E.G.R. Disconected

Only In A Jeep XJ · Jul 13, 2006

I am in the process of stroking the 4.0 in my XJ. When I get it all back together I'm not puting the E.G.R. back. If i remove the Vacume switch for it from the fender will it throw a code on the computer or do I need to figure a way to hook it back in to the new manifold?

5-90 · Jul 13, 2006

If you have an EGR valve, you have the RENIX system, and the system does not "store" or "throw" codes (being pre-OBD.) EGR was deleted with the introduction of the ChryCo HO electronics in 1991.

The engine will run fine without the EGR valve connected - I usually have mine disconnected, except when I go to smog every other year (damn...) You'll want to leave the valve in place, so it blocks the holes, but you don't need to hook up the vacuum lines if you don't want the thing to work. Make sure you cap off the vacuum lines going into or coming from the solenoid on the driver's fenderwell, so you don't get vacuum leaks.

5-90

HotChiliRam · Jul 14, 2006

What's the benefit of havong the EGR disconnected???

5-90 · Jul 14, 2006

HotChiliRam said:
What's the benefit of havong the EGR disconnected???

Well, it will keep your intake nice and clean.

The "purpose" of the EGR valve is to redirect a metered amount of exhaust gasses into the intake stream to help reduce combustion chamber temperatures, which reduced NOx emissions (at the cost of somewhat increased HC and CO.) Eliminating the EGR will decreased HC and CO (which results from more efficient and compleat combustion of fuel) and a slight (in our case) increase in NOx emissions.

How do I know? Because I took my 87 to the Smog Nazis once upon a time, and failed. I didn't fail because of emissions (all of which were damn near ZERO,) I failed because he unplugged the EGR and tested it with a vacuum pump - and it didn't work.

I honestly don't understand why I'd failed - since my emissions were lower than most cars ten years newer. It proved to me that the EGR system is of limited utility (it was deleted in 1991, remember?) and there's no reason to have it in the first place. The AMC 242 runs "low and slow" enough for fuel to burn efficiently, which is why we "can" get such good mileage out of the thing (until you do gears, tyres, &c. Even then, it's better than nearly any Suburban, Expedition, Mountaineer, or other large SUV.)

It's important to remember that California came up with the idea of the EGR valve, just like California came up with OBD - and both are of dubious utility in reducing emissions. I say, get out of my way and let me tune my engine to run the way I want it to. I'll get more power (due to more efficient combustion,) better economy (due to more efficient combustion,) and reduced emissions (due to more efficient combustion.) Tuning and engine for peak performance is not incompatible with reducing emissions - the two actually go hand in hand, if you know what you're about...

5-90

Matthew Currie · Jul 14, 2006

5-90 said:
Well, it will keep your intake nice and clean.

The "purpose" of the EGR valve is to redirect a metered amount of exhaust gasses into the intake stream to help reduce combustion chamber temperatures, which reduced NOx emissions (at the cost of somewhat increased HC and CO.) Eliminating the EGR will decreased HC and CO (which results from more efficient and compleat combustion of fuel) and a slight (in our case) increase in NOx emissions.

How do I know? Because I took my 87 to the Smog Nazis once upon a time, and failed. I didn't fail because of emissions (all of which were damn near ZERO,) I failed because he unplugged the EGR and tested it with a vacuum pump - and it didn't work.

I honestly don't understand why I'd failed - since my emissions were lower than most cars ten years newer. It proved to me that the EGR system is of limited utility (it was deleted in 1991, remember?) and there's no reason to have it in the first place. The AMC 242 runs "low and slow" enough for fuel to burn efficiently, which is why we "can" get such good mileage out of the thing (until you do gears, tyres, &c. Even then, it's better than nearly any Suburban, Expedition, Mountaineer, or other large SUV.)

It's important to remember that California came up with the idea of the EGR valve, just like California came up with OBD - and both are of dubious utility in reducing emissions. I say, get out of my way and let me tune my engine to run the way I want it to. I'll get more power (due to more efficient combustion,) better economy (due to more efficient combustion,) and reduced emissions (due to more efficient combustion.) Tuning and engine for peak performance is not incompatible with reducing emissions - the two actually go hand in hand, if you know what you're about...

5-90

The irony of the above is that if it was an 87 wioth the original one-piece EGR, it probably WAS working! The 87 had a backpressure valve in the diaphragm, so that the diaphragm would purposely leak until exhaust backpressure built up. They changed the design later, sometime in 88 I think. A good EGR of the first type would never pass a vacuum pump test.

In response to the original question, I think the best option if you're going to run without the EGR is to plug or crimp off its vacuum line rather than disconnecting the solenoid, because the solenoid also controls evaporative canister purging. I don't even know how important that function is, but figure that it's better to leave it alone if possible.

Only In A Jeep XJ · Jul 14, 2006

I guess i frased it all wrong in my origonal post. I'm going with the newer manifolds on my stroker and there is a vacuum switch on the drive fender that operates the E.G.R. valve. If i remove this completely will it cause a check engine? Does it moniter a vacuum signal from the manifoldand need to still be hook to the manifold? Does it need to stay hooked in the harness but not hooked to the manifold? Which do I need to do?

Matthew Currie · Jul 14, 2006

Only In A Jeep XJ said:
I guess i frased it all wrong in my origonal post. I'm going with the newer manifolds on my stroker and there is a vacuum switch on the drive fender that operates the E.G.R. valve. If i remove this completely will it cause a check engine? Does it moniter a vacuum signal from the manifoldand need to still be hook to the manifold? Does it need to stay hooked in the harness but not hooked to the manifold? Which do I need to do?

I don't think it monitors anything, but if you have the original evaporative canister setup, you might still want to keep the solenoid alive and connected to that, then just cap the vacuum line that would have gone to the EGR. If you also aren't running the original evap. system, I don't think you'll get any codes or other running issues if you just can the solenoid. However, if there's any doubt, you could leave it on and try running with it unplugged and see if there's any difference. I'm pretty sure there's no feedback to the ECM from that circuit, and it will make no difference.

87manche · Jul 14, 2006

there's no feedback to that circuit. The ECM just triggers the solenoid. If you cap the vacuum line it won't cause any harm, the ECU won't know any different.
Currie is correct, it does control the evap system also, so don't remove it, just remove and cap the vacuum lines that went to the EGR vavle in the manifold.

Only In A Jeep XJ · Jul 16, 2006

Thanh for all the info guess it will be a trial and error thing. Just trying to get rid of all unused items while I have the engine out.

E.G.R. Disconected

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