I am wondering how to nail down an internal vacuum leak in a 2.0 lsj ? Having some issues with the car and it was suggested I may have an internal vacuum leak..

 

Noone ever had an internal vacuum leak on a cobalt before?

 

what do you mean internal...only vacuum hose go from
Lower intake to BPV, from there to blower

also brake booster and EVAP hoses

what is it doing?

its possible the supercharger or lower intake gaskets are bad also but no info in your posts tell me you have no clue either

 

Exactly -- no clue lol . Had it at the shop for rough idle a week ago and he couldn't find an issue and said could be an internal vacuum leak , I was wondering if that would mean what you said , gaskets.

 

rough idle could be injectors/MAF/Dirty TB/plugs/EVAP solenoid...

what is the whole story, give us details or we can not help you