fixed boost leak, now lower vacuum as a result?

[BoostedG20]

Found a boost leak when pressure testing today from a bolt on my turbo outlet elbow pipe, sealed it and started her up. Two things happened...my idle at vacuum dropped from -22inHg to -17inHg and my a/f on the wideband at idle went from 14.6 to 16.8.

Just looking for some causes of this to occur...I don't see how fixing a boost leak would reduce vacuum. It would make sense why a/f would go up, but while in vacuum at idle? Definitely confused here!

[hobbs]

If you're having a lean condition at idle you have a vacuum leak somewhere, is it running rough at all? What did you pressure test the system to when you were doing the boost leak test? How are your AFRs under boost?

My guess is that when doing the boost leak test you created a new leak, either a bad gasket(TB, IACV, ARV) or you tore a vacuum line open. You do have to remember how old these cars are, the gaskets and rubber hoses start to get dried out and crack causing all sorts of issues.

[BoostedG20]

afr under boost has dropped now that I've been able to do some WOT tests...sounds like I need to start spraying throttle body cleaner around the engine to listen for revs to climb, or is there an easier way to check for vac leaks I don't know about?

[hobbs]

Lean in vacuum and rich under boost... you has a leak somewhere. Easiest way is using a smoke machine, easy and simple.