I've got a 1991 F250 with the 300 6. My EGR is messed up in a bunch of ways. The tube is rusted through and the nipple is no longer on the exhaust (no place to attach it) so it draws fresh air vs. exhaust if and when it is open. I'm also getting code 558 (also I have codes 212 and 452 which may be adding to the current lack of power?) so I think the solenoid is shot as well. With the EGR hooked up and engine warm, I get a random but frequent miss under load and the truck doesn't really want to get much above 50mph.

All that said, the truck runs better with the EGR unplugged and the vacuum line blocked. Of course, my check engine light is on all the time.

So here's my questions;
1) If the EGR is disabled and the computer knows it (CEL is on) what will that do to timing?
2) If I put one of those plugs on it to fool the computer THEN what will happen to timing when the computer thinks it's open?
3) If I just disable the EGR and leave the check engine light on should I advance or retard the timing?
4) If I remove the EGR and get a plug to fool the computer should I advance or retard the timing?

NOTE: I'm not trying to make something special out of the truck, it's just a load hauler around town and the farm. Mostly I'd just like it to not miss, have reasonable power under load, and drive at 55 mph if I need to without doing something that's going to damage the engine.

 

Does the valve move if you apply vacuum to it? Are the vacuum lines good? You could place a piece of metal from a soda can between the EGR valve and the intake manifold. EEC-IV does not know if there is flow through the valve; only that vacuum was applied and the valve moved to allow EGR flow. You need to leave the sensor connected or it will set off the check engine light. You could still get a check engine light using one of those plugs to fool the computer.

 

Yes, the valve moves if under vacuum. I'm thinking about doing just what you suggest; blocking off the EGR at the intake. I'll also add an edit to my original post because I've also got a couple other codes.

 

Soda/beer can block for now. I use this: manifold/gasket/can/gasket/valve.

Mine was leaking and smog exempt anyway

 

When you did the beer can delete, did you adjust timing? Any problems with pinging or power?