EGR Blockoff Discussion [Merged 8-8]

[Puller]

Before I speak my piece, this is directed to 'tuners' who are some what new and are somewhat impressionable. However there are many of you that never learned certain things the correct way. This also applies to stock or nearly stock vehicles. That said: Although many DSM followers are on the forums to help and provide insight, many fail to understand how or why certain components operate in the way they do. Even on this site's 'tech articles' there are modifications which do far more harm than good. I'm only going to refer to the articles posted in the free mods of this sites tech articles. First i'll start with the EGR block off. Whomever wrote this deposition clearly had no idea what they were talking about. The purpose of an EGR valve is to recirculate exhaust gas into the intake, as many know. What people fail to realize is that the EGR valve was designed to combat knock. Exhaust gases, on a normal running engine, are inert. They are recirculated to COOL combustion chambers by displacing usable air with inert air. Coincidentally that acts as an emissions device by lowering NOX (which is a product of heat). NOX is the EPA's main concern as far as emissions. Another point, it's operative under light cruise, not under heavy accel or WOT because it's vacuum is from ported vacuum. So that doesn't even bother most DSM drivers ;-) So if you blocked off your EGR i have only a couple things to say: congratulations you just increased the likelyhood of knock and the emission of NOX. Also you just found a quick way to fail an emissions test. If people would stop and think, they'd realize they aren't as smart as the Mitsu engineers and the thousands if not millions of dollars of R&D that went into that "stupid emissions device". Another note: under WOT emissions isn't a concern. You're vehicle goes into open loop and runs rich. a rich mixture emits HC into the exhaust. therefor most emissions devices are disregarded during WOT including your O2 sensor.

 

[JohnnyC]

Anymore helpful info? You do realize that those 'free mods' were thought of by people who are probably more knowledgeable than you, and if they were very harmful, people wouldn't have been doing them for the past 14 + years.

BTW, the tech guide does also state, "This will also make your car illegal in the eyes of the emissions testing facilities."

 

[Puller]

I'm not going to play the who's smarter than who game. What i said was objective, and factual. I understand they acknowledged failing emissions. good job. it's a pointless modification. a working egr helps your car under normal circumstances, and doesn't hurt it when there's a demand for HP. Until an engineer can debate me in this topic i don't care who has been blocking it off for how many years. that doesn't make it right or useful.

 

[keymaster]

So explain this then...If the EGR doesn't function under WOT, how is it helping combat knock? Haven't heard of too many people knocking during light cruise.

 

[CanadianTSi]

I agree with you, I see no reason to remove it since it isn't active under WOT.

 

[wolf20043]

The free mods tech articles are there for anyone who wants to do them. The ones who want to for whatever reason will, while others wont for reasons of their own. Maybe this thread will help someones decision on whether to do it or not, who knows.
Mike

 

[Puller]

under light cruise, you're car is concerned with fuel economy and emissions since this is what most sane people drive daily. you are running as lean as possible in order to extend fuel economy. as we know, lean conditions are hotter, which in turn creates preignition, which we know is bad. adding inert gases from the exhaust cools and combats knock. instead of dumping more fuel in and hurting economy, these inert gases are added.

 

[ilikespeeding]

Accutally the EGR is designed to put extra nitrogen into the combustion chambers which controls burning...what percentage of nitrogen is in air? 74%. How about exhaust? I havent been able to figure that out...but I can assume that 74% is alot. I dont think I would put a filter on the EGR like Ive seen before...cause that would cause you to burn hot unmetered air and I dont think Id fill it either, but I cant say that it would hurt the car unless something else was wrong. But what do I know?

 

[Puller]

take this information as you want. for those of you who see my point and have a working comprehension of my point instead of just blurting out the first thing that comes to mind, it is appreciated. even if you disagree, if you have an intelligable point i'll actually acknowledge it instead of rambling about how many years i've been doing this or saying my dad can beat up your dad etc. i'll also add that my information, isnt' from synthesized from my own knoggin'. this is part of the curriculum of a very reputable school. it was also presented to me by master technicians whom have worked in the field longer than my life spans. this includes a chrysler and mistubishi master-techs, several GM techs, honda techs etc. so it's not just another do it yourselfer rambling asinine info. im trying to help, not provoke.

