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

I agree as I stated much earlier in the thread before the discussion turned to the topic of what impact "if any" would result from removing it and this is where I disagree with Jbecker's claims that it will harm the engine to remove or disable it.

once again, I agree in principle (but in truth many with regular non performance engines that have removed it "claim" better performance), the fact that I do agree with you that it will have no measurable change in performance serves to prove it makes so little difference in how the engine runs that it cannot have any real impact on the engines wear patterns or life expectancy even if it does run a degree or two hotter.

what are you talking about, "what more do I want?", I am in agreement with this, what I dispute is Jbecker's claims that it will harm the engine to remove or disable it, that is all.

and again I agree with you completely.

the only thing my mind is made up on is that having the EGR or not having it makes zero difference in the engines life span until you get over 500k miles or 30 years into its lifespan.

beyond that only point in which I don't agree with you, I agree with your other points about keeping the EGR but "if you're mind is made up, go right ahead and ignore that"

 

I actually never stated that. I only quoted links from other sources saying engine damage was possible. And people have certainly burned up exhaust valves from lean running conditions.

 

yes they have, and they have burned holes in pistons and melted spark plugs but removing the EGR doesn't make enough difference to change a lean or rich condition, its only like 0.5% of the entire volume of gas being used.

I appreciate your input, I just don't want to encourage wrong ideas to be believed so in that interest I wanted to be sure to point out the one wrong assumption made in the details you were quoting. I don't disagree with anything else in the details you quoted but the engine damage part.

I am sorry if I wrongly attributed those comments to you.

 

What happens when you remove some pure oxygen from combustion but keep the same amount of fuel? A richer mixture. That's what the system does. Where the EGR works is reducing fuel consumption while maintaining an adequate fuel to air ratio.

Now remove the EGR, trick the computer to thinking it's still there with a resistor, and you introduce more oxygen into the system creating a leaner mixture. You also run into problems with timing and relying on the knock sensor to keep detonation down.

Like I've said from my first post here, removing the EGR and using a resistor to trick the computer from throwing a code isn't the answer. You need to reprogram the computer for fuel air mixture and retard timing in order for it to be ideal again.

But at this point I'm talking in circles it seems.

 

First gens are still OBD-II. And you won't know for sure unless you strapped it on a dyno with a sniffer in the tail pipe and measured the air fuel readings under a load throughout the rpm range.

 

ok, so your point is, the lean condition isn't caused by the EGR delete but the resulting rich condition caused by the EGR delete, in your opinion or the opinion your data is based on, the EGR delete causes the ECM to lean it out too much in an attempt to compensate for the now richer o2 sensor readings.

that point of view is understandable to assume but everything I know says that it only will restore it back to the original fuel air mixture ratio you had with the working EGR rather then making it leaner without the EGR. and equally if the opposite were true and o2 was reading leaner, then the ECM would just add more gas to bring things back to where they belong.

the ECM will always adjust the timing and fuel air ratios to where they need to be no matter what.

at least this has been a very god discussion and many people will learn a lot from reading the thread.

I thank everyone for their contributions to it, all comments have been very helpful

 

No. With the EGR in place and when it is functioning, the recirculated gasses decrease the amount of air entering the combustion chamber. Remember there is only so much you will get in when the intake valves are open. So because you have less oxygen in there now due to a partial charge of recirculated exhaust gasses, it takes less fuel to combust properly. When that system is removed you still get your normal fuel charge, but there is now more clean air than before, this is what causes the lean condition I am talking about, as well as the other sources I provided.

And again, no, the computer will not always adjust to compensate. Many naturally aspirated vehicles will require a tune with minor bolt on changes. Sometimes even an intake alone is enough to push the air fuel ratio to a leaner condition. This is why many who do an intake and a cat back exhaust will have the computer reflashed to regain the normal parameters. They aren't trying to get more power, they are just trying to get the fueling correct.

 

ok, I see what you are saying now.

I have read though, in my attempts to cure rough idle issues through tuning, that our first gen ECMs cant be tuned because they are just too basic of a computer since the technology they were created with is old and very limited in what you can do with it.

perhaps if a newer more modern chip were capable of being installed in it, then that could change the limitations of what you could do with it.

