While on a wot run today my boost suddenly dropped from my normal 1.9bar to 1.3. I pulled the car over, checked i.c. pipes and the hoses to my forge mbc. All seemed fine. Got home found the nipple on the bottom of the intake pipe was not capped. capped it did did another pull, same deal 1.3bar. Just strange one second everything is fine and the next no boost wtf. I just had a boost leak test last month and had fixed some small leaks. I guess I will make a tester and try another one tomorrow. Anybody got any ideas I have'nt thought of.
Sorry for the long post just frusterated.

 

Made the tester only hiss I could hear was`coming from a tiny pihole on the bottom of my forge mbc. Is that normal?

 

That's the bleed hole. IT lets out air when you reach the desired boost. Turn up the boost so that it makes no noise and keep testing up to 25psi. Just remember to turn it back to where you had it after you're done. If you have 0 leaks whatsoever up to this point, though, then it's unlikely to be a boost leak anyway. Are you sure it's 1.3 bar? I can understand it dropping to base wastegate pressure or something, but from 28psi to 19psi is weird.