egr valve

[gg250cc]

i was waundering if the egr puts fresh air from the intake into the exhaust stream, or dose it put exhaust gas into the intake stream? and does removing it add any hp?

[slipnfall]

... if the egr puts fresh air from the intake into the exhaust stream ...

No, other way around. I believe the above is achieved through another valve, but am not certain.

It feeds exhaust gasses back into the intake manifold to aid in reducing tailpipe smog. Since this recirc'd gas is highly inert, it will not burn in the combustion chamber. This doesn't exactly help performance, but it is only(rarely) noticable at lower RPMs. It will however, help to bring the engine up to proper/efficient operating temp. At that time the recirculation should be minimal anyways. There's tons of info on what exactly(chemically) this valve is to achieve. google it!

IMHO, if you don't have emissions to worry about, take the sucker off and cap the intake(don't forget the exhaust feed too!). If you must keep it, take it off and give the ports a good cleaning with some good 'ole carb cleaner. They can be quick to clog.

[edit] And no, you will not gain anything by removing it

HTH-Slip

[pmkls2]

I hate to bust your bubble slipnfall but if you just take the egr valve off without recalibrating the ecm you are looking for trouble. The ecm is mapped to adjust the fuel mixture for when the egr is supposed to be open. If you just remove the egr valve and dont change the calibration to compensate for this you will end up with a lean running engine and you could cause internal damage(I know people do it everyday and dont ruin their engine but are you really willing to take the chance?). Unfortunately if you dont have any ecm modifications the best thing to do is have an egr valve on the car that is functioning properly. I just replaced mine last week and noticed an increase in power due to the fact that my old one was sticking. So, in short gg250cc, my opinion is either put a new valve in it because there could be more wrong with it than just plugged ports, or if you can get the ecm remapped to work without it then toss the stupid thing, but I personally would advise against tossing it without doing anything else.

Phil

[lcdyal]

slipnfall is correct about the egr. It recirculates exhaust gasses back into the intake stream. The other valve that introduces fresh air into the exhaust is the AIV. It's a black box looking thing with hoses running out of it thats in the engine bay directly beside the exhaust manifold. I personally removed the EGR and AIV on my 91 240, I had my head ported and polished and I did not want dirty exhaust getting back into the head. I didnt notice a difference in hp and I dont have to worry about emissions here in S. Ga. Do not remove the emissions system if your state requires emissions testing. If you do decide to remove it, remember to cap or re-route all loose vacuum lines, plate over the egr hole on the intake, and cut and crimp the egr feed on the exhaust manifold completely shut.

[slipnfall]

If you just remove the egr valve and dont change the calibration to compensate for this you will end up with a lean running engine ...

Thanks for the added note - I did know of/consider this condition. I'm assuming this is something JWT can retune for? How much of a decrease in fuel injection are we talking about when the EGR is activated? This is something I'm curious to learn more about, since I really don't need the EGR in my county.

Don't mean to hijack the thread.

-Jamie

[marshun]

removing the egr makes the car run lean huh? is this one of those chart proven things? or theory?

[slipnfall]

Quote »- I did know of/consider this condition.[/quote] Sorry, that should have read: 'I DIDN"T know of/consider this condition.'

Marshan, I myself am not convinced that the ECU does that (alter the fuel delivery durring EGR operation). I believe what the last poster meant was 'when the EGR is activated(wether it's physically there or not), the ECU leans the A/F mix'. If this is the case, then it will only lean when the EGR is activated(or tries to be).

I suppose I can understand why it would. If the exhaust gas can not be reburned, then no fuel should be added to accompany it. This exhaust however does takes up space in the combustion chamber, leaving less room for burnable oxygen. Thus less fuel should be added.

If the ECU adjusts the A/F when it 'activates' the EGR, then I don't see any way around this(other than a retune). On the other hand, if the ECU adjusts A/F based on the EGR switch mounted on top, this could be bypassed(trick the ECU into thinking it is never opened - so never adj A/F). I'm assuming though this switch is used to verify EGR operation(throw code otherwise).

<shrug> Just my thoughts. I think this thread could use some authoritive clarification. Anyone?

