E.G.R. and the Diesel - Q&A

[A Johnson]

Doc, I'm supposedly certified on the "02" Cummins product. What does that mean? As far as I can tell it means they paid me to watch a couple virtual college CD Roms and answer enough of the test questions correctly to pass. Have I ever worked on one? Nope, not yet. Am I disgusted? You bet. I hope others,(R. E. Miller?) are getting more hands on training then me.



Heres what I remember from the CD Roms.

If an EGR valve gets stuck open or closed, first of all there will be a check engine light, as the valve has logic to tell the ECM what position its in, in relation to engine speed, throttle position etc. The valve also uses a motor for operation

Pretty much any check engine light will be in conjunction with a power derate.



Physical effects of an open valve would be low power, if there is not enough oxygen in the cylinders of course it won't run.



A stuck closed valve should run fine but low power due to the check engine light and derate.



I don't believe there are any oxygen sensors in the exhaust, if I remember right, the ECM adjusts everything based on algorithms of the current operating conditions, and assumes emissions are in spec.



Additional hardware includes EGR cooler, Egr valve, turbo speed sensor, Variable Geometry Turbo (VGT), EGR mixer in the air inlet.



(I'm going by memory so help me out guys, with things I missed. )



As with any new product, training usually ends up being done in the field on real problems, and if this new system is typical of others, the cause and effect of broken parts may not be what the factory tells us they will be. It seems there are always several new pages of troubleshooting advice a year or so after introduction.



I really don't think EGR is a big deal, its only a few more parts and once we understand better how they all interrelate troubleshooting should be pretty straight forward.



I'm more scared of Cats' ACERT technology, and the implications for me if EPA decides that is the way to go.



A Johnson

 

[Doc Tinker]

Thanks,



Now... The next question is: We all have intercoolers to cool the intake air as much as possible, which increases power. How is it possible to cool the exhaust gasses enough to not reduce power? I presume that the gasses don't really cool down that much but power won't be affected during midrange operation, or maybe the real plan is that midrange power loss isn't crucial and is traded off?



Doc

 

[Doc Tinker]

Next question: Is the design of a diesel EGR Valve different from a gas model? I ask, because I've seen old EGR valves from gas engines that were plugged with carbon. The diesel creates more particulates so I figure the buildup would increase. When that happens, would the EGR valve become ineffective?



Doc

 

[Doubleclutch]

All you guys from the wrong side of the rockies, and I'm the only one responding from the state that has had the egr valves (96-98). Lucky for me I've got a '96 made in '95 (215 hp). I think I can only add a little to the fine discussion above: The recirculated exhaust is deficient in oxygen and therefore displaces the incoming Oxygen rich air charge, reducing combustion temperatures and NOx. The reduced Sulphur (15ppm fuel mandate was probably related to Tpyles's observation about Sulphuric acid build-up in the head. Well Doc, you really went "fishing" on this one!

Greg

 

[R.E. Miller]

Originally posted by Doc Tinker

Thanks,



Now... The next question is: We all have intercoolers to cool the intake air as much as possible, which increases power. How is it possible to cool the exhaust gasses enough to not reduce power? I presume that the gasses don't really cool down that much but power won't be affected during midrange operation, or maybe the real plan is that midrange power loss isn't crucial and is traded off?



Doc

Doc, it really isn't. Due to the emissions requirements/operating parameters of egr, we lost the signature 600. So not only are we subjecting the exhaust pipe to tighter standards, we also must make the combustion process more efficient for both improved emissions and more power to offset the loss. I did see a few pictures of the new trucks (yes, new trucks) that are out that have front ends big enough to accomidate the larger cooling system parts.



Russell

 

[R.E. Miller]

Trying to help.

Doc and folks,



From a good source:



EGR



Exhaust gas recirculates through the engine to reduce the amount of oxides of nitrogen emmited from the engine. The exhaust gas is cooled as it flows through an egr cooler, and then is mixed with the compressed fresh air from the turbocharger before entering the intake manifold. EGR is introduced to reduce the amount of in-cylinder oxygen available for combustion while maintaining the same amount of flow through the engine. Exhaust gases present during the start of combustion are very stable and have a slow reaction rate. They absorb heat during combustion, resulting in lower in-cylinder peak flame temperatures, and therefore, lower NOx emissions.



