I have put the S_AUJP that Trax has put together in my car and wanted to ask a question that has probably been asked before.

Does the car run better with EGR enabled or disabled? Some say it runs better others worse anyone done some testing on this and have any results?

Just asking cause the S-AUJP CCP bin has the EGR disabled.

 

Enable it and see how your car likes it. That's the beauty of being able to burn your own chips. You can test out things like that and you know the only difference is that you changed one value.

Give it a shot and find out.

 

EGR shouldn't have any effect on performance.. its main function is to lower combustion temperatures while cruising on the highway.

 

Build a little cat's whisker movement detector, and look at what the pintle actually does.

Backpressure is enough to open most of them.

Adding hot exhuast gases, raises the manifold temp., and the manifold being hot, heats the air passing thru it.

 

With and without EGR means changing the timing, and fuel to compensate for it. So you have to tune for both conditions to really find out if your engine likes it or not.

 

Disable it and forget it.

I know a lot of you believe what you write but there is no way the egr cools the combustion chambers. I understand your theory that inert gases (burnt already) are being introduced instead of fresh air ( burnable oxygen) whichs lowers the volume of combustible material in each cylinder.

BUT here is the problem with this theory, those inert gases that are being introduced are at exhaust gas temperature, a heck of a difference from cool fresh air.

I don't want or need my engine to have to ingest hot air, cool, denser air makes power, hot exhaust gases will hurt performance. I also do not need the carbon building up on my intake thanks to the egr. If your engine burns a little oil ,might even get a nice oily, carboned up mess in the intake....oh...yeah I can't wait to force that down my engine's throat.

Too many people including myself have disabled the egr with NO adverse affects , DO NOT need to adjust fuel or timing. Put a plate under it, reinstall it, looks like it is working in case the smog police have a look under the hood. On a TPI you may have to just put the plate only, not sure.

It would be nice to turn the egr off or set the test to a higher temp in the prom for no more SES light .

Argue all you want, cooler air makes more horsepower, unless you like your engine to ingest hot, dirty, possible oily air that carbons up your intake.

Disable it, your engine will thank you.


Bill E.

 

I can't agree with you on everything you said so here is something to chew.
It's a fact that EGR will lower your combustion temps and combustions temps can be seen (if you don't change ignition timing) in EGTs. And EGTs are lower, combustion temps are lower.
Now to get to your point about EGR hurting your engine. Let me ask you what puts more wear and tear on an engine, one that is burning less fuel or one that is burning more, same engine, just different fuel consumptions. Running EGR could increase your engines life if you do a lot of highway driving or if you have lots of rear gear and are spinning the snot out of your engine on the street.
I do agree with you about the oil consumption but trust me, it won't be oil from the EGR, it'll be carbon. If oil isn't burning up through the combustion process then you have other problems. The only way oil will be ingested is through the PCV system. If you still have a functional PCV then the oil in the intake is 99% from that, not EGR. Oh, and the carbon that does go through the intake when you're running ***** to the wall will most likely pass through the engine with no troubles.
Weigh the reasons before going one way or the other.

 

The fuel isn't perfectly homogenious in the chamber.
EGR helps to limit the peak temps within the chamber.

So the peaks are lower, and in that reguard, it does slightly lower the temps..

And beings the added gases are usually hotter, it does lower the threshold to pre-ignition, and detonation. In some of the newer stuff they're making an effort to drop the EGR temps, pre intake runner.

 

Okay Grumpy I am going to ask you straight out.

Would you enable EGR or not?

And at what temps would you have it enabled at if you did use it?

 

WRONG,

Ask any tuner, cooler denser air will allow for more timing. That wonderful EGR is introducing hot gases which is more likely to
cause detonation.

For example, a Hypertech thermomaster chip....more timing dialed in so therfore they want a free flowing exhaust to remove exhaust gases to lower temp and a colder thermostat.

An another example would be supercharging , raises inlet temp due to compression which without an intercooler to remove the excess heat you would need to retard timing.


Bill E.

 

Egr lowers combustion temps compared to what ? A fully filled combustion chamber with cooler, denser air .

