Boost Problem I need help!!!!
 

I have a 86 944 turbo. I have a manual MBC that i can turn al the up or down and will not change the boost level. I have a duel port wastegate, Lindsey chips, and the MBC. I cannot figure this out or havent looked in the right area. Please give me an idea where to look and what for. All parts are less then a year old. Thank you!!!

Well. Step 1. Check all boost related lines.

Have you changed anything recently? Did you just install the MBC and problem started or is this a new issue on a car previously running fine. It is more than likely vacuum related. check all lines and report back.

All new lines and hoes. I have it hooked up all year just never got around to figuring it out. All lines check out fine. No leaks.

Well then either your vacuum wiring is incorrect, your waste gate diaphragm bit the dust, or maybe your MBC died?

Have you looked at Lindsey Racing's site for advice? I assume that they diagrams on how to hook things up.

Good luck, Keith

Looked over it. All vacuums are correct. I have no idea how any of the two would be bad. How do i tell if they are bad. My car does boost to 10 but when i turn the MBC all the way down it goes to about 7, all the way up is 10 no higher then that.

Gordon15734;

Lower port on wastegate goes to manifold vaccum. Upper Port on wastegate goes to MBC out. and inlet pipe vaccume goes to feed MBC as your reference signal.

Use a mightyvac hand pump to check your wastegate operation.

MBC they go bad after a while (don't trust none of them...) Use a Greddy Profec B or Type s electronic BC for best control. Had mine for over 10 Yrs...You can tune in the boost response.
Later...