Ultimatedsm
15+ Year Contributor
- 823
- 27
- Apr 20, 2005
-
Scarborough,
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Hey how are you guys doing? Alright my car has a stupid problem, it isn't a big drivability issue, but it is very annoying. Lets say, I am going a steady speed and punch it in any gear the car builds boost right away. However, when I am punching it in a gear(Boost hits instantly) than I upshift quicky and punch it, it takes forever to build boost.
So lets say I am rolling at 4000 rpm I punch it, it hits 15 psi in a few seconds. But than when I up shift revs drop around 4600-4800 than punch it right away, it takes a lot longer to hit 15 psi. I am guessing its my TURBOSMART MBC. I think when I had it hooked up backwards I could build unlimited boost but the boost was instant no matter if I was upshifting to another gear than punching it or on a roll on than punching it.
Any idea guys?
Hey how are you guys doing? Alright my car has a stupid problem, it isn't a big drivability issue, but it is very annoying. Lets say, I am going a steady speed and punch it in any gear the car builds boost right away. However, when I am punching it in a gear(Boost hits instantly) than I upshift quicky and punch it, it takes forever to build boost.
So lets say I am rolling at 4000 rpm I punch it, it hits 15 psi in a few seconds. But than when I up shift revs drop around 4600-4800 than punch it right away, it takes a lot longer to hit 15 psi. I am guessing its my TURBOSMART MBC. I think when I had it hooked up backwards I could build unlimited boost but the boost was instant no matter if I was upshifting to another gear than punching it or on a roll on than punching it.
Any idea guys?
Seriously, is the Turbosmart mbc ball/spring or bleeder? How is it routed? Have you pressure tested and make sure the mbc isn't leaking? It's possible that the wastegate pressure relief valve is not bleeding air off quickly enough either due to poor design or long hose route causing a delay in wastegate closing after you let off the throttle, just throwing some ideas out.
BOOST LEAK TEST!!! has been done my friend. One side of the MBC is hooked to the wastegate vacuum line, and the other side is T'd off to the BOV vacuum line. The boost has no problem hitting 14 psi. On a roll if I suddenly punch it, 14 psi hits in second, almost instant. But if I am punching it lets just say 2nd gear and hit full boost 14 psi than redline it then shift to the next gear quicky and punch it again, it takes a lot longer for some reason. BOV is recirculated for diagnose purposes. This problem goes away when I hook up the MBC backwards, but than I am just building unlimited boost 