[pmkls2]

Well, there are a few things to take into consideration here. First there are different methods for egr valve actuation. I am really not familiar with a KA24DE egr system, mine is just a KA24E. On setups like what is on my car that are only vaccum controlled the computer has no clue when the egr valve is open or not as it doesnt control the operation of the valve. The engineers design the valve to come on under certain conditions (cruising at light to medium load mainly). They know when the valve is supposed to be open and they program the ecu to lean out the fuel curve (keep in mind that these are very small variations) during these certain conditions. Now, electronically controlled egr valve systems do operate a little different. When the ecm commands the valve open it also leans out the fuel curve. Now when it does this it will notice (via the o2 sensor) that the engine is now running too lean and it will turn on the CEL and set an egr code. Now on with the rest of the stuff. ALL computer controlled vehicles can adjust the fuel trim a little, that is the main role of the o2 sensor so that the ecm can keep the air:fuel ratio correct (obd2 vehicles have much stricter tolerances to stick to for emissions purposes). However in order for the ecm to compensate for the lean mixture first it must see the lean mixture condition present. And that means????? Well it means that until the o2 sensor sends a lean signal to the ecm and the ecm adjusts injector pulse the engine will be running lean during this time period. So, to be much more precise here with my answer the main problem that you will run into here wouldnt necessarily be the threat of permanent engine damage ( it is possible but unlikely). But you are actually cancelling out the benefits of not having the egr valve if you dont have an ecm that is programmed to work without it.Y ou are going to have an ecm that is constantly adjusting the fuel curve so it will not be a consistent fuel mixture which pretty much is going to be robbing you of power and not adding ( you prabably cant feel this but it is there)Trust me guys there are 2 reasons that I would LOVE to toss my egr valve. The first being that I dont like em because they are just a nuissance that is only there to satisfy the tree-huggers out there. Second I dont like spending the money on the upkeep of said tree-hugger-satisfying device. I hope this clarifies things a little more for ya, if not just e-mail me as I dont always come to this forum.

Phil

[pmkls2]

by the way the e-mail address is [email protected]

[lcdyal]

All of my emissions have been removed for quite some time. And I've never noticed a difference in power between before and after removal. I havent even had any occurences of my check engine light coming on. So as I was saying earlier, If you dont have to worry about smog testing, snatch that s**t out of there. It makes working on the rest of the motor a little easier without all the vacuum lines and other junk in the way.:ylsuper

[Thee 240sx Owner]

I took my egr valve off my ka24e and never had any problems... capped both ends and never once ran lean... and btw who ever said the egr was the black box next to the exhuast needs to get an fsm manual and stop assuming things... That circulates air into the exhaust to help in dispating smog before the cat

[pr240sx]

The EGR has no ECU effect whatsoever.

The ECU can and will compensate for the removal of the valve

The O2 will compensate for that and in open loop the ECU will use its pre-defined maps. As ofr closed loop, the O2 sensor will be checking for rich/lean and the ECU will adjust accordingly.

This is AT least on theory.... in practice...usually will work with no problem unless you have an OBD whatever number car or a California S-13

[lcdyal]

Yo RacinDa240sx,If you'll go back and read a little more critically on the post about the black box beside the exhaust manifold, I said it was the AIV not the EGR. And I know perfectly well what it does. I took all things into consideration before removing mine. So the only assuming that has been done was by yourself. Oh, and btw I do own a fsm and I am very farmiliar with it. Thanks for the misinterpretation.

lc

[RatedR]

Just to ask, how would one go about capping off the EGR????

[Thee 240sx Owner]

go to discount and ask about their "Help" products. they have a set of end caps made out of some thick rubber that fits perfectly over the ends of the pipe... just cut the pipe in half and cap the ends... and use hose clamps to keep it from popping off

[im two techno]

Don’t do this with ODB2 96 or newer the car will sometimes die on deceleration. The old OBD 1 ECU are no big deal.

OBD2 really is advanced i so wish i could tune with it.

Damn politics!

[240aholic]

What about the other valve that recerculates exhaust gas back into the air box?(valve is right by exhaust manifold) what is that called and can you remove it?