T78 compressor surge

[Dragun]

Just a quick one guys,

Had my t78 rebuilt recently and reinstalled it. But now on boost it\'s not venting through the blow off valve, but I\'m getting compressor surge. Tried to loosen the spring in the bov as far as it goes but same thing. It never used to do this before the rebuild, what can cause this issue? I\'ve checked for vaccume leaks, also tried the other nipple on the uim for the bov connection. Can an exhaust leak cause this? Or do I just need a remap?

Troubleshooting guide would help lots. Thanks

[BlitzBoy]

BOV only vents when you step off the throttle.
Describe what you think is Compressor surge? does it happen on or off the throttle?

[Dragun]

Nah only off throttle when the throttle body closes. Before when releasing the gas it\'ll always vent through the bov. Now when releasing throttle on any amount of boost/rev range, the car stumbles and and a fluttering from the turbo.....kinda like the sound the transformers make in the movie xD haha only comparison I can think of.

I have a blitz bov, and the noise this makes is unmistakable, a big ptcshhhhhh! It now never vents through the bov and the fact the car stumbles on gear change on boost/releasing throttle it\'s def compressor surge. I\'ve got vaccume going to the bov, I\'ve pulled the line from the uim and def air coming out of the nipple. Could it be the bov is seized as the car has been sitting for a while. Only thing is it\'s welded on the pipe so can\'t even take it apart to have a look :/

[BlitzBoy]

sounds like the BOV is faulty , put a Mityvac on it and create pressure and vacuum see if it moves

[Dragun]

Will try that, thanks blitz