I recently cleaned the EGR on my 94 F150. It was stuck solid, not moving up or down. A lot of carbon. Cleaned port, installed new gasket.
My question is. I have seena report on the EGR that says it will open fully at 5Hg. I have a handheld vacuum pump tester. I put the tester on the EGR supply line that comes from the EVR (Electronic Vacuum Regulator ). I get almost exactly 5HG when I increase the throttle. On top of the EGR is the EVP (the EGR Position Sensor). It is a variable resistor, (rheostat), that changes as the EGR opens and closes, light a light dimmer. When I use the actual engine supply, which checks at 5Hg, the position sensor never changes. When I use a handheld Vacuum pump and apply 1 thru 5Hg, the valve moves and causes the EVP to transition through its resistive range. I am using the actual hose from the EVR, which gives me 5Hg with the tester, yet it will not open the valve. Any thoughts?
Thanks.

 

Sounds just like my truck that failed for high nox.

 

I finally got new spark plugs, and that did the trick. I should have started there instead of the other way around. The good news is all of the sensors and vacuum lines and relays that play a part in this got a good going over also. The truck runs smoother that it has in a long time. The check engine light is gone now for 3 weeks. The EGR valve was stuck solid. I think it sticks a little, so it doesn't open up while doing a normal test with the engine vacuum. But once the plugs and rotor were replaced, and the fuel filter, it seems to be working fine. It does use some oil. It doesn't seem to have as much get up and go as it used to, but neither do I.