Going to yank off the EGR. Yes I know the purpose of it and it's ups and downs ect. I found this link which gives me two block off plates. ARE THESE THE ONLY PARTS, that I will need to block off/remove the EGR AND not have a code thrown? ANy other parts that I will need. Please list...Thank you.


http://members.shaw.ca/korvette4u4/index_files/Page689.htm

It's supposed to throw a code through the EGR temp switch. This threads into the EGR, or at the crossover tube depending on year, and grounds out when it gets hot. If it's not there....


I say "supposed to" because mine was bad on my 85 and it never threw a code.

You could disconnect the switch and see what it does in a few days of driving before taking the car apart.

It wouldnt come on till extended highway use which I could put a piece of black electrical tape over the CEL BUT....I was asking if those two block off platles are all the parts that I need, I can rip it off install those two things, and not have a code thrown. No 0.00 about EGR except the basics of how it cools the gases, then it *can* cause soot in the intake which is not probabl enough to remove it for that reason. OTOH, why not remove it since we do not have emissions checks but even that is irrelevant to the case since people claim it adds horsepower which it does infact NOT. I just want to remove it for the sake of cleaning up the engine bay AND another good reason is because that they can/do fail and if the parts not there, then it cant fail such as the AIR PUMP...No pump, no failure, no EGR, no failure..As for hurting performance since it is not cooling down the combustion chambers/gases, my car does not make enough power to even significantly notice the decrease and might I add that I do not race/drag/autocross to begin with so again no performance lost, even though the performance lost by removing it is not going to be noticable. Bottom line, if it aint nessecary, it's gone. Also, the link I provided has nice looking AIR eliminator pumps but damn they are expensive. Reviews for them are in fact good and I have no doubt that they are not outstanding quality, it's just jeez, alomst 300 dollars. Anywho, if you know if installing those two plates takes it all off, prevents the code, and puts an end to the EGR, I will gratefully appreciate it because I am in the mood to remove excess parts that will not hurt performance and clean up the engine bay without taking required parts or chopping it up into some pile of shit....

On another note, when I installed those new gaskets, I can smell the sealant and oil really bad after shutdown. I hope that it will go away after a few heat cycles. Everything else is going quite well at the moment. Car seems peppier after tune up which is nice. :-) No codes are being thrown and if I get the EGR block off plates, it will be cleaner. Might I add for anyone who does not have headers but did eliminate the air tubing. You can take a dremel and remove the tubes welded to the manifolds and plug them. I am about to do that for the sake of making spark plug changing easier and again, they are usless.

Ok, let me try again.

All you need to eliminate the EGR without seeing codes is those two block off plates and a piece of electrical tape.

Much better....So whats the electrical tape go to?

To cover up the check engine light that you get from the EGR temp switch not being hooked up to anything.

Oh, you'll need to cap the tube on the header also.

Well allrighty. I did that b4. I got one of those covers that slips over it witha emblem. :D Upper middle class white trash eh?

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Where did you find that?

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http://www.ecklers.com/product.asp?pf_id=31586&dept_id=1600

Theres different styles...emblem no emblem Corvette LT4 ect...Gold white...

Nevermind...your post read as if it was a cover of some sorts for the EGR tube.
Son's vette came with one of those info center plates....it went into the trashcan on the way home.

How are you going to plug the holes in your exhaust manifold after you shear off the AIR tubes? Are your manifolds the stainless ones or the later cast iron? I wonder how thick the stainless are?

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Same way I plugged them...

Mighty putty similariites. Pick it up from Napa. Clay that turns as hard as steel. Worked great for me. Might figure something else out. I dunno what if they are cast or SS. Id guess Cast. They arnt that thick. Im cutting it down to the manifold. Not just the top part. Spray paint the entire manifold silver with high engine paint with ceramic and it is fine. Looks cleaner than stock regardless.

Talked to Agent86. He said he has been running with block off plates for no code for 5 years.

I wonder the logic of removing the EGR. It won't help performance and it will hurt emissions. Infact, it could hurt performance.

Your stock headers are stainless.

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Oh, you can weld a coin in the spot unless you have no EGR headers.

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Way ahead of you bogus....




EGR serves one purpose and one purpose only. That purpose is to reduce Oxides of Nitrogen (NOx). Under normal combustion, Nitrogen(N2)+Oxygen (O2) in the air and Hydrocarbons (HC) in the fuel combine into water (H2O) and Carbon dioxide (CO2) and the Nitrogen remains unchanged.

Under very hot combustion temperatures, the Nitrogen reacts with the other two byproducts and forms Nitrogen oxide (NO). After being released into the atmosphere, it picks up
another Oxygen and becomes Nitrogen dioxide (NO2). In the presence of sunlight, it combines with other compounds like Hydrocarbons and forms Smog. Since exhaust gas is inert (very stable) it doesn�t burn again. So by being introduced into the combustion chamber, it will lower combustion chamber temps enough so that the Nitrogen doesn�t react with the other compounds and is passed unchanged out the tailpipe thus not contributing to smog. Now, since exhaust gas doesn�t burn, it doesn�t exactly help with combustion. At higher RPM�s, this really isn�t noticable, but at idle, the reintroduction of exhaust gas will cause a very rough idle and can cause stalling if to much is introduced into the combustion chamber.

