Ok so this is for my friend with a 93 civic hatch. it has an obd-2 b18LS, T-3 turbo, HKS SSQ BOV, 9lbwastegate spring, tuned on AEM EMS and e-85.(put down 256 whp)

well anyways the problem, he had a ---- *** ebay manifold which as we all know crack, so it went to ---- and we just got the new cast style manifold all hooked up earlier today.....but under full throttle and full boost it will out of nowhere slowly let out the BOV and stops building any boost at all even whille giving it full throttle....were alll just sorta lost on y this would happen, because if there was a boost leak y would the BOV go off?....any help is much appreciated.....

 

did it happen just once or more than once cause if it blew off and then doesnt build boost any more maby a charge pipe blew off melted a coupler.

 

no it would blow off and stop building boost....so we let off, he down shifted to 4th and it built boost again till just a few seconds at 9psi then it did it again

 

Did he increase the boost when he put on the new manifold? Sounds to me like air is leaking out of the blow off valve. See if you can adjust it to hold in the boost. Might want to see if all vacuum lines are installed correctly also.

 

no we did not adjust the wastegate it has the 9lb spring in it.....and all the vacume lines are hooked up correctly....and i dont think u can adjust his bov....its the brand new HKS super sequential one

 

if ther is a small leak in the hose going to the bov then the boost in the charge pipe could push the bov open

 

do u mean the vacume line connected tpo the Bov?

 

did you undo any vacume lines ? if so and you didnt connect them right it may be turbo surge

 

they way bovs work is pressure from boost holds them closed (pushes against itself with the help of the spring) and when you close the throttle, the strong vacuum on applied then pulls (against the spring) while also being pushed by the pressure hehind it and opens.

as they've said, if the line to the bov is not right, the boost could just push it open without the appropriate boost pushing it closed from the diaphragm. if this is the case, you might expect that it doesnt open decisively at throttle closed.

the bov should be open sitting idling with a strong vacuum. check this. if its not, then you probably dont have a vac signal going to it.

a leak in the vac line like phil mentioned because of the size of the tube will negate most of the pressure applied to it.