To Stocker 89:
I was way too hard on you, and I apologize for that. I have to quit posting at 4:00 a.m. If the EGR is open at idle ,you will have a vacuum leak. Also on a MAF car any air that enters past the MAF is a vacuum leak and will not be accounted for. So a leak in the PVC fresh air system or the EGR will be air that is entering the engine without the proper amount of fuel to go with it. This causes a lean condition. Even a very small leak almost can cause cold start dying , idle problems and stalling.
Years ago I had carbon chunks sticking my 83 T-Birds EGR open. You would be driving down the highway and everything would be working great. Then I would pull off and the car would die at the exit of the off ramp. I would have to drive with two feet at stop signs until I got home. Then Pull the EGR and clean it. The intake was carboned up because the previous owner had bad O2s and the car ran rich for quite some time. I changed the O2s and it started burning that carbon out right into the EGR.
The EGR opens on part throttle conditions. It doesn’t not open at idle or during WOT. Don't take my word on that do some research. If you can find information different post it, and we all will learn something.
Having the EGR disconnected will throw a code. The timing will be affected as well. How did you block off the EGR? With the non-egr car's block off plate or did you leave it connected? If it's still on the car are you sure it's closed? Did you disconnect the EGR vacuum line from the EGR solenoid? If your EGR is partially open you will have a vacuum leak. They get carboned up and don't seat. You can get a new one from $50-$100 at Carquest. There is no performance lost with a EGR as it's closed at WOT. The only reason I would delete it on my car is because it's a pain in the *** to remove when pulling the blower.
There are three components to the EGR:
1: EGR solenoid which is just a solenoid valve that pulses open and close via the EEC to apply vacuum to the EGR diaphragm. This has a built in vent so that the diaphragm can vent and allow the EGR to close. If the vent and screen are damaged you can get a small vacuum leak from this part. I had this happen on my 89 SC and in cold weather 30 degrees and colder the car would die as soon as it would start. After about 15 seconds of running everything would be fine. When I pulled the solenoid valve the vent and top were missing. $30 later the part was replaced and no more problems for the last 2 years.
2. EGR PFE which is a backpressure sensor that measures exhaust backpressure via a gray silicone hose running the EGR exhaust tube. When the EGR opens the back pressure drops and the amount is sent to the EEC and by this it determines how open the EGR is.
3. EGR valve which is just a valve that is operated by vacuum diaphragm. It's very simple and the design the SC uses is much better at not clogging up than earlier design IMHO.
If you want to remove the EGR, remove it and block off the port with a plate. Then get a EEC tuner or get a chip burned with the EGR turned off inside the programming.
What David Neibert is saying makes a lot of sense. If the valves are not opening and closing at the right times vacuum wont be correct.
Jerry