I need some help to understand the purpose and operation of the EGR system in my van. I did a little research and from what I read it seems the EGR opens to allow exhaust gas to enter the intake manifold, which for one, is supposed to reduce the emission of a particular pollutant, I forget which one. Another effect of introducing exhaust gas is that it reduces the ignition temperature of the fuel combustion in the cylinders. (I guess this is because it reduces the amount of oxygen available for combustion.) This is supposed to reduce pre-ignition and knock, but I'm not sure if there is anything else that might be accomplished by doing that.
So the question is:
What effect if any does this have on fuel economy? In other words, does recirculating the exhaust gas improve or decrease fuel economy?

Thanks for any input.

 

I've always heard the EGR system was for pollution reduction, not any kind of fuel economy gain. (I have a 96 E-350 too, and will be watching for answers...)

 

I am trying to get this information to determine if I can disable the EGR while I try to track down an intermittent problem. I went through a batch of tests and I am at the point of monitoring in-use parameters. I tee'd a vacuum gauge off the vacuum line to the EGR Valve and mounted it on hood so I can monitor the vacuum while I am driving. It seems to work fine as I can see the vac rise to near 5in mercury of vacuum when I accelerate. The problem is that sometimes, when I start the engine, the EGR valve opens, which it is not supposed to do. Something is causing the vacuum to be applied to the EGR valve when I start it, I can see the vacuum rise on the gauge when the issue occurs. I know the valve isn't sticking open when I turn the engine off because there is no vacuum showing on the gauge, and the idle is OK. If the valve was sticking open during that pre-shutdown idle it would cough, sputter, and stall, as it does intermittently when I start the engine.
So, while I am trying to figure this out I'd like to just disable the EGR (pop the vac line off of it and plug it with something) if it doesn't harm the engine or kill my gas mileage.
What do you think?

 

EGR does improve fuel economy as a side effect of reducing combustion temps.. that allows the engine to tolerate a little more ignition advance. All of the benefits of EGR are very small and not something you would notice from the drivers seat, to give you an idea engineers have designed out the need for it on newer engines with changes to cam timing and improvements to fuel injection timing and control.

 

The thing that controls vacuum to the EGR is the EVR(EGR Vacuum Regulator), these things sometimes fail so it would be worthwhile to change it... they're not expensive.

You can temporarilly disable the EGR but it will set codes and possibly the check engine light.

 

[QUOTE=Conanski;15274211]The thing that controls vacuum to the EGR is the EVR(EGR Vacuum Regulator), these things sometimes fail so it would be worthwhile to change it... they're not expensive.

I can't find a Vacuum Regulator by that name on this van but there is a an EGR Solenoid and the note next to it says "Regulates amount of vacuum applied to EGR Valve". I think that is the same device by a different name? If it's not expensive I think I'll try to find one and replace it.
Also there is a an AIRD Solenoid and I'm not sure what that does. It's right next to the other solenoid, it's description says, "Directs secondary air to the exhaust manifold or bypasses into the atmosphere."
FYI, I was able to contact an old mechanic I used for years, and he told me in no uncertain terms... "F that EGR system, pull the tube, cap it and forget it!)
Thanks for the advice.