Secondary use of fuel tank pressure sensor.

Hi

One of Sd:s youtubevideos he told that one can use fuel tank pressure sensor with labscope for diagnostic purposes. 

​​​Does anyone remember what video it was and what was the purpose for the sensor?
​​​​​​(was it intake vacuum?) 


​

Had to do some digging around, but I found it. It's an SD Premium video:

www.scannerdanner.com/scannerdanner-prem...-testing-part-4.html

There's even some details in the comments from other members that have more specific build information.

Thanks.
Video that i saw, wasn't premium. That does not matter, now i know where to find information when i have time to proceed.