Re: EGR Valve, Do i need it
Very true -- EGR is non functional at idle - and at wide open throttle.
The only real way to find out how it's going to affect your engine, no matter what year, is try it! You quite possibly will get an increase in power - EGR does rob power -- usually.
Smog testing -- different states -- and different countries obviously have different rules. Many places do not use a dyno for smog testing -- and NOx emissions only occur when the engine is loaded, so a dyno must be used to create it so it can be tested.
Many places have laws that make it illegal to remove or change emissions equipment - usually visual inspection finds that. Some have the law in place but don't enforce it. Some only test the emissions with the hood closed -- if it fails the emissions test, the hood gets opened to see why - then you get failed if anything is missing or disconnected.
So many different ways!!!
Most of the time to disable an EGR valve it only entails removing the vacuum line to it. Unless the valve itself is stuck open or it's defective, the "no vacuum" condition is it's closed.
If the engine pings after disconnecting the EGR valve when it didn't before, you have one that needs it. You may be able to set timing down a little lower, or use a higher octane gas to stop the ping - both are worth a try.
I suggest if you do disable the EGR, just plug the line, do not discard the controls for it - like temperature valves, relays etc. Just plug the line. Someday the greenies will get the laws changed - you'll need it someday. Then if everything's still there, just plug the line in again. "Ooops, I'm sorry, I was experimenting one day and forgot to put it back."
For the techies -- NOx forms at a "magic" temperature around 3000 degrees and under pressure (combustion pressure.) What happens is Nitrogen "welds" to Oxygen, forming 13 different variations of Nitrous Oxides. The oxides are corrosive and highly reactive - easily combine with lots of elements, several form smog. Deadly to breathe. Under load there's lots of pressure and heat, enought to drive it over that "magic" temp.
After discovery they found that if they spaced the molecules apart slightly with Helium it dropped NOx emissions considerably. But Helium is expensive. They needed an inert gas to space the molecules apart slighly.
Exhaust gas is semi inert for that purpose - supposedly it has very little oxygen and no fuel - if it already burned properly. Adding just a tad of exhaust was cheap and easy. Thus - Exhaust Gas Recirculation.
Very late model engines have some EGR built into the cam's overlap and design of the combustion chambers - but they can't have too much of it or idle gets bad from mifire.