Missing vacuum line
 

Recently I replaced the upper and lower intake gaskets and upper manifold on my 97 park ave.
I seem to be missing the vacuum line that goes to the back of the upper manifold on the same fitting as the brake booster hose.
I have replaced the lines from the TB and FPR as they were damaged when I removed them to do the manifold and the car would not start until I fixed that leak.
Now I am getting poor mileage and CEL has been going on and off.
Also the fitting that the brake booster hose fits on is just sucking in outside air from that little T, Which I'm sure is not good.

Here is a photo.

Yup, your correct. That missing vac line is more than likely the line that goes to your HVAC control head inside your car. This is the knob that controls what ducts the air comes out of. When the HVAC looses vac, it should default to the windshield defrost position.

Now, if your Park Ave is anything like my Bonneville, look for a large loom of wire. It's probably that one in the picture you posted. Inside is a plastic tube that probably popped off while you were working on the other lines and it probably just pulled itself back in. Worst case scenario should you not find it is, cap off that port with something. This will prevent a vacuum leak and allow your engine to run better.

Yeah, I could not find the line in the wire loom. I tried plugging this hole immediately with my finger upon finding it which killed the motor, so that is not an option. I will try looking again tomorrow for that vacuum line when it is light out and not freezing rain.

Turn the engine off, then plug the port. What you did was temporarily confused the PCM and you actually stalled it. Try it again.

Moving the info from the other thread here.
Here is my reply from the other thread.

It comes out of the brake booster pictured in my previous post, and runs into the big part of the wiring harness in that area, where it runs inside the wire loom till it comes around to the front right, where the EVAP Canister is.
I'd inspect all of your soft EVAP lines/connectors, and replace them if they are dry-rotting, the hose is not that expensive at any auto-parts store, I found almost every soft EVAP line/connector I had were starting to dry-rot, if you have self leveling struts, then even the soft hose under the right rear of the car, that runs to and from the T connecting to the air compressor, if you get under there and look at it, you may want to check/replace the soft EVAP line that runs to the fuel tank, it is tough to reach, but if you have long arms it is easy to remove that soft part of the EVAP line, the line I am referring to runs alongside the fuel delivery and return lines.

If you cannot find it the soft hose may have fell off, there should be a small plastic nipple from a plastic line inside the loom. I tried to follow mine, and it seemed to follow the loom from that area to the back left of the engine bay, where it made its way towards the passenger side front, it ran alongside under the bumper area, then connected to something on the front right driver side, around where the EVAP Purge Canister was, I could be wrong though, I will try to retrace that line tomorrow when it is daylight.


Here is that pic of it that I posted in the other thread.
https://www.gmforum.com/attachments/...evap-jpg?stc=1

Ok, plugged it. Running good. I will turn the CEL off in the morning and run it to work.
Thanks Mike.

Ok, thanks again William. I would like to replace the line that was once there so that would be very helpful if you could take a look for me. I think this is a good temporary fix though.

Ran to and from work today with no issues and the light turned itself off.

Glad to hear the light went off, I was not able to inspect where that line goes today, but I'll try to look at it later today, that way you can re-run a new EVAP line to wherever it connects.