To high of boost with MBC...screw is almost all the way out!!

[tom04841]

I bought a mbc for my 91 tsi. i have the adjustment screw into the body of the mbc about one turn, just enough to keep it in there, and the lowest boost i get is 17 psi.

Can i shorten the spring a little so i can make more of an ajustment to lower the boost?

 

[tom04841]

Well i decided to cut a couple coils off the spring. Put the screw in till it hit the spring then turned 1/2 turn.....13 psi. Turned another half turn.....14 psi. Thats all i am gonna do for now till i get a SAFC and rewire the pump. Still need to log a third gear pull to see if i am knocking. I'll post it in the tuning section once its done.

 

[bkruahnndon]

take the ball out and make sure its not gummed up with anything. i had the same problem with mine and when i removed the ball it had gunk all over it. cleaned it off and it worked just great.

 

[tom04841]

Its brand new....no chance to get messed up. It was just the spring was too long

 

[szewczyd]

Maybe I am an idiot but I swore that the more you turn the set screw in the less boost? I had a turbo xs back in the day and they said to bottom it out and turn it out I believe one full turn and then turn it out more as needed for higher boost.

 

[szewczyd]

Your post contradicts itself! First you have it all the way out then u cut the spring and its near all the way in? Why didn't you just turn it all the way in and back it out a little before cutting the spring.

 

[tom04841]

Your XS is diferent from any MBC i have seen. As you turn the screw into the MBC, it puts mor pressure on the ball, therefore taking more pressure to push past the ball, which in turn opens the wastegate.

Since my screw was all the way out, and i was still hitting 17 psi, i have to shorten the spring to give more room for adjustment.

I hope that was clear enough.

 

[bkruahnndon]

sounds to me like this spring just has too much tension. try a lighter spring. what brand/model is this???

 

[tom04841]

It was an ebay one. It works fine now that i shortened the spring a little. Holds steady at 14 psi. I posted the log in the tuning section. Heres the link. 14 psi log