No vacuum at P port at idle, but vacuum and boost while driving - what's up?

[Gremo87]

So I've been working on a low vacuum issue, and I just read that the P port on the TB is supposed to have vacuum at idle - but mine doesn't. My boost gauge used to be hooked up there, and it would see vacuum and boost while driving, but nothing at idle. (I moved it to another source because of this)

I've read maaany people saying it should see vacuum at idle - including at least 1 "Wiseman."

I've read that it can be clogged, but if I can see vacuum and boost while driving, I wouldn't think that's the case....



Anyone know what the deal could be here? It might be completely unrelated to my low vacuum issue, but it just concerned me.

Edit to add: Just found this guy (http://chicago3s.proboards.com/thread/146/1g-mods-free) saying that the P port only sees vacuum on 90-92's....

 

[97 eclenger]

the p port only sees pressure when the butterfly is open. the p is for pressure. so it'll only see any type of pressure after that. someone said the a port should read both. but most people just T into the vacuum line from fpr and intake manifold. people put the boost gauge and map sensors there

 

[Gremo87]

Ahh, ok - thanks. I already moved my gauge line to another source but just wanted to make sure there wasn't a problem with my TB or P port.