Hi to all. New to the forum and lots of good information. My question is, how do you test an EGR valve to know if it is working properly? The engine is a 4.9 out of a 1992 Deville. The engine has a hesitation under light load, and a little bit under steady load. But not at idle. Any ideas?

Jack

 

On the northstar valve, you're supposed to clean it with a carb/choke cleaner and black gunk is supposed to come out. Also the rubber lip on the smaller socket is supposed to pop back out when you push it if it's good. If it doesn't pop then you need a new EGR. This is the northstart though, not the 4.9