Emissions / EGR System

[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.

[cadillac_tech]

The passages are ok if the eng bogged. Get a helper for a quick test. Have your helper brake torque the engine while your fingers are under the valve(about 1/3 throttle). The valve should lift up. If not, pull the vacuum hose and see if it has vacuum during brake torque. If not, check for manifold vacuum to the solenoid. These are the first and quickest checks to make. If the valve opens on the first check and the engine bogs at idle like you said, your NOx problem is elswhere.