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.

 

[Puller]

yeah, thanks. that's the way it's going to be regardless. I just wanted to add some food for thought to help those who may have not had a firm belief in either direction.

 

[tstkl]

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.

you seem to use the plural form of a lot of words here, mind improvising on what the other free mods are that do more harm then help?

 

[Puller]

It only works under light throttle. It's vacuum is from ported vacuum.

 

[MyBeatGSX]

"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."

"It only works under light throttle. It's vacuum is from ported vacuum."

I know my saturn had an electronic EGR that was opened whenever the ecu felt it needed to be opened. I'm having a hard time getting used to this DSM with everything vacuum controlled.

I'll be interested in this possible exhaust size/cat debate. As for MAF hacking, I agree with that being stupid.

 

[jaredgsx]

"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."

"It only works under light throttle. It's vacuum is from ported vacuum."

I know my saturn had an electronic EGR that was opened whenever the ecu felt it needed to be opened. I'm having a hard time getting used to this DSM with everything vacuum controlled.

I'll be interested in this possible exhaust size/cat debate. As for MAF hacking, I agree with that being stupid.

you think hacking the maf is stupid?

 

[MyBeatGSX]

Yea, if you need more flow get a GM MAF and do it the right way. If you're hitting fuel cut, then fix the problem, don't bandaid it. I'm not a fan of lying to the ECU when there's a better and equally practical way to do it. I'm sure I'll take lots of flack for that opinion, but why do you need get into compensations for the compensations for the compensations that are compensating for your hacks. Its all just becomes multiple layers of mess and inaccurate information to the ECU.

 

[jaredgsx]

Yea, if you need more flow get a GM MAF and it the right way. If you're hitting fuel cut, then fix the problem, don't bandaid it. I'm not a fan of lying to the ECU when there's a better and equally practical way to do it.

i did it to get rid of my fuel cut and it worked..took me like 15min and i cost nothing. I am saving for the maft setup but i did not have 230ish sitting around.

 

[Puller]

I entirely agree with MyBeatGSX. If you don't have the money, don't bother in my opinion.

 

[jaredgsx]

There are many ways to solve a problem, for me this worked. If i was the kind of person who cared what other people thought i would have asked before i did it, but i'm not. Hacking the mas if an easy fix for a problem when running close to stock boost and hitting fuel cut...since i want to up my boost and i know that a hacked mas can not handle it, i will get a gm maf and lie to me ECU another way

 

[99gst_racer]

One more thing I can add is it's original intention was in fact to combat knock.

Not that I doubt you, but may I see your proof of this? I'm sure one of the Mitsu. engineers from the late eighties documented this if it is true. I'm just wondering if you are getting the above information from an undisputed source or from the mechanic next door.

 

[mgcook]

here are some links, whether they are credible or not I have no idea. but they are still a good read and offer some insight into the EGR system.

http://www.ukcar.com/features/tech/Engine/techno/exgr.htm

http://www.highperformancepontiac.com/tech/pon_0509_1973_emissions/

 

[drivemusicnow]

If you look at basic design concept of the EGR valve, like "Puller" said, it displaces air. What this does is effectively LOWER the overall displacement of the engine. Yes, it makes your nice shiny manifold dirty. Yes, extremely low throttle will notice slightly less power, HOWEVER, the benefit is when coasting, letting off of the throttle, your 2.0l engine is only actually displacing 1.8l. (the rest has been explained well above)

As for the chicken and the egg... I can tell you that Mitsu engineers are not the first to apply the EGR valve. In fact, its been around for awhile (1972 http://www.misterfixit.com/egrvalve.htm). I would expect the reduced combustion chamber temps was the goal, with both things in mind.



As for the Catalytic converter topic. I disagree. I think on a turbo car there is an extremely good reason for getting rid of it. People who are environmentally friendly argue that car smog is too much of a problem. First thats BS. Second, the manufacturing smog that is created trying to manufacture all the new parts required to cut down on emmisions would be an interesting comparison.

Heres the logic. A turbo works through energy transfer. Pressure drop from the exhaust mani to the downpipe, and temp drop between the two creates kinetic energy. Heres the key. By adding a cat, you effectively raise the pressure in the downpipe. This creates LESS of a pressure drop, which thusly creates less energy.

People will argue that if you look at the dyno numbers, you typically lose less than 10 horspower. These same people don't know how to READ a dyno graph, nor do the see the differences between under the curve power, or spool up characteristics.

Cats do absolutely nothing for you other than the emmissions purpose they serve.