Theoretically since I am burning a cooler denser charge , fully filled chamber, and making more power, I could back out of the throttle compared to an EGR car. This is silly egr does not help out mileage or longevity of your engine.

Common sense and basic engine operating principles people,

I am a jet engine mechanic, build 'em for a living . These engines make more thrust on cool day than a warm day every time. Push them less on a cool day = engine longevity vs. push engine harder on the warm day to get same thrust as cool day and it'll be off the wing and in the shop way before the engine ingesting nice cool air.



Bill E.

 

Might reread what your claiming is wrong.

I said it lower the threshold for detonation. That means it is more likely to detonate.

The hyper stuff is about laughable, for years all the did was lower a few enable temps, and usually only the fan operating temps.

Ya, when I get a chance I'll ask a tuner, ya know any?.

 

I've tried several times to get the claimed benefits of running it, and to date, I've never seen any gains, in off-highway use applications.

 

Well, EGR is used to lower combustion temperatures. In this manner it lowers the exhaust emissions of NOx. Don't have to believe me, here is quoted text and a reference:

"Higher combustion temperatures induce an over-proportional increase in NOx formation, and because exhaust-gas recirculation (EGR) reduces combustion temperatures, it represents a particularly effective means of controlling NOx emissions."

Automotive Handbook, 5th edition, 2000. Bosch, Robert. Stuttgart. p. 520, para. 1.

This is from the section titled "Exhaust emissions from spark-ignition engine." Just so there is no misunderstanding that this is for some other type of engine.

RBob.

 

Okay Grumpy, seeing as I hardly ever see the highway with the Chev I will leave it disabled and see how the car runs for the time being.

cheers Mike

 

The exaust gasses are oxygen deprived and only contain small ammounts of avialable energy (since its been burned already) so mixed with the intake charge they make for a cooler burn since the energy rich air/gas has been partially replaced with the burned exaust so less energy is available. You even need some timing added in when the egr is active so the engine performance at part throttle doesnt suffer. Some manufacturers even tinker with the cam timing to get an 'egr' effect to cool the combution temps and reduce harmful emmisions. GM did jsut this back in the dark days of smog by taking some advance out of the cam.

 

Sorry I did misread you on lowering the threshold of detonation, so we agree EGR gases will lower the theshold for detonation.

Sure, the hypertech is laughable, but it is given as an example only that lower temperature intake air will allow for a more aggressive timing curve as opposed to a warmer intake charge.

A tuner, ask TPIS OR LINGENFELTER, they all will tell anyone that cooler makes makes more power, period.

Bill E.

 

Let's say for a moment EGR lowers combustion temps which it does not......it would be doing it at the expense of power because you are ingesting spent HOT gases into your combustion chamber instead of burnable COOLER air.

If it is such a GREAT thing why is EGR off at WOT, because it is costing you power.

You EGR guys keep smoking whatever you are, I build jet engines for a living and these engines operate under the same basic principles as any other engine that requires fuel and air ( about covers them all don't it)...

Cooler denser air will ALWAYS make more power or thrust than hot air and the cooler charge will be much easier on the engine because it will not be on the ragged edge of detonation.

ANy cooling effects of adding inert ( spent) gases into the mix are more than offset by the increase in temp associated with the inert exhast gases.

Smoke 'em if you got 'em, oh forgot you guys already are....

I am done with this , basic engine principles apply to every engine made, EGR is for emissions, no other benefit...period.

 