 

I'm not sure what's out their for first gens, even though I had a 99 Tacoma TRD and 00 4Runner both with the 3.4. But about 12 years ago I had a 97 VW Jetta VR6 and I got a chip for that. Rather than a reflash I had to open the computer up, remove one of the small chips inside, and replace it with a new one. It bumped up the fuel curves and raised redline. So maybe there is something like that available for first gens.

And it wasn't one of those things you see on eBay. It was made by a local tuning shop that specialized in VW and Audi.

 

Hmmm, marinade on this then. If I put a cold air intake with a high flow air filter on I'm creating a better, cooler, denser air flow. Thusly introducing more air into the combustion chamber. But, this is pre MAF. So the ECU accounts for this as it sees it on the MAF sensor. Agree?

Deleting the EGR system and tricking the ECU with a resistor takes away from the volume of non fuel into the combustion chamber. Even though it's hot gases, it's a know variable to the ECU. Even though it's mostly non combustible, this is where the lean fuel mix comes into play. Agree?

So, if you were to tie the EGR port into the air box pre MAF then the ECU would still think it's gases of a known variable. Although it's now a combustible o2 rich 'gas.' This should, in theory, also cause a lean burn due to more o2 being introduced. But you still need a functioning EGR system to do this and the cold air would now throw a CEL. Agree?

So the only true and correct way to remove the EGR system would be to somehow write the EGR equation out of the ECU. Agree?



But I'll say this. Should my EGR fail or throw the first code for it, I'll be putting a resistor in and blocking the port. I almost did it when I put on my header, but the Google search I did that day said the same as the general consensus in this thread...in not near as many words. If it ain't broke, don't delete it.

 

Pretty much, you seem like the kind of guy that would argue with a wall..

 

Most likely the only way to eliminate the part of the computer that regulates the EGR part of the fueling process would be to run a stand alone management system. But you can just tune it out by increasing fueling in that range. Assuming you have a computer capable of that.

I merely provided facts and data on how it works and the drawbacks of removing it. Feel free to take that information any way you want.

 

I apologize if I sounded disrespectful in my previous post. I am pretty sensitive to all the hate for emissions standards equipment on vehicles since they exist to protect the very people that complain about them. We've come a long way over the last several decades with regard to smog laden cities, lead compounds in the air, acid rain, NOx poisons, carbon particulates, ozone levels hanging near the ground, hydrocarbons, etc.. The air is many times cleaner than it used to be since the Clean Air Act, which is pretty impressive considering the US population has grown by over 100 million and there are many, many more vehicles on the road than there were in 1970.

Now that that's said, you have been provided with statements "on paper" that are indeed measurable, and very likely would not have been stated without proof. But you have not provided any outside sources to support your own counterpoints. Not saying that you're not correct, but I'd like to see what drives your thought processes outside your theories regarding hose diameters, or what one or two people have posted in an online forum. It would probably help to put a lot of peoples' arguments to rest in this thread.

 

hose diameters:

the throttle body inside diameter - well it uses a 3"rubber boot so I called it 3" in size

the EGR tube - well I used a 10mm bore cleaning brush from my gun cleaning kit and it was a very tight fit but I called it 3/8" diameter tube which was being generous at best. the actual EGR valve itself has an opening smaller then that and the smallest choke point determines just how much can actually pass through that part of the system.

I think I have been very accurate in my size estimates but I did not break out the calipers to check exact measurements as generalities were more than enough and if anything I overestimated the flow you get from the EGR.

as to the rest, thousands of people have deleted the EGR in their vehicles and there are no widespread documented reports of failing engines with burned pistons and valves from running too lean because the EGR has been deleted. you are asking me to prove a negative and that cant be done.

its not up to me to prove removing the EGR wont hurt the engine, you guys are making the claims that it will but don't have any proof to show that it has caused engine damage in even one case ever so the burden to prove your case lies with those claiming removing the EGR will do harm and damage the engine.

the evidence that removing EGR is indeed "relatively" harmless to your engine is in the lack of having these widespread reports of failing engines with burned pistons and valves from running too lean because the EGR has been deleted. like it or not some people rip out pollution control for no reason at all but if it resulted in engine damage or caused ill effects this would quickly be a well known problem and people would no longer do it.

