Hello all, I decided to clean my engine today and saw a plug looking thing not plugged into anything, so I was just wondering what it was, and if it is supposed to be just hanging there? I apologize in advance if it is a stupid question thank you.

 

I will name him "George".
For real though, it's a vacuum "diode". Only allows for one-way airflow.

 

I like the name George, so I will continue to call it that. Thanks for the quick response. Is he supposed to be plugged into anything? Or does he just sit there?

 

It looks like the vacuum check valve as part of the exhaust system vacuum control system. I can't tell from the pic where exactly it's located but yes it should be connected to another vacuum line. It's only so long so look within the range for an open vacuum line


 

It's a one way vacuum line for testing. It's plugged right after the check valve. I used it for manifold pressure for my HKS Camp2 boost readout. It Y's near the manifold. The other line goes to the fuel pressure regulator.

See post #31 in this thread:
https://www.jaguarforums.com/forum/x...-138621/page2/