You're not thinking straight. An engine designed for thrust has almost no bearing in the automotive world other than they both convert chemical energy into mechanical engery.
In a car on the highway it doesn't require much horespower to sustain a constant cruising speed. Take that and chew it. There are 2 kinds of highway driven vehicles. Those that are geared for acceleration at low speeds and only have the throttle open to sustain an engine speed, those higher engine speeds are creating more heat from yes, more fuel BUT more timing (lower map loads) than an engine with more TPS and lower rpm. BUT those cars that are using slightly more TPS because there gearing is designed for keeping the engine lower will still burn less fuel and gain mpg if it is making enough torque at that vehicle/engine speed to maintain cruising speed.
I don't care what you think but saying EGR is nothing but an emissions tool is . It's implementation might have been only for emissions but so was EFI. And please don't go and tell me EFI is only good for emissions or I'll have to reach through this monitor and bitch slap you.
Plain and simple, EGR will lower combustion temps resulting is less fuel, less fuel will equate to less power and a given constant engine speed. At 65mph spinning at 3000rpm if you're making a lot of power you can gain some mpg with EGR.
Oh, and a hotter intake charge will help with the homoginious intake charge resulting in again the ability to increase timing. I can argue this till we're all blue in the face but the increase in intake charge temps will not result in pre-ignition. Another mis conseption is that run the most timing possible without pinging but unless you have a calibration that removes timing as speed increases you will be shooting yourself in the foot. That's already been brought up so do you think that's BS too?
I'm sorry you had to go and bring up your "experience" but let me again state that you're experience doesn't make you any smarter or wiser than the other man.

Mike, disable it in your situation. You'll be better off until gas prices increase to $4/gal. When that day comes we'll probably all be running water injection on our n/a cars!

 

One thing to remember is that the intake charge is compressed a great deal, both in jet engines and especially combustion engines, to very high temperatures so the initial temperature of the charge isnt quite as significant in that regard. Its really significant in that the colder air is denser and allows for more oxygen to be present overall. That means the potential for more power. What egr does is displaces some of that air/fuel charge with spent exaust so the air fuel charge becomes more defuse. This means less overall energy and a cooler burn. EGR is a must in this day and age with unleaded fuels and higher compression. Without it, cars would have not only high NOx emmisions, but also problems with detonation that would require that less timing is run. EGR to some extent helps cope with that by giving a greater margin untill detonation. My 8.5:1 engine doesnt need it, but an engine with 9.5:1 or possibly 10:1 would really demand egr if its to be run on average grade fuels.

 

One of the reasons its off at WOT is that theres no vacuum to operate the valve or motivate the exaust gasses to return into the plenum to be reburned. Plus giving the engine a facefull of its own **** at WOT wouldnt make much sense, would it

 

So far TPIS hasn't impressed me.
And in talking with Jason Haines at Lingenfelter he has impressed me.

Care to try some more name dropping?.

BTW, Jason dropped by the house for Pizza a few years ago.

 

I guess you never actually tested the EGR operation on a 3rd gen have you?
Backpressure will open the EGR valve.

Instead of bailing you ought to hang out and maybe learn a thing or there instead of assuming you know it all. While some of what you said is true, not all of it is.

 

Build a darn cat's whisker position detector and get back to me.
PLEASE.
BACKPRESSURE WILL OPEN IT.

Yes, EGR in some applications (like the 3rd Gens that this list is specifically for), does open at WOT.

Yes, they taken measures in the later stuff to prevent it, or better manage it.

 

I haven't the time or the energy to go over basic engine theory with you. Try reading a book , egr WILL NEVER HELP YOUR MILEAGE....what an idiot.

My experience is irrelevant, I guess it is when dealing with idiots that refuse to acknowledge basic engine principles, cooler air makes more power than hot air....period. Jet engines run on air and fuel, don't they.....jet engines make more thrust (power) with a cooler denser air charge....push engines less on a cooler day and therefore burn less fuel than a warmer day....How is this not applicable, I mean you said jet engines have little to do with this ?

What is your experience, maybe a desk jockey, built any engines lately, dynoed them, I have......You pipe in cool outside air ...guess what happens....low and behold a few extra hp.

What you can't get through your head is the offset of any gains because of the increase in temp of air intake due to hot exhaust gases being introduced.

Your theoretical increase in mileage is

But I'll play, my engine making more power on clean, cooler, denser could back out of the throttle some compared to your engine breathing dirty, hot exhaust gases, theoretically, of course.

Engine theory 101..........Give me your best shot...

Bill E.

 

If it is opening under WOT , it should not be, that is just what you don't want especially at wot .

I guess they have "taken measure to prevent it" for a reason ?

Must not be a good thing to have that EGR open at wot ? Actually it is bad thing to have the EGR open ever.

 

Never assumed I know everything, just some things like basic engine theory which some folks can't grasp and so therefore
insist on forcing hot exhaust gases down their engine's throat.

