posts
I think there are multiple issues surrounding the EGR system.

First, on most systems (I have not quantified this on the 6.7) , the valve is closed at rest. At rest meaning engine off, valve unplugged, etc. I think this system uses a 3 phase linear actuator motor that operates against spring tension.

Second, I believe 0% means closed. Closed being no EGR.

I have to wonder what is being accomplished by the EGR delete procedure. (Other than, of course, getting rid of lots of weight and clutter) Someone else weigh in here is I am missing something.

I know inherently, you might think the dilution of the intake mixture with exhaust gas would compromise performance. I have not actually quantified whether it does or not. I do know that the addition of exhaust gas during some engine-run RPM's can be benificial. The EGR concept is that if you add exhaust to the intake stream, you add an inert gas (exhaust) which lowers the combustion chamber temperature during the flame front propagation event. This lowers the peak combustion temperature. The effect of this action helps control the engine knock event. Traditionally, because of EGR, we can advance timing of fuel or (spark on a gasser) to develop increased low end and acceleration power. Lowered peak combustion temperatures also helps reduce NOx formation.

Curiously, however, the use of EGR, while it helps control NOx; accelerates the formation of soot. This sounds kind of like those prescription medications, there are "side effects"

Overall, as I mentioned I have not measured whether this allows us an overall power increase or not, so don't misconstrue my comments to mean EGR delete is useless. At this point, I don't know. I do know, at times, it is benificial.

The system operates at idle and low speeds and during low end acceleration. During heavy acceleration or hard running, traditionally it is off. (That makes me question BillG's dealer's comment that if you run it hard it will keep it clean) Maybe since it is closed more- less soot will be formed- ??? Not sure about that.

Someday, if we ever get a 6.7 into our dyno labs, we can measure effects.

Again, I have to wonder what correlation EGR has with the Re-gen event. I am having a hard time associating EGR with increased EGT's since its main function is to LOWER combustion temperatures as low speeds.

This is a curious issue- no doubt!
 

·
Mr. Vehicle Destroyer
Joined
·
11,910 Posts
It makes perfect sense that the EGR is closed during REGEN. You have to look at the purpose of regen. It is to essentially make fire after the combustion process is complete. To make fire you need two things fuel and oxygen. If you leave the EGR open during this time you are NOT taking in a full fresh charge and as a result you will not have any oxygen to fuel the fire after the combustion event is complete. SO in order for the fuel injected into the exhaust to burn it needs what little left over oxygen is still in place after a 100% clean air charge burn. The egt's climb as a result of the extra burnt fuel not as a result of any action by the EGR system.

I also don't think its a matter of the DPF clogging up either when the EGR is removed since the engine burns cleaner all the time. I think the problem arrises when the SCR gets plugged up. One of the after treatments is a Selective Catalyist Reduction filter. I don't really know how it functions but it is there to reduce the amount of NOx emmissions. With the EGR off the truck emits a much larger amount of the NOx compounds and I believe will cause this part to fail.
 

·
Washington Chapter Vice President
Joined
·
5,055 Posts
You make very good points. I dont believe there is any power gain in doing the EGR Delete. And most people have seen lower EGTs since removing the EGR. That and the fact there is no more soot running through the engine to plug stuff up are the main advantages.
 

·
Registered
Joined
·
331 Posts
There would have to be a advantage power wise to deleting the EGR with cooler intake air right? You would think without crappy HOT exhaust air entering the motor you would then only be getting cooler fresh air which should help with power.
 

·
Mr. Vehicle Destroyer
Joined
·
11,910 Posts
Fuel = power to a point. Without adding any more fuel you aren't going to get any more power. With that being said however, there may be 5-7 HP you can free up by doing this just from getting a more complete burn of the fuel that is being injected.
 

·
Registered
Joined
·
5 Posts
I removed the EGR from my engine last weekend. It is amazing how much cooler my egt's and my intake temp are with this removed. It reduced my egts about 150 degrees. My intake would normally run 110-190 degrees and now I have not seen over 95 degrees, and that was idleing in a drive-thru. The engine seems to be more responsive and seems to have more power, not to mention no more soot going into the intake, it was nasty. I like it better with it off.
 

