noise from engine bay

[Stig]

Hi folks,

not been around for a while as I've been a bit too busy at home

I took the cam out yesterday and it seems to have developed a high pitched whistling noise thats cooming from around the injection area.

I believe its a leak on the vacuum side but can't find it.

Anyone any ideas on what to check, how to check it. What can I spray around under there to identify where its a problem

thanks for the help in advance
cheers
Paul