If hot exhaust gases are such a wonderful thing, I wonder why turbos have INTERCOOLERS ?????? Obviously the quantity is much different here, but the basic principle is the same, cooler air is better.

"Maybe learn a thing or two"

I don't think you two could teach a duck to go to water.

 

Which types? Digital types? Positive backpressure ones? Id assume your reffering to to designs that use the exaust back pressure to provide part of the signal that operates the valves? How much do they open? I couldnt see much more then leakage on a car with a decent exaust system with a vacuum operated egr valve. Ive always been partial to the regular old vacuum operated ones myself. Dont have to worry about the lack of backpressure from a good exaust system stopping it from opening when it should.

The only one that would really open up all the way is the pintle type that was run by the pcm in my s-10. At wot, it would open fully and allow crap from the roof of the CC to enter into the valve and plug it up. Mustve blocked open about 10 times before I just unplugged it for good.

 

You are a joke. You think you know it all but guess what, it's time for me to whip out the big guns for the pathetic person sitting in front of your monitor.
Funny you mention the whole "how many engines" and have you tuned an engine on a dyno.... I have just finished tuning a motor on a dyno tonight, yes tonight, about 10 minutes ago to be exact. Been working on setting up our engine in the grad students dyno for the past few days and it fired up last nite. Want a picture, I can send it.
Oh, and RBob, the wideband is working great. We even have an actual NTK controller that was given to us to use for the weekend, I told them we didn't need it . Have you ever seen their insides, if not, I'm your man.
I still don't see where you're going with this "cooler air is better" BS when we're talking about milage, not power. Oh, and BTW, intercoolers aren't all they're cracked up to be if you know how to lower the intake temps using fuel and/or water.
I can't believe you had to go into the name calling, are you really a jet mechanic, because you're starting to place doubt in my mind.
EGR can increase your milage for some applications. I never said it wouldn't and could you please quote me where I disagreed with the cold air more power statement?
I think you need to go back and re-read my reply.
I also can't understand why you think that just because you're using less throttle, that you're burning less fuel than somebody with the same throttle position and hotter air. Again, have you ever looked at how much power is really needed to sustain vehicle cruising speeds. Next thing you'll be telling me is that your modified engine gets better milage all around town then you're stocker because you have to use less throttle . When you ever get to understanding more than the basics, we can have this little chat again, you might learn something. If it were as easy as you claim to make a perfect motor I think the Automotive engineering world would be out of buisness. What is your understanding of BSFC, engine efficiency, combustion chamber efficiency, and everything else that is critical to an engine tune? How about understanding on resonance tuning and exhaust tuning? What about pumping losses through different components and various parasitic drag? How about your knowledge of various waterpump designs and cooling systems along with ceramic coatings?
Let me make you feel even smaller since you felt it the inclination to call BS on me and call me an idiot. When was the last time you saw a thirdgen gasoline powered vehicle with no direct drive thrust propultion.... because that's about all you would be standing on in this little arguement.
Grumpy, I understand that under backpressure EGR will open, this is old knowledge to me, okay, maybe only 3 years or so.
Oh, and for some of you that are interested, I was tuning an unrestricted Honda CBR600 F4 up to 12500rpm.

 

You started off with this same attitude that this post is dripping with , something about a bitch slap, what an ******.

"Just dynoed one 10 minutes ago" REALLY

"You can't understand why I think if I am using less throttle that I would be burning less fuel " compared to the exact vehicle except with egr. Too much for you to follow. Besides makes about as much sense as your bs on egr helping mileage and I was just theoretically "playing along" with that scenario.

Damn dude, you should have been a rocket scientist. Or a world class engine tuner ( thinks he is) that should have some test data backing his claims to better mpg with egr.


You brought up this bs about mileage, not me, sounds like you'll admit EGR hurts overall power output.

Said in other posts I don't claim to know everything, back up your bs about mileage increase with proof.

This time I am done, I don't deal with ******* or idiots and you just doubled down....

