Been messing around with this stupid car for just about too long. It all started when I noticed my EGR had 2 broke screws and I took it apart to fix. The gasket that you can't get was burnt to dust so I tried about 3 different times and materials to fix it. They all burned up or blew out. So it got me thinking the cat was plugged, fixed that problem, gasket held and the egr was about 5x cooler. Now I get **** poor milage and only 1 code, a code 13 intermittently. (oxy sensor lean while warm engine cruise) Now I can't figure out what else to check. I've checked all the normal stuff, plugs, cap, timing. All seems ok. The only way I can tell anything is wrong is the code, the bad milage, and it can't find an idle. It goes from open loop to closed loop again and again. The oxygen sensor is relatively new but I am going to try replacing it anyway, beyond that

Theoretically if the EGR was stuck wide open would the oxygen sensor read lean and dump more fuel? That would explain poor milage, but there isn't much if any power loss as far as i can tell.

Also if anyone knows how to electrically test the digital egr (ecm side or valve) that'd be great. I read the egr article in vette fever and they talked about the ecm grounding out the solenoid to open the valves, all of the connections are grounded which would = all open, if the article I read is right, for some reason it just didn't seem like they were talking about the same egr.

 

I would start off with replacing the o2. Hm, if the EGR was all the way open it would probably run leaner than normal, but not to the point of causing you to ping or what not. My Jeep ( I like to use that little engine as an example since I know it really well ), it's EGR stays open all the time until you pull the throttle open. Now, when I have the vaccum disconnected on that EGR, I get around 16mpg, with the vaccum going (EGR all the way open during idle), I get around 20-22mpg depending. Yet, I'm not very familiar on the digital EGR setup and how they specifically work on the late 3rd gens. I notice the one on my 89 RS tends to stay closed or move very little when I rev. I'm thinking you should be able to notice it opening at least a bit (for me), but I'm not that certain. Yet, I get good mileage out of it, so I'm not concerned at the moment. *shrug*

-dan