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Old 05-03-2002, 07:43 PM   #1
tonytiger
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Question Disabling EGR valve: how to, have anyone done it?

This was previously a topic here, but nobody didn't at the time know the answer concerning the mod.

Few questions before I start to look for the EGR valve at the engine compartment:

Will it cause CEL? If so - why it causes it?

Is it ok to just plug the hoses with something?

Will it lead to knocking?

How to do the mod without destroying EGR valve itself or/and the EGR control solenoid?


I read about the issue from a tuning book which just adviced to plug the holes leading to the EGR valve and that was about it. Benefits of doing this according to the book was:
better gasmileage
emissions beside the NOx will reduce
and of course some more power.

Drawbacks was:
NOx emissions will increase and a possibility of engine knocking.

It didn't say which car was modded, but a local tuning magazine here where I live had a Ford Zetec engine with the mod.

Emissions shouldn't make anyone to have bad conscience, since the system was originally made for cars to pass the emission tests. Emission test limits sometimes leads to unreasonable results...(says the book at least

However, I seriously doubt the knocking to be an issue without increased compression ratio.


Thank you in advance.



tony
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Old 05-03-2002, 08:31 PM   #2
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Quote:
better gasmileage
emissions beside the NOx will reduce
and of course some more power.
hmm.. what book are you reading, those are the Bennifts of EGR system not the drawbacks.

your car will run very poor especially on the highway..where the egr system is used the most, it is set up to run with an egr system..you will most defintly have a CEL

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Old 05-03-2002, 11:06 PM   #3
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To disable the egr just unplug the vacuum line to the egr valve and plug the vacuum line. It shouldn't cause a cel. There is not much gain from disconnecting the EGR.
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Old 05-04-2002, 08:24 AM   #4
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But why would you want to disable it though? It is part of the emissions system, It should cause a cel.
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Old 05-04-2002, 07:18 PM   #5
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Why would this give you a gain in power? The engine and ECU are set up to use the EGR, and if you disable that, you'll just confuse the ECU. I don't see how it could make the car run that much better. Anyone have a diagram of the EGR system, maybe if I saw a pic of it, it would make more sense.
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Old 05-05-2002, 02:45 AM   #6
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EGR systems are set up to be used under cruising speeds only, they open based on vaccuum on these cars. WOT=zero vac=closed...don't waste your time, also your combustions temps @ cruising speed will reach up to 2500 degrees and also your emissions will increase as well as your gas mileage decreaseing.

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Old 05-05-2002, 08:10 AM   #7
tonytiger
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Thank you for the answers.

The book which I read about it was written in Finnish, but it had an american author. I can't clearly member the name of the book, but it somehow could be translated as: The modern engine - tuning and fixing. It had about 250 pages.

The author of the book was very convincing with his writing and I think he even had some competition background.

Why would my gas mileage degrease and my other emissions increase- the gasoline is burnt more efficently when there is now exhaust gasses spoiling the mixture?

This also leads to a question of the ammount of the recirculating: why not increase the amount of exhaust gas in the cylinder for even better economy and environmentally friendliness?

If it as WOT closed and at normal cruising speeds open, wouldn't you get a minor lag when stepping on the gas. What about switching to lower gear with clutch engaged and for example cornering: For a while the engine is not nearly at WOT and when you want to step on it you get the lag.

However I can't figure out how would one get more power due the controlling system - that sounds reasonable.

HondaH8er: do you have any Haynes repair manual, there should be picutre of the diagram.

Our ECU should learn to give the rigth sparking advantage and control the mixture.
It might cause our engines to run lean at cruising speeds since the ECU thinks there is unburning compound in the mixture which will not need fuel since it won't burn.

Why does the combustion temperature rise? I can see it's obvious that with the EGR it will decrease since the production of the NOx will decrese, but why does it happen?

I don't see any EGR in race cars...

Avenger: Shouldn't be a difficult thing to do then. Have you done it with some car or do you have a friend with the system off?



tony
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Old 05-05-2002, 11:21 AM   #8
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I dunno how to but my buddy with a supra tt has disabled his & I know alot of toyota guys do this when they go single turbo.

goodluck

-justin
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Old 05-05-2002, 02:40 PM   #9
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Quote:
Originally posted by tonytiger

I don't see any EGR in race cars...
you don't see cat's on race car's either so what's your point?? but i'll tell ya what you do see...on average a $40k-$100k power plant which is replaced every race. They run them super rich for long periods of time and beat the snot out of them. why do you think they get 2-3 MPG?? There's alot of theory here....your EGR system allows and inert gas to enter the combustion chamber to take up space(less air and fuel) so that your fuel economy will increase at cruising speeds. Now wether you believe me or not is a different question but there is NOT much performance gain by disabling it. You may get 2-3 flwyheel HP MAX output more. worth sacrificing mileage and durability, not to me.

jeremy
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Old 05-05-2002, 03:26 PM   #10
tonytiger
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It's not an issue of believing, it's an issue of questionabling - with all respect.

You wouldn't see cat on my car either if it wasn't the law here

The racing engines are way out of our budget and the life of curve of the those engines are minimal in comparision to our engines. However, the EGR system isn't either used in low budget national series cars here at my whereabouts - those engines aren't replaced after every race.

Issue what supports your theory about the diverseness of the racing enginess is the programable engine management. The timing and mixture can be changed for the need.

Why did you change your oppinion of the WOT statement? It's a correct statement and leads to conclusion of no max HP loss due the system.

The inert gas won't be burnt, neither does the gasoline at your fuel system before the injector. You don't have to feed any less or more fuel to get the same output of the motor; the air drag and other drags will need the same amount of power to get the net force of the particle to zero. It's a fact, but as said before the engine management isn't perfect - neither it's a perfect with the EGR on.

