First, that mushroom shaped valve on the back of the LT1/4 Intake is the EGR valve, right? It has vacuum lines going into it, right? Pics would be good...

OK, now say you have an LT4 with Hooker LT's, and this valve is still connected to the vacuum line on the drivers side, could this cause a vacuum leak, causing it to idle badly, and there to be the MAP high (code 33, I think?), EGR is disabled in the PCM...

Thanks...

 

Anyone? Am i on the right track, at least?

 

Is the EGR tube disconnected from the back of the intake manifold and left open? If so, yes, this could cause a vacuum leak and a stumble.

You are correct as to what the EGR valve is

 

Well, I don't really know, I felt back there, and couldn't find an empty hole, however, there is no hose from the header to go into it, so there is no intake of exhaust air to "charge" it, and flow into the manifold. The vacuum lines are all still connected, by which I mean the one on the Driver side, it goes from the manifold to this little electronic gizmo to the mushroom shaped valve. I know that is the most technical description I could possibly make, but I have never screwed with EGR stuff before. And if i am not mistaken, there are 2 ports on the back of the manifold itself...One seems to be blocked off, but I am not really sure, as I can't see it.

Would I be better off buying an EGR block off plate, and removing the whole thing, and capping off the nipple on the manifold?

 

First, lets take care of the vacuum line. There is one from the drivers side of the intake manifold, to the EGR "solenoid", on a bracket at the end of the intake manifold. From the solenoid there is another single vacuum line to the EGR valve itself - yes the "mushroom" thingy on the back of the intake. You don't have to do anything to the vacuum lines, as long as they remain connected on both ends. See the picture below. Ignore the vacuum line running from the passenger side of the intake... that has fallen off the fuel pressure regulator in the picture, and is not related to the EGR system.

If you chose to remove the vacuum lines, simply cap the port at the intake manifold with a "vacuum cap".

As far as the supply pipe from the #8 manifold runner to the back of the intake manifold... it goes to the "hole" on the right side of the back of the intake manifold, as shown in the pic below:

Back of intake

That hole can NOT be left open. Get a blanking plate from:

SJM

and cap off the opening. Then you can either leave the EGR valve right where it is, or remove it. If you remove it, you need another blanking plate from SJM.... the 2-piece set.

 

Ok, that helps...I just took off the block off plate they made for the pass side hole, and it is just welded in metal on an EGR plate...They filled in the hole, with what looks like weld materiel. I have no real down time, but i know a place that has these locally, so I'm going to head over there. Would it be wise to replace the valve, too, since I have to get this done today?