My question is i'm not sure if my egr valve is operating. I definitely have vacuum to it, when revving the engine above idle. The diaphram does not move up when revving the engine. I manually lifted it and the engine did stumble so i assume the passages aren't totally blocked? IF the vacuum is reaching the valve but it won't cause the diaphram to open is the valve itself bad? I would appreciate any help

 

In general, if you have vacuum at the valve and there is no bypass or relief vent in the system the valve would be bad. If you have a hand held vacuum pump you can test it. The diaphram on the valve may have a leak. If the solenoid is before the valve it lets vacuum to the valve or no vacuum to the valve. The old EGR's were simple and worked thru a temp sensing vacuum switch. The newer ones are pretty complicated/involved.

 

It's an 83 with the 307. There is basically no cat (it's hollowed out). Could that cause a sufficient drop in exhaust backpressure that would not allow the egr valve to open. I've read it needs some amount of exhaust backpressure to operate and the regulate how far the diaphram opens

 

with the engine at normal temp. the control solenoid allowed vacuum through. so i think the solenoid itself is ok.

 

Welcome! (There's beginning to be quite a few of us Robs here... )

Solenoid is fine. Sounds like the internal EGR valve port in the shaft may be clogged or the bleed valve stuck open. Remove the valve and you can find out. This is a funky valve...
Here is the manual page describing it - I assume you have the 5.0...


A hollowed out cat could cause it to not have enough pressure, but check out the valve itself, first.

 

Doesn't sound right to me...

I'd just get a new valve - $22.79 at RockAuto.

- Eric

edit: but if Rob says so, then maybe it IS right...

 

Thanks for your help. I had the valve off the manifold a while ago, there was some carbon but it wasn't bad and i cleaned what i could. the diaphram moves but i'm not sure if it should be easier to push open as i don't have a good valve to compare to, even tried going to parts store to compare but no one seemed to have it in stock w/o ordering

 

i was actually looking at rockauto before, there seem to be like 10 different choices. i suppose it would help to write down the numbers stamped on my old valve

 

^^ Well chances are you're not getting an ACDelco at Rock, so don't bother with the part number on the EGR itself.

Really sound like to me that it's broken, unable to open under vacuum, so I say get a new one, or a used one at the junkyard if your planing to removing emissions althogether

 

The valve should squish open pretty easily when pushing it open with both thumbs.
Should feel about the same pressure as it would take to smoosh in a beer can in the center with both thumbs.