I think the MAF hacking is a dangerous but effective way to tune the car. Think of it this way, if you can control the amount of unmetered air that goes into the engine, You can effectively tune the car to a given A/F ratio. Yes its tricking the ECU, but so is every possible tuning anything other than possibly DSMlink, a chip, and a standalone.

I will note that if you don't know what you're doing, and cut out the entire lower part while not increasing or at LEAST monitoring the fuel/air fuel ratios.. then you're dumb, but you'll find that out later when you're picking out metal shavings from your oil pan.

 

[oztofrdm]

All i have to say is that i have mine taken off. Nothing changed when i took it off except a cleaner engine bay and less chance of a boost leak thats enough to me I still get over 20mph city and 30mph highway as long as im not boosting all the time anyways. If your really getting knock because you took the EGR off your doing something wrong.

 

[Defiant]

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.

When was the last time you saw a race car being driven down a highway at 1/16 throttle because of a speed limit? The "race car" card doesn't play on the street. Racing slicks work a helluva lot better than street tires, too... if you have someplace handy to swap them off when the clouds sprinkle.

I've been trying to tell people to leave their EGRs alone for years. You see what kind of shitstorm it creates.

You all do what you want with your cars, according to what you "know" is best. And I'll do the same.

 

[92showeclipse]

ok i dont mean to be an asshole about anything i say but first and formost let me just say that pulling egr in my opinion is a good thing unless YOu live in a state that regulates it on a regular basis, second of all "Puller" if removing the egr is so bad and can harm a dsm so much then why have i not had anything but good with my 95 tsi since i romved it all.....it has made my car run alot better and a crap load faster......and considering the fact that u have a 90 awd and ran a 14.3 in my book is pretty pathetic considering the fact that my 95 fwd tsi ran a 14.5 at the same mph as ## dsm did with only a 2.5 inch test pipe back exhaust,shitty ass tires and 90 degree track temp.......bwahahahahaha...........but that is only my 2 pennies worth

 

[Puller]

That's what I ran, bone stock, without "free mods". The engine underwent an overhaul and it was sold. I havent had that car for a year and a half. I just haven't updated it. My faux pas. Seeing how you, '92showeclipse' have had no problems as a result, judging by your attitude, i'm willing to bet your car rarely sees the amount of throttle required to utilize an EGR, thus making you a well suited person for that modification. Someone had mentioned their saturn not having vacuum to the EGR. Some manufacturers use a stepper motor with a sensor to control EGR position. (As you described)

 

[99gst_racer]

As for the chicken and the egg... I can tell you that Mitsu engineers are not the first to apply the EGR valve. In fact, its been around for awhile (1972 http://www.misterfixit.com/egrvalve.htm). I would expect the reduced combustion chamber temps was the goal, with both things in mind.

That link contradicts itself.

For example, this second sentence of the first paragraph, "Way back in 1972 GM used them in an attempt to reduce emissions of oxides of nitrogen (NOx) which were a major cause of air pollution."
That clearly states what their original intentions were with the EGR.

And then further down: "The automotive engineers figured that they needed to do something to lower the peak combustion temperatures....... So they invented a way to allow some very inert gas to get back into the combustion chamber only when needed."
And now it states that it is for reducing combustion temp and knock.

So which is it?? I understand that Mitsu. wasn't the first to use the EGR valve, but I am curious to know if they chose to use it mainly for emissions or knock control.

 

[drivemusicnow]

That link contradicts itself.

For example, this second sentence of the first paragraph, "Way back in 1972 GM used them in an attempt to reduce emissions of oxides of nitrogen (NOx) which were a major cause of air pollution."
That clearly states what their original intentions were with the EGR.

And then further down: "The automotive engineers figured that they needed to do something to lower the peak combustion temperatures....... So they invented a way to allow some very inert gas to get back into the combustion chamber only when needed."
And now it states that it is for reducing combustion temp and knock.

So which is it?? I understand that Mitsu. wasn't the first to use the EGR valve, but I am curious to know if they chose to use it mainly for emissions or knock control.

You're forgetting that all those effects are caused by the same thing. Lower combustion temps gives you less NOx.

And yes, Mitsu used it primarily for emmissions.


Oh, and as far as "dirtying" things up... PCV VALVE!!!!!! seriously, nothing like spraying oil, blow bye, and hot air into the intake tract to REALLY get things messy.

 

[dsm-onster]

So which is it?? I understand that Mitsu. wasn't the first to use the EGR valve, but I am curious to know if they chose to use it mainly for emissions or knock control.

