Hi board,
Failed smog test. High Nox.
I suspect the egr system is not performing properly. The system is not clogged, and the egr valve and the vacuum solenoid operate ok. However here is what happens(hot engine) when I attach a vacuum guage and listen to the solenoid with a stethoscope: when I rev the engine I here click, click, click, click, clicking, and I also get a good vacuum reading on the guage. I get this response only when I first rev the engine. If I hold the rpms anywhere above idle the valve stops clicking and the vacuum goes to 0. Ive done wiring continuity check from the ignition computer to the solenoid,and tested the solenoid per the bently manual, ok.

My only other thought is that its not the egr at all, that possibly there is some great digital pubah that has gone entirely over my head, and hence Im here trying to hit a homerun in a dark ball park.

Any help is greatly appreciated.