Food for thought

Russell



P. S. notice the word usage..... in-cylinder specification in relation to lower temps... hmmmm.

 

[TPyle]

Doc,



The power isn't reduced because the fuel maps are going to be such that they provide more fuel. Hence the 2-5% reduction in MPG that Cummins, Mack, Volvo, Detroit, CAT (only with the bridge engines). Here's something to really think about. In 2007 trucks operating in certain "polluted" areas of the country will be emitting cleaner air out of the stacks that the air thats drawn in through the breathers. Will the EPA issue tax credits for these rolling"scrubbers"?

 

[timjones]

Originally posted by Doubleclutch

All you guys from the wrong side of the rockies, and I'm the only one responding from the state that has had the egr valves (96-98). Lucky for me I've got a '96 made in '95 (215 hp). I think I can only add a little to the fine discussion above: The recirculated exhaust is deficient in oxygen and therefore displaces the incoming Oxygen rich air charge, reducing combustion temperatures and NOx. The reduced Sulphur (15ppm fuel mandate was probably related to Tpyles's observation about Sulphuric acid build-up in the head. Well Doc, you really went "fishing" on this one!

Greg

Basically what happens is that in order to lower unwanted emissions you need to "detune" the engine, It seems backwards IMHO but this is the gist. Add fuel(cools burn), Retard timing(higher temp lower nox), Lower cyl pressure/compression/boost(lower temp). It's the same game they have been playing with in gassers for 30 years(1973). :{

The egr is not the end of the world like some are trying to make it, but a step in the direction that needs to be taken. The CAT or similar system will come in to effect and egrs will fall by the side as they have in gassers. The good thing with diesels is that they only look for NOx, the bad news is thats what diesel live on.



I personally get tired of having to wear gas mask all the time , it gets real hard to sleep.

 

[fest3er]

The nice thing about an EGR with electrical feedback is the circuit can be replaced with something that tells the PCM exactly what it wants to see. So whilst the EGR stays shut, the PCM is led to believe the EGR valve is operating as desired. And when the Air Nazis stop you, you flip a switch and the valve goes back to work.



Fest3er

 

[AMF]

egr engines

So what year engines have egr's?

 

[rbattelle]

None, so far ('04. 5's only have a catalyst).

 

[EBottema]

Guys, all this chat is nice but why dont you just buy a 12v and tell th air quality agency in your area to shove it? Thats the easiest solution. You can always rebuilt a old 12v and repaint, restore one of them in the years to come!!

 

[Big_Daddy_T]

If we are burning more fuel to do the same job. Are we not forced to harm the environment just in another way?

Diesels run way to lean at low rpms. So egr is a caveman technology way of removing o2 from the cylinder. The end result is we rape the planet 3% faster. Whats the point. Friggin epa.

So accert is meant to go the long haul. All the way thru 07. Good to know. Ballsy step on cats behalf. A gamble that has cost them a lot of money but could reap much, much more. Unusual in this cost cutting, cheapest way out market.

 

[nickleinonen]

Originally posted by Big_Daddy_T

If we are burning more fuel to do the same job. Are we not forced to harm the environment just in another way?

Diesels run way to lean at low rpms. So egr is a caveman technology way of removing o2 from the cylinder. The end result is we rape the planet 3% faster. Whats the point. Friggin epa.

So accert is meant to go the long haul. All the way thru 07. Good to know. Ballsy step on cats behalf. A gamble that has cost them a lot of money but could reap much, much more. Unusual in this cost cutting, cheapest way out market.

camless diesels or ones with variable cam timing [needs to be 2x cam though] will make the egr obsolite. a camless B series diesel is what i want my next diesel to be [±10 years from now]

 

[rbattelle]

Originally posted by nickleinonen

camless diesels or ones with variable cam timing [needs to be 2x cam though] will make the egr obsolite. a camless B series diesel is what i want my next diesel to be [±10 years from now]

Put me down for one too!!