Originally Posted by mr300ce

Here's a secret "they" don't want you to know about testing the mechanical part of the EGR system. ....

1. Locate it on the engine

2. disconnect the vacuum line on it

3. attach one of your own

4. with your mouth, suck on vacuum line firmly. A good valve's diaphram will hold vacuum. If air keeps coming in, (like a straw) then the valve is bad. = replace valve

5. if valve seems good, start engine and let idle. Apply vacuum again. Engine RPM should drop because you are allowing exhaust gas into the fuel mixture at the wrong time.

This system is working properly. Do it several times to learn how it effects idle, and to feel good that you did it yourself.

6. if engine RPM does not drop , then the tubing and/or ports are likely plugged with gunky egr goo, and won't allow flow.