At WOT, EGR is not operational either, so you are getting the maximum out of the engine.


EGR Operation


Like mentioned before, EGR flow is good at higher RPMs, but not good at idle, so some sort of control needs to be place on the EGR system. Earlier systems used ported vacuum straight to the EGR valve. At idle, the throttle blades
are closed, so there isn�t any ported vacuum. When the throttle is opened, ported vacuum starts to build. The more throttle, the more ported vacuum. This is how
vacuum advance distributers work. As throttle is increased, the EGR valve opened further. Once the throttle is closed, ported vacuum is lost and the valve closed.

Most L98s (F and Y-body) use the basic diaphram EGR valve, but instead of relying on ported vacuum, it relies on vacuum that is allowed to pass through a solenoid.

The solenoid is controlled by the ECM. When conditions are right (I will give them later) the ECM will ground out the solenoid. The solenoid is a Pulse Width Modulated (PWM) meaning that the amount of vacuum is controled by the computer rapidly switching on and off to ground. The more vacuum the ECM wants to go to the EGR valve, the more time it lets the solenoid remains grounded, measured in Duty Cycle. With a scantool, you can command the EGR solenoid to
say 50% Duty Cycle and actualy feel the pulses if you put your finder over the vacuum port of the solenoid.




EGR Diagnostics


Now that you understand what EGR does and how it does it, lets see why sometimes it doesn�t do it. Since exhaust gas if being introduced into the intake manifold, things like manifold vacuum and airflow reduce slightly. Speed density computers can recognize EGR flow by looking for a drop in vacuum via the MAP sensor. (84, 90-93)

MAF systems use either a temperature switch mounted in the base of the valve or a diagnostic vacuum switch. Since exhaust gas is hotter than fresh air, it can pick up EGR flow by sudden increases in temp when the valve is open. The vacuum switch monitors vacuum going from the solenoid to the valve. In theory, if the valve is getting vacuum, then the system "should" be working. Highway speeds is when the most EGR flow is commanded. When cruising on the highway, the computer will pulse the EGR solenoid so that
vacuum will pass and go to the EGR valve. After commanding the solenoid on, it will look for signs that the EGR valve opened by one of the means mentioned above. If the ECM does not see the change its looking for, this is when the light comes on.
What are some possible causes of no exhaust flow?

Make sure that the solenoid is getting vacuum. A plugged or broken vacuum line will make everything else inoperative. If vacuum isn�t getting to the solenoid, it surely will not get to the EGR valve.

Make sure the ECM has control over the solenoid. Visually make sure that the connector is firmly seated into the solenoid and that the terminals inside the connector are not corroded or damaged. Usually you can rev the engine while it is in closed loop and it will be enough for the ECM to command EGR so you will be able to feel vacuum at the
solenoid. If you feel vacuum, than the ECM has control over the solenoid and adequate vacuum is reaching it. If you do not feel vacuum, you may need to drive the vehicle with a vacuum gauge hooked up to the solenoid. If you are driving in closed loop, you should see some vacuum. If you don�t the solenoid is probably bad, or the ECM is not controlling it (bad ECM grounds or ECM) providing you
had vacuum going to the solenoid. It is highly unlikely that you have a bad ECM, they rarely fail.

Inspect the vacuum line going to the EGR valve for plugging or being broken. It is not uncommon for previous owners to plug these vacuum lines with something to try and cure a �rough idle�. The lines can also become plugged with carbon deposits over time.

Check out the valve itself. Make sure it isn�t seized by manually lifting up on the diagphram. If it moves freely, put a vacuum on it. It should move and stay there (hold a vacuum). If it doesn�t move, try lifting a little on the diagphram, if it still doesn�t move, or wont hold vacuum, the valve is bad.

If everything still checks out OK, then the only other thing that will limit exhaust gas flow is plugged up passages in the intake manifold and cylinder head. This is a common problem with the V6�s and will leave many technicians scratching their head because the passages can�t be seen. Get a rifle cleaning brush and a shop vac and start cleaning.


Disabling EGR


Most people like to disable the EGR because they claim that hurts performance. In actuality, disabling the EGR can hurt performance.

As we already know, at certain thorttle postitions and RPMs, the ECM will command EGR operation. This is to cool combustion chamber temps under load.

Well, with cooler combustion chamber temps, we can further fuel economy by advancing the timing. We know that to much timing will cause �pinging�. But when we keep the combustion temps down, the timing can be advanced without the �pinging� effect. At highway speeds, the ECM commands EGR operation and will advance timing accordingly. With a blocked of EGR, the computer thinks it is flowing when it is not and will advance timing. Now that the combustion chamber temps are much hotter, the advanced timing is no longer a good idea and detonationoccurs. Since detonation can severly damage an engine, knock sensors are used.