I believe, "if its not broken then don't try to fix it" and "if its not broken then don't remove it just for the hell of it" but EGR removal has been going on since the 70's and there is still no pictures of a single engine that was damaged because the EGR was removed.

documents and reports are great but not long ago they had documents and reports saying we would all be dead from global warming and I would be 30 ft underwater right now but my feet are still dry and last I checked the world didn't come to an end.

data is great to have and can often be trusted and relied on but it also must be backed up with real world results and proof to show the data is making correct assumptions. were are the links to the pictures of the test engine that burned up when the EGR was disabled and the test results showing exactly how long it took it to happen and that it was due to not having the EGR?

 

Alrighty, no harm no foul. I looked into removing the EGR at one point, decided to leave it on out of sheer lazyness. If you do decide to remove it, consider dynoing your engine before and after for us. I doubt it would make much difference because it is supposed to be closed at WOT but it could make a difference at cruising speed maybe.

 

I think the only difference it "would" make is if you have one that doesn't seal well it can cause poor idle issues and that would be the only reason I would have to block it off, just to test for that.

from what I have read, it also might "feel" a little quicker to respond at times without it, but I think a lot of the reports of better performance are just imagined because I don't see how such a small amount of gas added can make much of a difference

 

On my 96 I had a hot start issue similar to what lovemytacolots is going through.
I can honestly say without a doubt my truck was more responsive from a standing take off and had a much better idle.
As far as more hp or torque i doubt it made much difference but as far as making the engine smoother it was night and day.
Now my 98 tacoma had problems from day one, i blocked off the egr as a trail and error on it and it never cured the problem but I left it blocked off and once my drivability issue was solved (fuel pump) i just left it that way

 

A dumb (or at least silly) reason to delete the EGR system is because you can't figure out why it's not working and throwing the CEL, not that I'm saying anyone here is doing that, but I've seen it in other car forums. The repair manual pretty much spells out how to test every part of the system (EGR valve, vacuum modulator, VSV, temp sensor) with a multimeter and hand-held vacuum pump. This and checking/cleaning all hoses and passageways should fix any problem.

I don't understand all the talk about a lean condition. The EGR gases are inert meaning they are CO2, H2O and nitrogen, but virtually no oxygen, so adding them to the mix won't affect the air-fuel ratio at all. Adding these gases to the mix just blocks the gasoline and oxygen from reacting as fast by mixing in between the molecules, essentially diluting the mixture.

As far as proving that deleting the EGR system will damage the engine, it's kind of like proving that smoking just one cigarette a day hurts your health. We know that a lot of cigarettes will hurt your health, so just one cigarette a day probably hurts your long-term health slightly. Likewise, deleting the EGR system will increase combustion temperatures, and we know if the temperatures get too high it could damages exhaust valves or other parts, so it's just a question of if the temperatures will get pushed high enough to cause damage, or how much quicker it will cause damage. Maybe this means you burn a valve at 390k instead of 400k. Maybe combined with a slightly tight valve clearance it causes a burnt valve that wouldn't have happened otherwise. Or maybe only under certain conditions like highway miles going up long hills it pushes the temps too high. I'm not sure. It sounds like it won't cause immediate harm based on other people's experiences with deleting it, but it could slightly increase the chance of long-term damage and increase emissions.

And as someone mentioned about the soot that is being recirculated into the intake, I think the the exhaust gas is mostly clean, and the buildup of soot takes many tens of thousands of miles, so I wouldn't consider this enough of a benefit to go through the trouble of deleting it.

Sorry I jumped into this thread a bit late. I don't mean to stir things back up, I just didn't have a chance to post earlier.

 

From what I've read most EGR systems will add somewhere between 6-10% of exhaust gasses back into the combustion cycle when they are operating. They are diluting the mix of air and fuel. So if you are using less oxygen, you don't need as much fuel for combustion. When functioning properly you don't have a lean condition.

 

I don't know if it was already mentioned or not but removing the EGR valve or system all together increases cylinder temps by upwards of about 500 degrees Fahrenheit which can cause premature wear on internal parts