EGR function

[Edmond]

I know that the EGR valve plays a role in emissions; but in the big picture of the whole emissions package like a good tune up, cats, pcv and all that good stuff, how much does the EGR matter?

Can a faulty EGR cause an irregular and funny idle?

 

[vader86]

Its primary function is to reduce NOx in the emissions by reinserting the exhaust gas back into the combustion chamber where its burned. Its a minor add-on, more for the CARB requirements, and it has been removed in the new Corvettes. I dont think LT4 had it either.

It can be a cause of surging idle, but in my experience that happens more with the old Silverado trucks of the mid 90s.

 

[taegdh]

You bet it will cause a surging and uneven idle. I've replaced mine and cleaned everything associated with it. Took the better portion of a morning, including breaks for coffee, bugs bunny and the road runner.

But also on vehicles like mine and yours, (greater than 10 years of age), even with low miles time and weather may cause a minute leak in one of the vacuum lines. I'd paint them with a little soap and water and if things smooth out, you've found a leaker and that may also be a culprit.

Did you pull the codes to come up wit the EGR? Most of the older computers are / were overly sensitive and would pickup the EGR out of wack. The worst part is I've seen EGR go out of spec by just running over a rough rail crossing.

As stated previously, I don't think they are on anything after 1990 or 1991.