 

[Puller]

actually nitrogen isn't the point of an EGR valve. the primary exhaust gases we are concerned with are: HydroCarbon, NOx, O2, CO, and CO2. nitrogen combined with oxygen under high heat is the most harmful emission known as NOx or Oxides of Nitrogen. the EPA and fed's would never enable this by making a device that encourages this. Exhaust gas is inert. you can't reburn a 14.7:1 exhaust gas. it doesn't combust. it displaces oxygen as to cool cylinders, and reduce knock without adding fuel.as far as a filter on the egr...i haven't seen that but i can assure you that's a stupid modifcation as well.

 

[98RedGs]

Not saying your wrong at all. But, the modifications were thought up by others that have done them and seen positive/neutral effects but no negative effects.


I honestly think your post are well written but you need to remember one thing.
The SHIFT key is used to raise the size of a letter at the beginning of your sentence.
Don't think that because you use other punctuation marks you can ignore the use of proper capitalization.


Thank you,
John



p.s. I'll point out your theories to some of the moderators/wisemen and see what they think and hopefully the conversation can stay civil.

 

[MyBeatGSX]

This topic was beaten to DEATH on turbosaturns.net a few years ago (yea I used to drive a saturn). If people can get a pos Saturn to put 330hp to the wheels reliably, I think they know what they're talking about.

The general concensus of 90% of the board members (including master techs and GM engineers) can be sumed up in a few points:

#1. EGR DOES HURT part throttle performance. It lowers combustion temps by contaminating the mixture with nonuseable exhaust gas. That means a less efficient burn, less power, poor gas mileage, etc. This is exactly the reason its disabled at wot.

#2. EGR DOES NOT effect wot performance. This is the main reason people argue against blocking it off.

#3. It DOES dirty the intake tract, increases fouling of colder plugs, dirties the injectors, combustion chambers, etc. This is the main reason it should be blocked.

#4. The knock reduction ablities are limited. It does decrease combution temps which reduces knock, but it also polutes the mixture which increases knock. How often do you get light load knock anyway? Again, its nonfunctional at wot so its not doing any good for knock reduction anyway.

#5. There are NO long term bad effects of blocking it off. In fact you'll keep everything much cleaner. Its sole purpose is for emissions reduction.

If in doubt, just ask yourself... when was the last time you saw a race car running with an EGR? When was the last time you saw a highly tuned car running with an EGR? I don't remember either. There's a reason for that.

For the record. My EGR is blocked off and my car failed the computer test (not egr related) and was then kicked to an old style sniffer test which it passed with flying colors.

 

[wolf20043]

The free mods tech articles are there for anyone who wants to do them. The ones who want to for whatever reason will, while others wont for reasons of their own. Maybe this thread will help someones decision on whether to do it or not, who knows.
Mike

As I said there^^^. I am not for it or against it, simply neutral in what others do with their own car. Personally we have absolutely no emissions in Pueblo so I eliminated mine for the purpose of simply cleaning a lot of crap out of My engine bay (plenty of room now that the motor is out ). But every car I rebuild to re-sell has the EGR functioning because(as I said) it is not My business to make that choice for anyone else. But I do completely understand Your post, and it adds an objectionable opinion to those who are not sure if they want to do it or not.
Mike

 

[xveganxcowboyx]

Well, I generally oppose anything that increases emissions drastically, especially if there is no major performance gain. I don't see much point in blocking off the EGR. I think it's mostly a 'feel good' mod in the sense that performance enthusiasts generally believe emissions devices hinder performance.

That said, I do have my EGR blocked. I broke a t-fitting on some vacuum lines and it was much easier to block my EGR off and rip out some lines than repair or replace the piece. I've had it this way for a while and have seen no noticeable difference. I haven't been logging so i can't say anything about knock other than I haven't felt timing being pulled drastically.

