I was inspecting the AIR and EGR ports on the back of the intake manifold today, and I was always under the impression that they plumbed directly into the main intake plenum, but apparently they don't. It looks like the ports run down underneath the plenum where the PCV valve feeds into. Here's my question: does that area where the PCV valve feeds into see the same atmospheric conditions as the plenum itself, as far as airflow and vacuum are concerned? The idea I have in mind is to relocate all the sensors and vaccum fittings that are plumbed into the main plenum into the AIR/EGR ports on the back of the manifold, in order to have everything "hidden." (The only vaccum ports I'm still utilizing are the MAP, fuel pressure regulator, and power brake ports.)

Does anybody see this as causing any problems? Will it throw off my MAP readings? Will vaccum be sufficient through these ports?

Thanks.

 

There are no AIR connections to the intake manifold, only EGR. There is a port from the point where the riser tube from #8 primary connects, to the hole for the pintle of the EGR valve.

Since you have removed the EGR system, there will only be PCV flow through the passages on the bottom of the manifold. When there is flow, the vacuum at the EGR blockoff plate is going to be less than in the plenum. Appears what you are attemptnig to remove is the Heat/AC vacuum line, the EGR vacuum line (no longer needed) and the Opti vent line (hard to tell, since nowhere in the post do you tell us what year your car is, and the vacuum connections are different for differnt years). What other sensors are you finding connected to the intake? There aren't any.

Why not add a "signature" with basic info about your car, like year.... then clarify exactly what you are trying to remove.

 

Okay...

Forgive me for including AIR with EGR. I'm so used to seeing those two terms mentioned synonymously that it slipped my mind that they work independently from eachother. Forget I said anything about AIR.

My car is a 95, but I've installed a Delteq system and since I've got the motor in pieces at the moment I figured I'd take the opportunity to remove the rotor from the Optispark and seal it up tight for good. Since I've done this, I'm no longer going to use the vaccuum lines that vent it. I have also deleted the entire HVAC system, as well as the EVAP/Purge solenoid so those don't need a vaccuum line. The only things I'm hooking up to the manifold are the brake booster, fuel pressure regulator, and MAP sensor. As far as the PCV valve is concerned, since I've eliminated the vent lines going to the Opti, I'm going to go ahead and convert it back to the 92-94 style setup that used a "U" shaped hose and eliminate the aluminum tube that runs to the port in the front of the intake.

What about this Fred: just chopping the two EGR ports off the back of the manifold altogether? Is this doable without disrupting PCV flow in any way? (New metal would be welded in to make the manifold airtight again of course.) If those ports were cut off and out of the way, I could just drill and tap new holes directly into the rear of the plenum. Would that work?