·
Registered
Joined
·
34 Posts
You may have created another problem - remember that the DPF needs to sustain 1000+ degrees for oxidation during desoot(regen) Some of that is sponsored internally in the DPF during the burn off, but is driven up by EGT.

Many of us are having regen problem sbecasue we aren't pulling heavy loads adn our regen attempts are failing even at 55 mph over distance.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #11
You may have created another problem - remember that the DPF needs to sustain 1000+ degrees for oxidation during desoot(regen) Some of that is sponsored internally in the DPF during the burn off, but is driven up by EGT.
But is it a problem? EGT has to reach a certain temp to kick off the regen, but is EGR really needed to do that? The EGR valve is closed during regen, so it isn't needed to keep the temps up once a regen starts. So as long as we can get the temp to 500 degrees without the EGR, we can delete the EGR, stop the extra soot, and still manage to keep the DPF clean.

Also, I read in another forum that there is a third stage to the regen: desoot, desox, and denox. But the Insight doesn't show (yet?) denox. So, if there really is a denox cycle, then we can also clean the extra NOxs created by deleting the EGR.
 

·
Registered
Joined
·
479 Posts
You go Bill! I think you know as much as anybody right now. I was thinking today that Dodge ought to consider a "low soot" reflash that would change the operating parameters for those owners who have experienced significant and repeated soot issues. This might entail abandonment of 2010 level compliance for the subset of trucks that can't operate successfully under the current ECM programming. Of course the trucks would still need to be emissions compliant for the year of manufacture but not the 2010 numbers. Maybe that would give Dodge/Cummins enough latitude to scale back the EGR volume or take other measures that reduce soot while accepting slightly higher NOX values.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #13
I have to wonder what is being accomplished by the EGR delete procedure. ... Curiously, however, the use of EGR, while it helps control NOx; accelerates the formation of soot.
That's it - it's all about the soot. I've kept my dpf clean, etc., with a little Insight into what's happening, but I just had my turbo replaced because of the excess soot.

The system operates at idle and low speeds and during low end acceleration. During heavy acceleration or hard running, traditionally it is off. (That makes me question BillG's dealer's comment that if you run it hard it will keep it clean) Maybe since it is closed more- less soot will be formed- ??? Not sure about that.
Thanks! That's exactly where my head is. You can slow the sooting of the EGR system, but you can't really stop it or clean it without a removal & soak.

So while I believe I can manage the dpf (if I keep it on there), I can't see a way to properly keep the EGR clean and still keep the turbo viable.
 

·
Premium Member
Joined
·
713 Posts
You go Bill! I think you know as much as anybody right now. I was thinking today that Dodge ought to consider a "low soot" reflash that would change the operating parameters for those owners who have experienced significant and repeated soot issues. This might entail abandonment of 2010 level compliance for the subset of trucks that can't operate successfully under the current ECM programming. Of course the trucks would still need to be emissions compliant for the year of manufacture but not the 2010 numbers. Maybe that would give Dodge/Cummins enough latitude to scale back the EGR volume or take other measures that reduce soot while accepting slightly higher NOX values.

They have. It is called AX.

AX reduces the amount that the egr lets in the intake side. Also uses the Egr Less.

Thats why most problems are related to early 07.5. Because AX did not come out till Jan.08

Also is why people that delete the egr that have AX are not having fuel knock anyone.:thumbsup
 

·
Registered
Joined
·
112 Posts
Discussion Starter #15
I was thinking today that Dodge ought to consider a "low soot" reflash that would change the operating parameters for those owners who have experienced significant and repeated soot issues. This might entail abandonment of 2010 level compliance for the subset of trucks that can't operate successfully under the current ECM programming. Of course the trucks would still need to be emissions compliant for the year of manufacture but not the 2010 numbers. Maybe that would give Dodge/Cummins enough latitude to scale back the EGR volume or take other measures that reduce soot while accepting slightly higher NOX values.
I'm right there with you. The soot issues are the only thing I don't see (legal) a resolution for at the moment. Everything else appears to be manageable with care and attention.

They have. It is called AX.

AX reduces the amount that the egr lets in the intake side. Also uses the Egr Less.