When the knock sensor detects detonation, it will retard timing. It takes more to stop detonation that it does to cause it and this is where it hurts performance. For example, at highway speeds, your total advance may be, lets say 30* BTDC. If the computer advances it one more degree to 31* and it detects detonation, it can�t just go back to 30* to stop it, it must retard timing to like 25* to try and stop it, and if it still occurs it will further retard timing. If the EGR was working properly, the temps would have stayed cool enough to operate at 31* with no problems.

Now, if you ran into that problem of carbon plugging up the passages, and choose to disregard the above section, there are benefits to getting rid of the EGR totally.

First, you'll need to do the Diode Trick for the EGR, or have the Chip/PCM reprogrammed to take out Code 32 and EGR function, or you will get the SES light eventually. If its not during the startup check in the morning, you'll get it on the highway.

With EGR deleted, you'll no longer be injecting soot into your intake, which can plug up ports and get carbon stuck all over your valves. With a new engine I would not hesitate do get rid of it. If you have a race motor and are at WOT all the time, this wont be an issue since EGR is off at WOT. The clean internals you'll have are going to produce more power, for a longer duration than a street motor. Thats not to say a 110K mile 'vette cant put down its OEM numbers though.

Note about L98 vs LT1.

1985-1989 V8:

These systems use a typical EGR valve with one exception. There is a Diagnostic Temperature Sensor threaded into the base of the EGR Valve. Because these cars are equipped with a MASS Air Flow sensor, it uses this temp sensor to detect changes in temperature. Primarily, it is looking for a sudden rise in temperature when the EGR valve is opened. Everything is the same as mentioned above, with the addition of the temp sender. It is wired directly to the ECM, and serves as an EGR self diagnostic only. Some potential problems that would cause a code on these systems are: Ruptured EGR diaphragm, broken vacuum lines, defective or plugged EGR Solenoid, poor connections to the solenoid or diagnostic switch, or a failed diagnostic switch

LT1
These systems use the same EGR valve for the previous V8's, except the deletion of the Diagnostic Temp Sensor. Because these systems are Speed Density (using a MAP sensor) it can detect EGR operation in another way. Usually the EGR diagnostic is run on a long decell. When the vehicle is in decell, the EGR valve is closed. The ECM begins to monitor MAP sensor voltage very closely, and will cycle the EGR Solenoid to open the valve fully and then closed again and watch for the sudden changes in MAP sensor voltage, due to the introduction of exhaust gasses into the intake. Failures for these cars are similar to those on the previous V8's, except the temp sensor, since it is deleted.

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Make sure you get EGR plates that wont rust. I somehow ended up with one that is rusting and one that is good.

So I went out to the car with my dad and was showing him what the EGR was and he informed me that the pipe that goes on the manifold has a crack in it. I get a closer look and it is indeed cracked witha hole in it. I followed the wire and it was unplugged! It has been this way for a while apparently because neither of us has touched it. He noticed the crack the other day when we were cleaning up the bay. Interesting and I have not had a CEL on. No electrical tape needed. Ill order the plates and store the EGR for future needs. Much thanks everyone for the input. Oh yes, I snapped a few pictures of it. Also, I am snapping pictures of my door panel restoration. Paint, new inner seal, new door piece, scrub down the door lighting, new carpet, using some gorrilla glue and other stuff to patch up the cracked plastic inside the door panel. The paint has made a HUGE diffeence as the dawn soap has on the dirtly light lense. Wow. I am still scrapping off glue.

Well like I said, mine never threw a code either. But the manual says it should. Go figure.

Thats pretty pathetic that GM can't even make a car throw a code when something goes wrong...So what do i do with the sparkplug looking thing and the plug in piece that are connected???

Toss it with the rest of your EGR parts.

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Hi,

my 383 is a new engine and I consider to block the EGR or not. The CR is approx. 9.5:1 due to getting a supercharger in the future. Cam specs are 214/224 duration 531/568 lift 115 LSA (the engine-builder recommended this).

So what do you guys think ... is it a good idea to block the EGR?


I found some specs for the stock cam on the internet, btw: 90-91 L98 10111773 In/Exh Dur@.050" 202/207 Lift (w/1.5) 413/428 LobSep 114.5

Here is what the EGR does:

1. Control NOx emissions. How tough is Germany on this standard? If they test a 91 on it, you may need to keep it.

2. Controls detonation. The same trick it does to control NOx also controls detonation.

How? A small amount of exhaust gas is added to the intake charge. This lowers the temps inside the combustion chamber. This in turn lowers NOx and detonation.

LSA has a lot to do with NOx emissions, and I am not sure if the LSA for your cam is going to help or not.

No real benefit to removing it engine-wise. It does clean up the extra clutter in the engine bay.

Mine was tuned out a long time ago. Then a couple of years ago I pulled the tubes and the rest of the EGR equipment. Makes removing the intake/checking for leaks etc, much easier.



Mike