Boost issue....Help
 

I 'm using a T78 with a greddy Type R wastegate, when I run off of the spring alone it hits 1.25 bar and I instantly let off. Now thats at 1/4 to 1/2 throttle. I tried adjusting the spring with the adjustable screw all the way out and no change. Then I hooked up my mbc with a line from near the throttle, mbc line to top of the wastegate and the bottom part of the wastegate to a spare vacuum barb on the uim. Connected as said, I only get .58 bar with full or 1/2 throttle. I've already replaced the diaphragm and spring, so am I overseeing something?... Hopefully this isn't too confusing.

Thanks..

when you are running the spring alone are you sure you have the gate hooked up correctly?

Alex, give me a call and I'll get you straightened out.

B

Ok Brain...Thanks

Fixed?

Ok I still have the boost problem, update is new diaphragm and spring. I tapped into my compressor elbow and went directly to the side port of the wastegate with the top port vented. I replaced old some old coulplers and secured them with t bolt clamps. I have no boost leaks and I cannot boost past .50 with a .80 spring in it.

Bet you're blowing air out of the intake system somewhere and/or out of the exhaust either before the exh manifold or just before the turbo. If it ain't those two, then the BOV is venting. Nothing else explains it.

B

Alex! I just got your voicemail now. I'll be giving you a call tomorrow... Anyway, I agree with Brian, but you really really should have the compressor outlet tapped for the vaccume reference to the side of the wastegate. Having a tapped source downstream (closer to the engine) makes for a delayed reference. Take off that MBC before something bad happens!

Lance, I did tap into the compressor outlet and connect a line straight to the wastegate, the mbc isn't connected.