EGR - to delete or not delete, plus what happens (if anything) after its removed?

I know what it is and what it does.
The obd system will calibrate slight differences in fuel trims and timing curves.
The cam and crank sensors adjust spark timing accordingly, oxygen and air fuel sensors tell the ecm of a rich/lean condition..
Its obviuosly not lean enough to trip the ecm.
It really doesnt take much to throw a code and honestly if it wanst for the temp sensor the ecm has no clue its even been blocked off.

 

Just curious, but how does eliminating hot exhaust gases cause an increase in combustion temps and higher EGTs? Is the particular gases causing a drop in these temps and when missing it burns hotter, the lean mix from the lack of them, or is it the compensation of the ECU from the o2 readings?

 

Just giving the info that some seem to overlook when they want to remove the system.

Besides, it's not like you're gonna gain power from removing it. It doesn't operate under wide open throttle. So people who claim an increase in power from the butt dyno are likely experiencing a placebo effect.

In short, increases in EGTs, combustion temps, usually a drop in efficiency, and no power gains. Not worth it.

 

I posted a link on how they work on the previous page.

 

well while on paper no one can dispute this "claim" but I just took mine apart to clean it and the TB and the EGR tube itself is only 1/2" ID and the EGR valve is only 3/8" opening so that's all the gas that passes through it when it is open.

now add that 3/8" hole compared to the 4 (in my case) intake ports averaging 1 1/2" in size each and we are only talking about the tiny portion of gas added to the large volume of intake air so all these wild claims of engine knock and ping or melting spark plugs by overheating engines and I call BS on all these wild exaggerations on the world coming to an end if its removed or blocked off.

also since it only comes into use at midrange "cruising speeds" it doesn't operate full time and therefore negates any claims of "running cooler" but it does make some "modest" change on a computer graph somewhere im sure.

now all that said, perhaps there is no real gain to be had by removing one but since issues related to the EGR can cause strange rough idle and hesitation issues in mid range acceleration hesitation (something I have a possible concern about it being an issue) well there can logical reasons to try blocking it off for troubleshooting or removing it just to avoid any such issues.


I wish to ask you guys to tone it down a little and remember we are all just fellow members here who enjoy our tacos and like to help each other so if two of us cant agree then lets agree to not agree and both points have been made and let other members decide who they believe has made their point better ok?

thank you and please continue the comments but with respect for each other

 

Posted berfore I read the article.

Reduced throttling losses. The addition of inert exhaust gas into the intake system means that for a given power output, the throttle plate must be opened further, resulting in increased inlet manifold pressure and reduced throttling losses.
Reduced heat rejection. Lowered peak combustion temperatures not only reduces NOx formation, it also reduces the loss of thermal energy to combustion chamber surfaces, leaving more available for conversion to mechanical work during the expansion stroke.
Reduced chemical dissociation. The lower peak temperatures result in more of the released energy remaining as sensible energy near TDC (Top Dead-Center), rather than being bound up (early in the expansion stroke) in the dissociation of combustion products. This effect is minor compared to the first two.
It also decreases the efficiency of gasoline engines via at least one more mechanism:

• Reduced specific heat ratio. A lean intake charge has a higher specific heat ratio than an EGR mixture. A reduction of specific heat ratio reduces the amount of energy that can be extracted by the piston.[citation needed]

EGR is typically not employed at high loads because it would reduce peak power output. This is because it reduces the intake charge density. EGR is also omitted at idle (low-speed, zero load) because it would cause unstable combustion, resulting in rough idle. The EGR valve also cools the exhaust valves and makes them last far longer (a very important benefit under light cruise conditions).[citation needed]

 

But Wiki isn't the best.

Because ;
Last edited 12 days ago by Guy Harris

 

I merely pulled that link as it was the first one. Here is another. http://www.agcoauto.com/content/news/p2_articleid/207

 

this is what I am thinking but if my rough idle issues persist, I may block it off to see if it may be leaking causing my random rough idle at times

I have already tried cleaning it and while dirty it wasn't "filthy" enough to think its sticking and now that its been cleaned and tested to move easily I don't know if it might be a random valve seating issue since that's not something you can test since its random.

 

Take a moment to consider where your Toyota truck engine spends the majority of its life operating. It's in the mid and lower ranges of throttle position, not wide open. So yes it certainly does lower combustion temperatures.

This isn't a race car folks.

