1998 Chevy Lumina erg valve

What engine, 3.1 or 3.8 it makes a difference. You have to check for a 5volt reference on the pintle position signal circuit. And the pintle position signal circuit for a short to the EGR valve control circuit. Post back with what you are trying to do and will advise from there.

I might need to start over, was there a code? If so what was it? I need to know what wires your testing, what are you trying to figure out?I need some more info to properly help you. Did you follow what I posted earlyer? Post back and I will help you.

I will try to help as best I can, but I really need the code that set. You need a scan tool to command the egr open/closed. Here are some things to check. Excessive deposits on the EGR valve pintle or seat.

Remove the EGR valve and check for deposits that may interfere with the EGR valve pintle extending completely or cause the pintle to stick.

"Â Poor connections at PCM or EGR valve. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
Inspect the wiring harness for damage. If the wiring appears to be OK, connect J 39200 DMM and check circuit continuity while moving connectors and wiring harnesses related to the EGR valve. A change in the DMM display will indicate the location of the malfunction. Remove the egr and clean the egr tube they get plugged with carbon. These are some things to check, post back with the code so I can give better advise.

No the missfire would not cause the egr code, the problem is the egr tube is plugged with carbon, you need to clean out the egr tube and passage in the intake and this problem will go away. Post back with any other questions.

I would take it off, you can clean it better, and yes you will need another gasket.