[mckimjim]

I have an '89 Seville with the 4.5L engine. I am having problems passing the state emissions test. The NOX levels are high, everything else is fine. I have replace the EGR valve and catalitic converter but it made no difference. How can I tell if the EGR valve is functioning (getting vacuum)? I understand that there is a temperature switch and a control module that lets the vacuum operate the valve but I don't know much more.

With the car idling, I reached in underneath the valve and off seated it. The engine started bogging down - I think this would indicate the internal passages are okay?

Thanks in advance.