boost blowing off under load?

[l3lue]

What would cause an 87GN Stock to lose boost under load? Launch the car get up to about 50MPH under boost then it blows out the wastegate without letting off of throttle? Looking at buying car but it's doing this?

 

[BMR]

Mine was losing boost on the shift. Actuator was not tight enough.

 

[l3lue]

I wasn't near the car so I had my friend drive it he said it would come up to a shift point then blow off , loose actuator most likely?

 

[l3lue]

Did it both times he stabbed the throttle, it would shift normal through gears otherwise though

 

[l3lue]

here is a video

 

[Chuck Leeper]

Sounds like boost backing up thru the intake. Does it have a BOV on it?

 

[l3lue]

I dont believe it does

 

[l3lue]

Confirmed it does not have BOV

 

[l3lue]

Here the code sticker- looks like a non posi car? Anything else you guys notice good or bad?