The dirty engine issue is kind of stupid. You can just as easily clean out the engine occasionally as block off the EGR.

I guess I just think, if it ain't broke, don't fix it. If it starts to malfunction, screw it. As far as emissions go, I think the bigger battle is getting people to keep cats on their cars.

 

[Puller]

"#1. EGR DOES HURT part throttle performance. It lowers combustion temps by contaminating the mixture with nonuseable exhaust gas. That means a less efficient burn, less power, poor gas mileage, etc. This is exactly the reason its disabled at wot."

You're half right. It is a less efficient burn, which is less power. It doesn't hurt fuel economy what-so-ever. It allows the car to run on a lean threshold for fuel economy. Near the lean threshold you start developing knock (we all know). By adding a gas that consumes space without result enables us to continue to use less fuel which obviously enhances economy. There are 3 ways to combat knock: retard timing, add fuel or subtract air. It's just utilizing the latter. Also the reason it is disabled at WOT isn't for any of the reasons you insisted. It runs off of ported vacuum because at that throttle position is when we are concerned with mpg and emissions and knock the most. WOT we are not. We run rich which because of a high demand for power, no concern for fuel economy. Knock is handled by the rich mixture.

"If in doubt, just ask yourself... when was the last time you saw a race car running with an EGR? When was the last time you saw a highly tuned car running with an EGR? I don't remember either. There's a reason for that."

The reason for this is because race cars and highly tuned cars, are NOT concerned with fuel economy, part throttle, or emissions for that matter. Richening the mixture takes care of the knock and the risk of NOx. An EGR helps driveablilty and all that it encompasses. It provides as a means of lowering knock while savoring fuel economy.

 

[Puller]

Also note my intentional use of the SHIFT key. Haha. Sorry about that.

xveganxcowboyx i completely agree. I don't have time or energy to explain the other misconceptions such as cats. All that I can say is the amount of restriction they provide, is not nearly capable of justifying the removal or hacking. Tuners have beaten into their heads that back pressure is bad when it actuality it isn't, to an extent. But aside from that i'll leave you with, it's your car, i'm just trying to help. If it's a race car, piss on the EGR. If it's a daily driver, think about it before you deside to block it off. Daily driver guys remember, how much does it cost a manufacturer for an EGR valve. Let's take 5 dollars. Multiply 5 dollars times a million cars produced. Do you think they are going to spend the additional 5 million dollars for this device if they don't have to? Not a chance. Budget is a big deal. If they can use 20 gauge wire instead of 18, you better believe they'll do it to save 3 pennies per car. Please note, also their are other ways manufacturers are dealing with the things EGR handles. GM uses a phaser i.e. the trailblazer straight 6, some companies use valve duration, overlap and timing to do it. EGR is going to be on the way side because of new techniques. But if you're car has it, it's for a reason.

 

[99gst_racer]

Puller - Thank you for posting your information in a professional manner, but this has all been extensively covered in previous threads. There has always been the big debate: decreasing knock using the EGR VS. gaining HP by not using the EGR because it displaces oxygen.

I do agree that I wouldn't consider this a free performance mod and recommend the procedure to every DSM that walks (no pun intended) the earth. however, I also wouldn't consider removing it or blocking it off to be a horrible sin.

I am currently running my EGR blocked off for one good reason: When my EGR failed, the price of a block off plate was much more appealing than the price of a new valve. That is the only reason I did it.

The main purpose of the exhaust gas recirculation valve is for emissions purposes (like you already explained). The fact that is displaces oxygen (the opposing function of a turbocharger) and it cools cylinder temps, is just an added bonus. I don't feel that it's original intended purpose was to combat knock, but not being one of the original designing engineers, I can't be 100% sure. Also, I have never seen irefutable proof that it actually makes a real life difference in knock counts. I've only read and seen theory. And most stock cars don't have to work about combating knock anyway, as they run a factory rich tune.

As far as gaining horsepower with it removed, I don't buy that either. The gains (if any) from not displacing such a small amount of oxygen would be too small to notice, count, or even record.

