I've always been fighting this never ending battle with compressor surge. I've used different BOV's, adjusted the springs, used different vacuum sources, different sized line vacuum lines but nothing ever works. I'll almost always get compressor surge right off the bat after letting off the throttle but a split second after that, the BOV would finally go off. Like it was delayed. Finally last night in my buddies talon, I noticed when he let off the throttle, 20in vacuum was created like instantly. Then when I drive my car. I can physically watch my needle go from say 10psi to 20in vacuum slowly. Like it doesn't pull vacuum very fast. So I'm guessing this is why I get a surge at first. there is not enough vacuum to open up the BOV yet until after the surge when the engines created more vacuum. The car runs fine. No vacuum leaks. between 20-22in vacuum at idle. Just is slow to create vacuum on throttle lift. Any ideas?

 

i think because of either cam overlap or intake cam size can cause you to not make vaccum quickly, i cant remember exactly what it was, but maybe this will point you into some general direction

 

Check to make sure the throttle plate isn't sticking inside the throttle body. THAT would be my first guess is that it got all gummed up and thus is causing a slow return of the plate... thus slow vac development.

 

I can snap the throttle plate open and and closes really fast. Like nothing gummnig it up. The cam voerlap could be an idea tho... I guess I can check my valve adjustment again.

 

TTT

 

have you tried running a single line from the intake mani to the BOV? Could be a leaky T, or some other connection.

 

yeah I've tried about 3-4 different locations. all the same... If this wasn't a expensive turbo I could careless.. but no. lol. I can't see the cam overlap time being that far off to create slow vacuum cause it runs like a champ. ran a 12.6@120. I can'ts ee me running taht fast of a time if the overlap was all messed and losing compression etc

 

pull your intake cam off and pressure test your manifold

 

I'm done a bosot leak test and filled everything with pressure. no leak.

 

where is your boost guage attached? is it after throttlebody?

 

yes it is after TB. it's on the vacuum manifold T'd off from my brake booster