Clogged EGR Valve FE effect?

[Rower4VT]

Does anyone have any idea if a partially clogged EGR valve could cause lower FE? My Vigor has almost 200k miles on it so I figure the EGR is atleast partially clogged, though it's not throwing a code yet. Thanks for any input.

[VetteOwner]

yes they can cause crappy engine performace and affect mpg. my trucks was partialyl clogged and i removed it, instantly gained 2 mpg and ran alot smoother

[kamesama980]

yes, it can.

[maxxgraphix]

Only if it's stuck open will your performance decrease. Typically when disconnected your get better FE and power. An EGR is only a crappy EPA device to choke your combustion chamber with exhaust gases to lower the combustion temp. Keeping the combustion temp below a certain point reduces NOx gases. NOx is thought to cause smog.

[StorminMatt]

In other words, the best thing to do is make a plate of metal to sandwich between the EGR valve and the intake manifold in order to improve HP and fuel economy. This way, if you have a car where the ECU senses EGR lift (ie Civic VX), then you cut off the EGR without the ECU throwing a code.

[Rower4VT]

Guess I don't understand how blocking off the EGR won't throw a code. On my vehicle, if the EGR gets clogged up too much it will throw a code. Some of you are saying that blocking it off nets better FE while others say that a clogged(blocked off) EGR decreases FE. Usually I'm pretty knowledgable on engine systems, and I understand what the EGR does, I'm just not sure it's effect on FE. Any clarification, or actually results from blocking it off would be hugely appreciated. Thanks!

[VetteOwner]

prolly depends on the engine on my truck and car both are chevys and the trucks i took completely off and made a plate. it does throw a code once the truck is up to temp and there is a way to program the computer to not even sense or try to sense for the egr. BUT you need a programmer...like i said before, i could get no better than 25mpg. i could interstate drive it , highway, city never went from 25. took off the valve and very next tank went to 27 mpg. now it regularly get around there.

the chevettes, i dunno whats up with that one, it moves freely BUT i conencted it and it ran like crap. idled fine but anyhtign above idle made it studder and fall on its face. so i bought the vacum lien caps and plugged off the carb line going to it and the egr. got 30 mpg in the dead of winter and driving on and thru snow last tank :P

[kamesama980]

^^exactly. depends on the engine. older ECUs won't notice EGR or not. newer ones will. the exact effect depends on the engine and setup.

a side effect that *can* improve mileage with EGR is the lower amount of O2 in the charge means you need to open the throttle more. once the ECU has adapted to the new throttle/fuel ratio you'll end up with less throttling losses. but again, it depends on the engine. other engines, as mentioned, see much better mileage without the EGR hooked up.

[StorminMatt]

I guess I never thought about throttling losses. But it DOES seem like having EGR would tend to reduce thottling losses, since the cylinder pressure could be higher during the intake stroke (thus reducing the power losses associated with the pistons having to overcome atmospheric pressure). But I would tend to think that EGR would REDUCE efficiency at higher power levels. And I am not sure whether EGR is typically cut off in such situations.

[SCoupe]

My 92 VX has 215000 miles so I'd bet my EGR Ports are getting to a point of being clogged. Probably like the one in this thread:

http://www.gassavers.org/showthread....ight=egr+clean

I was thinking that it might be worth buying a cheap oem used intake manifold and taking my time to thoroughly clean the internals and just swap out my old one for the cleaned one.

If this makes sense, what intake manifold(s) are completely VX compatible (ei: 92-95 DX/LX non-VTEC 1.5L D15B7 or the EX D16z6 ?