Maybe they did it because Federal mandate requires an egr. Isn't there a federal law requiring all pasenger, truck, public, etc. vehicles to be built with an egr from the factory?

this makes me think of the 70s when the Federal Powers made every manufacturer go to 10 mph bumpers from the 3 mph bumpers... I don't think i could get in an accident at 10 mph... If I did, I would be slow and unfit to drive on public streets .

My point is, I think it is a Federal requirement to install an EGR Valve at the plant. And the government can force regulation even if it does not work at all (i'm not saying egr valves don't work). If the government thinks it works they can make it law.

P.S. My cams would fail me even with an EGR... Black soot in my intake would make performance worse. It was a free mod that I did after I got these cams.

 

[LandoAWD]

ok i dont mean to be an asshole about anything i say but first and formost let me just say that pulling egr in my opinion is a good thing unless u live in a state that regulates it on a regular basis, second of all "Puller" if removing the egr is so bad and can harm a dsm so much then why have i not had anything but good with my 95 tsi since i romved it all.....it has made my car run alot better and a crap load faster......and considering the fact that u have a 90 awd and ran a 14.3 in my book is pretty pathetic considering the fact that my 95 fwd tsi ran a 14.5 at the same mph as ## dsm did with only a 2.5 inch test pipe back exhaust,shitty ass tires and 90 degree track temp.......bwahahahahaha...........but that is only my 2 pennies worth

Shut it. Read the rules.

I entirely agree with MyBeatGSX. If you don't have the money, don't bother in my opinion.

Tell that to Al Blaha.

 

[99gst_racer]

Maybe they did it because Federal mandate requires an egr. Isn't there a federal law requiring all pasenger, truck, public, etc. vehicles to be built with an egr from the factory?

My point is, I think it is a Federal requirement to install an EGR Valve at the plant. And the government can force regulation even if it does not work at all (i'm not saying egr valves don't work). If the government thinks it works they can make it law.

If this is true, then the intended purpose of the EGR is for emissions, not knock control. That mean Puller's statement is incorrect:

One more thing I can add is it's original intention was in fact to combat knock.

And yes, Mitsu used it primarily for emmissions.

You got proof of that? Apparently nobody does..... Some say it's for emissions (you, me, etc..) and some say it's for knock control (puller). I have yet to see proof from Mitsu for either.

Oh, and as far as "dirtying" things up... PCV VALVE!!!!!! seriously, nothing like spraying oil, blow bye, and hot air into the intake tract to REALLY get things messy.

I already eliminated that too. I have my PCV line ran into a vented catch can.

 

[xveganxcowboyx]

If this is true, then the intended purpose of the EGR is for emissions, not knock control. That mean Puller's statement is incorrect:

I think this makes perfect sense. The article clearly states it was used to reduce NOx. You do this by reducing combustion temps (it only forms after a certain temperature point). The fact that it was introduced in 1972 just adds to that argument. That was when emissions regulation came into full practice.


To whoever was talking about mandating the use of EGR valves, there would be no point. It helps emissions IF and ONLY IF your car runs hot enough to produce large amounts of NOx. I believe this is why N/T DSM's didn't have them (someone correct me if I'm wrong here). There are plenty of ways to control combustion temps and overall emissions. The way the law is structured, as long as the manufacturer meets the basic requirements, the types of technologies don't matter much. If EGR's were mandated, it would discourage development of new and potentially better tecnologies.

 

[wolf20043]

I think this makes perfect sense. The article clearly states it was used to reduce NOx. You do this by reducing combustion temps (it only forms after a certain temperature point). The fact that it was introduced in 1972 just adds to that argument. That was when emissions regulation came into full practice.


To whoever was talking about mandating the use of EGR valves, there would be no point. It helps emissions IF and ONLY IF your car runs hot enough to produce large amounts of NOx. I believe this is why N/T DSM's didn't have them (someone correct me if I'm wrong here). There are plenty of ways to control combustion temps and overall emissions. The way the law is structured, as long as the manufacturer meets the basic requirements, the types of technologies don't matter much. If EGR's were mandated, it would discourage development of new and potentially better tecnologies.

The N/T's did have them
(at least all the ones I have worked on have)
Mike

 

[dsm-onster]

The N/T's did have them
(at least all the ones I have worked on have)
Mike

Yea. My ol' 92 n/t had an egr valve. I blocked it with a plate... for spite. At the time, i was heavily into Black Flag . Seriously, it helped me keep from cleaning out my TB to stop the damn rpm "breathing" issue.

 

[xveganxcowboyx]

The N/T's did have them
(at least all the ones I have worked on have)
Mike

Thought I had heard they didn't. Thanks for the correction.