 

I will only say your engine speeds half its life idling in traffic, driveways, parking lots, onramps and offramps, and the other half it finally reaches cruising speeds so your temperature argument is false except to a minute degree as I stated before.

most of us who drive in the city rarely if ever get to the midrange for the EGR to even open and we put the majority of the mileage on our trucks without the EGR even being open to do anything to achieve the benefits it claims to do.

you are talking about a 3/8" sized hole in an intake manifold that is letting 12 square inches of airflow (1.5 x 1.5 = 3 square inches x 4 ports = 12 square inches) so the EGR is using exhaust gas pressure so its not under great force of pressure to supply much if anything so you are talking about it adding very small minute percentages of exhaust into the airflow into the engine

 

My last tacoma went over 100k with it blocked off...
I really dont think its hurting anything..

 

Source: http://www.aa1car.com/library/egr.htm

See bolded.

 

Again, merely stating the facts on how it works, and what happens when it's not there.

 

well I must correct myself, its 3/8" hole added to the 3" TB which is much different then the expanded 12 square inch volume by the time it reaches the injectors and goes into the engine

I don't think we are disputing it has "some" effect, at least I am not, but what I am disputing is the degree to what these effects are and how they may or may not make any noticeable difference in engine life, wear, or longevity other then in theory on paper.

I wont dispute this but will say I have nothing to suggest the difference is anything other then negligible and unmeasurable

there is no real life documented proof of this and quite to the contrary, people who have removed or blocked off the EGR over the last 25 or so years have reported little to no difference in engine temps and if any change at all they report better performance from improved combustion.

again, there is no real life documented proof of this and quite to the contrary, people who have removed or blocked off the EGR over the last 25 or so years have reported little to no difference in engine temps and if any change at all they report better performance from improved combustion.

that said im sure there is "some" difference and if we are talking about the difference in the engine lasting 700k miles or 750k miles then after that many miles or likely even needing to be more then that, it may come into play as something you can measure but I think we are talking about things that would take that many miles to show up.

 

it is strictly there for emissions, not to increase the performance or life of an engine. A cool dense air charge is going to give you your best performance, hence why we put intercoolers/after coolers on after a supercharger or turbo, to cool the air charge back down that has been heated from being compressed to prevent heated aircharges from causing pre-ignition . So I don't see how dumping hot dirty gasses into your cool intake air is helping anything as far as longevity/performance, other than maybe the fact the warm gasses will richen the fuel air mix a bit maybe preventing a possible lean condition but doubt it.

that being said vehicles now days are designed with the egr system in mind and its not just an after thought slapped on to please the EPA like back in the day so as people have mentioned there's not alot of gain to be had by blocking/removing it on modern gas vehicles. Diesels is another story and it was just stupid that they had to put egr valves on diesels. The soot from a diesel is alot thicker and grittier and should not be ran back through the engine. Its nasty stuff especially when the soot from the exhaust gets mixed together with the oil vapor from the closed pcv system, it makes a nasty tar that is a whore to try and clean out.

 

keakar, you started a thread titled EGR-to delete or not delete. I've provided multiple sources on the matter. If you have your mind made up about it go right ahead.

 

that question was answered earlier in the thread, then the conversation continued into what the results of removing it would be.

thank you for your contributions to the thread, but no need to get testy just because I made good points about what that could be on paper vs what the real world results of removing it might be. I am glad you provided the details you did and it is important to not dismiss or ignore that info but it does need to be taken in the proper context so it is not presented in a misleading manner to imply certain engine damage, which will not happen.

if your claims of engine damage because of removing it would be true, then there would be people posting about engine failures after deleting the EGR on their engines. my only disagreement with what you said was what the one or two degrees hotter the engine runs without the EGR valve in operation would have any "real world" measurable effects on engine wear and life.

no one I think, certainly not me, are trying to suggest there is "no" difference in running with it or without it, all im saying is I can find nothing and have seen nothing to suggest even remotely it has ever done "any" harm to any engine where you remove it.

none of "this" question is related to the decision weather you should or should not remove it, but it only speaks to the possible results of what happens if you do remove it.

 

It seems like if it is working and not throwing a code it would be a waste of time to remove it. No one seems to cite an increase in performance (on a non boosted engine) when it is removed and it performs a peace of mind function (even if not necessary) when it is working properly (cooler cyl temps and EGTs). What more do you want? I doubt someone would be able to pinpoint their catastrophic engine failure directly to the removal or inclusion of their EGR system.

It is much like the smog pumps on newer cars, entirely benign until it breaks.

 

Like I said, if you're mind is made up, go right ahead.