Blindeye_03: Do you know the reason why they do the disabling when changing to single turbo?

Mazda RX7 has an EGR valve open at specific RPM range(!) according to thisinternet page , which will affect the acceleration. What about our Subies?

Not much to gain (if at all regarding the power), but for nearly free - I hope

Thank you all again and HndaTch627 specially - it's the conversation which leads to knowledge.



tony
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Old 05-05-2002, 05:04 PM   #11
Evan J. Kelly
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Lightbulb

I got this for use on my upcoming v.III STi type-R...

This is for a fuel vapor controller, but he starts to mention(I think)about what you want to do in his last statement...
Maybe you could do both?
__________________________________________________ __
Hi Evan

I removed the carbon can, support bracket, drain pipe from can, pipe from can to intake manifold, pipe from can to fuel tank.

I plugged the redundant ports on the manifold and the fuel tank.

I then drilled a 1/8" hole through the centre of the fuel filler cap.

I believe the later models had a control valve on the purge line under the intake manifold. You can either plug at this valve or remove the valve but this will give a CEL unless a resistor is connected across the feed wire.

You can also pull a lot of the engine breather pipework off, those blowby gasses feeding back into the intake don't help power.
__________________________________________________ __

Trying to help, dunno much about your application though,
-Evan
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Old 05-06-2002, 10:27 AM   #12
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Quote:
Originally posted by tonytiger

Blindeye_03: Do you know the reason why they do the disabling when changing to single turbo?

tony
Tony,

I cant remember all that well (A.D.D. ...)But he said something to the effect that the people that dont put blocking plates on the egr get burnt valves on cyl #5 & cyl #6 (closest to the firewall).


Here is a link to Supra Forums...I did a search for EGR, and you will find out more facts by going here: egr on supra forums

later,
-justin
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Old 05-07-2002, 05:59 AM   #13
tonytiger
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McDade: I believe question about the book was sarkasm, but I think the author of the book was Graham J. Bell. It came to my mind suddenly.

After searching a lots of information the main issue, issue of the power, will depend whether the EGR valve is opened on the basis of RPM or strain.

Other things like the combustion chambers heat production has also been discussed.

Here's some basic fysics.

To achieve non acclerating speed of the vehicle the same amount of fuel has to be burnt, considering the same vehicle. If we feed air to the cylinder we have to feed approximately 14,7 times the mass of the air of fuel to the cylinder to get emissions under control.

If we feed inert gas (exhaust gas) along the air we do not have to feed the gasoline at the same 14,7 to 1 of mass ratio - the ratio can be smaller.

When the air fuel mixture is burnt the amount of heat produced is proportional to the mass of the burnt products.
If we can fill a part of the cylinder with exhaust gas, which temperature is smaller than the just burnt mixture, the heat of the burning process will be smaller.

However there is more of the hot gas than when burnt a smaller amount of air by itself, the amount of thermal energy is bigger(!).
Because of the EGR, the heat production of the engine, engine's heating, will be bigger.

It's like having two litres of hot water instead of one - in other respect of course.



The issue about mileage is short:

To get the air mixture burnt perfect the mixture of the air and gasoline has to be as pure as possible. The result of the EGR to mileage has a similar effect as decreasing compression ratio. The effectiness of the burning prosess will suffer; emissions (besides the highly temperature sensitive NOx) will increase and the gas mileage will get worse.



Issue about possibilty of knocking is related to the heat of the burning process. At same volume(!) the pressure is proportional to the temperature.
When we feed the inert gas we therefore however increase the volume of the gas.
Whether it causes pinging or not depends on the amount of inert gas recirculed and it's temperature. Therefore I can not say will it cause knocking, pinging or not.


So I'm at this point going for it if I get the information of how to do it and the issue about CEL. I doubt the EGR in our Subies is directed by the basis of the RPM so the gain of power will on that basis vanish, iff we have a perfectly operating system! I have over 100000 miles on my Subie.

Might forgot something...



tony
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Old 05-07-2002, 12:39 PM   #14
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FWIW, the 00-01 (not sure about the 02's) RS's don't have egr valves. I'm just wondering what that means if Subaru dropped this particular facet of their emission system on newer cars. Is it really THAT necessary? Doubt it

I have disabled the egr system on my 97GT by dropping a 01 2.5L engine in my car using the original ecu. If you're wondering, you WILL get a CE light by disabling the system. The ecu monitors the mechanical valve by operating the egr solenoid. The solenoid opens the valve and the ecu checks for o2 sensor values before and after solenoid operation. That's how it knows.

Believe me, I've tried every single method ppossible to trick the ecu into thinking the egr system was still in place . . . no luck. Every three days or so after an ecu reset I'll get a CE light (only while I'm at cruising speeds). I just wired in a switch to reset the computer from within the car.

Jason
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Old 05-07-2002, 06:40 PM   #15
tonytiger
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2.5GT:
Have you ever get piging/knocking after you have dropped in the new motor? Will the check engine light come on because the engine detects knocking and advances the timing therefore.

After reseting the ECU will the ECU learn the new spark advance graphs? Has anybody a clue of this?

How can the knocking be noticed - can it be heard?

According to the Haynes repair manual the EGR control solenoid should have a resistance between 10 to 100 ohms. If you still have the control solenoids electric cords, use a resistor to connect the lines - maybe it helps.



tony
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Old 05-08-2002, 09:13 AM   #16
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As far as I know, there is no audible knocking (it runs no different than with the old engine, except that it's faster and doesn't overheat). If there was knock due to egr removal, it would only be present at cruising speeds, where the egr is activated. I haven't had ANY problems without an egr system.

Jason
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