I would also recommend not removing it unless you are building an engine that is more performance oriented than daily driven or unless it fails. I think most people are smart enough to know that removing emissions equipment will cause them to fail the emissions testing. And remember, not all Engineers are perfect. That's why we have crankwalk, nationwide recalls, etc......

Please keep this a professional debate though. I don't want to see it turn into a pissing match with handfuls of misinformation flying back and forth.

 

[MyBeatGSX]

I agree with you about the increased gas mileage and I argued the same point on turbosaturns.net but the majority of people seemed to disagree. But either way, decreasing power is the side effect. IMO a car running 7.8:1 compression needs all the part throttle power it can get. I can tell you from personal experience on my saturn that the part throttle gain in a low powered car is noticable as is the loss of fuel mileage.

The dirtying issue is debatable. But it IS not debatable that it DOES dirty the intake tract. Even the EGR supporters will admit that (and again I'm talking from personal experience as well). And cleaning it is not as easy as spraying carb cleaner in the TB. And really, do you want all those deposits going through the turbine when you do decide to clean it out?

And yes I do agree with the above person that there is no worth while performance gains to be had. If you want more power then push the pedal in further. The purpose of removing it is to keep things clean.

 

[Puller]

Professional and civil by all means sir. One more thing I can add is it's original intention was in fact to combat knock. Back in the dinosaur days, there was no way to retard timing. It was mechanical and at certain RPMs and engine loads, knock was existant because timing was incorrectly advanced. We all know too far advance at the wrong time causes preignition. So they developed the wonderful at hand: EGR valve to displace the O2. Back then they didn't even care about emissions. Anyhow, I want to thank all those who contributed and challeneged. I'm here to help for all whom care.

 

[GreenGSX]

My cyclone intake has no provision for an EGR valve. I wonder what those Japanese engineers where thinking? When I put the Cyclone on the car there was no change in either the mpg or part throttle knock. Running an EGR or not, in my opinion, only really makes a difference to Uncle Sam.

 

[Puller]

You're probably right. I believe it has developed into the opposite of it's original intentions. It was for knock on an inappropriate ignition advance, now it's more for NOX and helps with knock which ill agree is minimal. Nice debate guys.

 

[MyBeatGSX]

Professional and civil by all means sir. One more thing I can add is it's original intention was in fact to combat knock. Back in the dinosaur days, there was no way to retard timing. It was mechanical and at certain RPMs and engine loads, knock was existant because timing was incorrectly advanced. We all know too far advance at the wrong time causes preignition. So they developed the wonderful at hand: EGR valve to displace the O2. Back then they didn't even care about emissions. Anyhow, I want to thank all those who contributed and challeneged. I'm here to help for all whom care.

That sounds like you're leaving the topic. While we got a topic with this title, lets discuss it all. If everyone can continue to keep it civil it will benefit everyone especially automotive newbs, regardless of what side people take.

So what other problematic free mods do you see? The cat delete was mentioned if I remember correctly.

 

[Puller]

Maybe another day, i'm exhausted (no pun intended ) from work all day, I just wanted to shed a little bit of light. When I have some more time/energy i'll bring up some other dead horses so we can beat them some more. Cats, MAF's, Exhaust size, and whatever you guys have to add.

 

[RoasT BeeF]

How about this.

If you think its going to reduce knock and cause more harm than good, leave it in. The rest of us will take it out.

Thanks for sharing though.

 

[tstkl]

Also note my intentional use of the SHIFT key. Haha. Sorry about that.

xveganxcowboyx i completely agree.

Your second word of your first sentence after your appology for not capitalizing should be capitalized. Not that I care, since the only word on my keyboard that you can read is "Shift".

I read somewhere that the egr valve is actually activated when you are taking your foot off of the gas, I dont know if there is any truth to this, but I just though I would put it out there.

Personally, I have my egr valve blocked off, but I believe that my reasoning is quite reasonable, smog techs take bribes, my car passed with flying colors before I blocked it off. Theres all this carbon around the egr tract and valve, which I dont want in my intake, and most importantly, the smim I bought doesnt have a place for one, and Im not about to give a rats ass.