Thats why most problems are related to early 07.5. Because AX did not come out till Jan.08

Also is why people that delete the egr that have AX are not having fuel knock anyone.:thumbsup
Mine's an 08, but maybe I had an old flash. I think they still have work to do because it seems to me that the soot is on an uphill climb regardless of how you drive or what you tow - unless you block that EGR.
 

·
Registered
Joined
·
5 Posts
As i posted above, i removed the EGR system. My truck puts out far less smoke on all levels of the Edge, this has to be due to a better combustion process in the cylinders with a cooler and more dense air charge going in the intake. My truck has the original flash from build date Aug,07 and I havent had the G30 done either, I dont get the knock that many have talked about with the EGR delete. Before the delete the EGR sytem would do its thing pretty much at anytime, sometimes idleing, sometimes running around town, and sometimes actually working the engine such as pulling a grade at 80 mph.
I think the DPF would actually get plugged faster with the EGR sytem intact than without it. Of course without the EGR the engine would be putting out more NOx. The one thing I do know is this engine runs far better with the stock exhaust and the EGR removed. Much better throttle response, mileage, engine runs smoother etc. Sorry for being long , just thinking out loud
 

·
Registered
Joined
·
34 Posts
You mentioned that your EGT was down by 150 degrees as a result of removing the EGR valve.

The Regen will cancel if the Cat3 sensor drops below the 500 degree range - but oxidation doesn't occure completely untill the DPF gets up to +1000 ( 1200 is better ).

In watching my regen and DPF status, unless I can get EGT to run upwards of 1100 pretty consistantly, the DPF wont stay above 1000 long enough to effectivly reduce the soot.

In some cases it will knock it down by .5 or .8 - but rarley takes it down into the 3.x range or lower.

If I can get EGT to stay in the 1200 degree rang - oxidation occures much faster and more completly..... ( dpf score down to low 3.x)

Just thinking about what your drop of 150 gegrees in EGT may do to the effectivness of your regen cycle...

If I'm wrong with my understanding - point me in the right direction.
 

·
Registered
Joined
·
382 Posts
Guys,
First off I want to thank everyone for their input. You guys are brave because removing the EGR is just like removing one piece of the emissions puzzle. Everything on these trucks work together. And believe me I would like to remove it all and have it look like my old 5.9 under the hood.
I would think that removing the EGR would affect the ECM look-up table for timing values. I guess I am still sorting through all of this stuff in my head. I am anxiously waiting on an EGR delete kit that will allow for some software fooling and help. Good luck to all of you guys that have removed it. I just hear so many stories of fuel knock with the removal because of the timing. Possibly having the AX flash will be a better solution until the kit becomes available. Once again I enjoy reading and learning from you guys that have done it. I appreciate the honest experiences with the removal. I prefer to hear the negative and positive effects of modifications. Thanks again.
 

·
Premium Member
Joined
·
713 Posts
I'm right there with you. The soot issues are the only thing I don't see (legal) a resolution for at the moment. Everything else appears to be manageable with care and attention.


Mine's an 08, but maybe I had an old flash. I think they still have work to do because it seems to me that the soot is on an uphill climb regardless of how you drive or what you tow - unless you block that EGR.
For 08 's I think it is AF. Not poistive on that since I dont have an 08.
 

·
Premium Member
Joined
·
713 Posts
You mentioned that your EGT was down by 150 degrees as a result of removing the EGR valve.

The Regen will cancel if the Cat3 sensor drops below the 500 degree range - but oxidation doesn't occure completely untill the DPF gets up to +1000 ( 1200 is better ).

In watching my regen and DPF status, unless I can get EGT to run upwards of 1100 pretty consistantly, the DPF wont stay above 1000 long enough to effectivly reduce the soot.

In some cases it will knock it down by .5 or .8 - but rarley takes it down into the 3.x range or lower.

If I can get EGT to stay in the 1200 degree rang - oxidation occures much faster and more completly..... ( dpf score down to low 3.x)

Just thinking about what your drop of 150 gegrees in EGT may do to the effectivness of your regen cycle...

If I'm wrong with my understanding - point me in the right direction.
His truck does not go into regen anymore.
He has a 5" TBE with module.
 
1 - 20 of 20 Posts
Top