EGR Valve not opening

A.K.A L03 pingy at part throttle, pt2.

I am pretty sure this is my problem and and always has been.

I have tested the EGR valve on my 305 by hooking the hose directly to the valve, bypassing the solenoid. It idles great even with all 15 plus pound of vacuum on it. It should open.

I can feel a slight fluttering of the diaphragm when I place my finger on it, but nothing more than a few thousandths of motion. I didn't think anything of it at the time, but all three of the valves I have purchased have done this. I made sure to buy different EGR's from various aftermarket companies, different model numbers, just to see.

I know I cannot get a Delco unit new anymore, so to all of you, I ask, is there a reputable aftermarket that you have had good luck with?

Or maybe a parts house you know of with NOS factory Delco units stockpiled that you trust?

It would be more likely that your knock sensor is not working. The EGR only works when you are steady state highway driving, to reduce emissions.

Fred Kiehl wrote:

It would be more likely that your knock sensor is not working. The EGR only works when you are steady state highway driving, to reduce emissions.

I know what you are saying, but I bypassed the engine management systems and hooked the EGR up direct to the full vacuum. I even tee'd off a line from the brake booster feed straight to the EGR with no change.

I'm on my second replacement knock sensor. It does work fine, it pulls timing and sets of a CEL if I run 87 gas, that's why I am of the persuasion that the EGR's I have been buying have been the wrong ones.

To check an EGR valve one just has to start the engine and let it idle. Put your fingers on the diaphram and give it a squeeze. The engine should stumble.

Yes, it stumbles when manipulated, so the passage is fine, But vacuum has very little effect on the mechanism.

Another test is to pull the hose off, squeeze the diaphragm in the whole way and put a finger over the port on it. The diaphragm should stay retracted, if not replace the valve.

I am guessing the car must be off for this test?
That is a very useful test, one I haven't tried yet. That would only work on a negative bp valve, right? Which is what my car probably needs.

Yes, car off. If the valve holds you'd have to look at either a vac leak or possible bad solenoid

Ok and the results are in-
No, it does not stay open.
I was feeling a little adventurous so I applied some vacuum via mouth, it feels kinda like a cheap straw with a hole in it.

So where do I find something that will work?

Autozone etc will carry it, I usually order from rockauto if I don't need it right now