 

This has caused me to drop $45 on a book! The book that RBob quoted, I've heard that it's an excellent resource. Automotive Handbook by Robert Bosch. Just went to amazon.com, and I'm about to order it. I know htere's much more there than I'll ever get a grasp on, but I know I will learn SOMETHING from it!

Now back to topic.....

I'm sure EGR DOES decrease overall power, and I bet everyone will agree that when you put less air/fuel mixture in a cylinder due to the fact that some exhaust gasses have been allowed in there at the same time, you will decrease power. Driving down the highway, I bet it's barely noticeable due to the fact that it takes far less power to ACCELERATE TO a speed than to MAINTAIN a speed.

Makes sense to me that if you have less air/fuel mixture to burn, you're going to generate less heat, even if the inert gasses that cause there to be less air/fuel mixture are hot. It all becomes extremely hot when compressed. There are engines designed around this principal! I think the guy that came up with it had a last name of diesel.

Now, I don't currently run EGR on my engine, have no problems with detonation, etc.... and I really doubt I will be running it in the future due to the difficulty of hooking it all up (vortec type, aka fastburn heads) but if the provisions were there, I think I would keep it working.

As for engine longevity, look at all the 60's engines that were worn out before 100,000 miles, then look at my 84 LG4 305 WITH EGR that run until 215,000 miles (still would be if I hadn't pulled it!) and all the other newer vehicles that last a lot longer than the older stuff. I can't believe that EGR has much, if any of a negative impact....

Now, even though I've argued in favor of EGR, it does seem sort of silly to put the **** that is a by-product of combustion back into the engine, that would be like eating your own.....well nevermind, I think we all get the point. The strange thing is that it must really work, or the OEM's wouldn't be using EGR......

 

Hallelujah. Go back to sitting on the porch at the crack shack.

Pick a thought and stick to it. You keep bouncing around between mileage and power so much that it doesn't seem you have a train of thought.

Want to prove you're "king of automotive knowledge" [which you've claimed not to be a few times already], go burn a couple of chips and give datalogs stating that EGR has no effect on mileage. Then we'll believe you. Until you give us hard proof [or mildly solid, lol], you might want to take some inert gases out of your ego before it explodes.

My $.02 on the whole deal, I had a malfunctioning EGR like most 3rd genners do. I installed a chip where EGR was disabled and went from 14MPG to 21MPG on the highway. Do I care if EGR gets me more mileage? Not right now, I'm still damn happy with a 50% increase. Will I check it out later? Maybe, but right now I've got other things to take up my time.

 

How funny, like I said, so some testing and you might be surprised at the results.

Just because you read something doesn't mean it's true.

 

Any one you'll find on a 3rd Gen..

This list is supposed to be third gen specific, so unless stated otherwise, the Charter would govern the fact that the info. being related too would be 3rd gen specific.

 

60s engines that wore out before a 100,000 miles?.
I was driving back then, and that wasn't the typical case, from what I saw.

With all the fuel changes, and improvements the comparison of 60s engine life to now, really isn't fair. Not to mention lubricants.

Bearing wear (assuming the tune is right), is primarily about bearing loads, and oil temps.. Rings are about filtering material.
While the new low tension rings may help with cylinder wear, They're more for MPG.

 

I was reading an amsoil article and they were stating the same fact that engines from the 60s compared to modern cars dont have alot of the same characteristics. For one the materials tolerances and quality control of older engine parts was not as scrutinized as much as today. And like already stated the new formulas for lubricants to last for better mileage has also improved. I think up until you put all these considerations into play then you can have a good argument for this statement.

 

I guess I was typing faster than thinking again, so maybe I don;t have anything on the longevity issue.

Well, I tried, and thanks for setting me straight.

Now I'll just leave it, and not argue unless I find some PROOF either way.

 

Guess the stock 3rd gen exausts must suck more *** then I previously thought. Unless the high pressure region in front of the exaust pulses is causing the valve to lift off its seat.

 

double post...

^ took that message forever and a day to get there.

 

This should explain GM's purpose behind the EGR system, in Service Manual language.

 

Bottom line......if the australians doesn't need one then I dont either

 

Just remember Service Manual stuff is written to be easy to understand, and they have been known to cut too many corners on their explainations.

PARTICULARY, in the emissions area.