use2windsurf

In an effort to increase the boost, I removed the CV and connected a manual boost controller between the banjo bolt and the wastegate. The boost controller seems to have no effect so I guess I am running on just spring resistance. I connected a hand brake line vacuum pump directly to the waste gate control line and tried to pull and hold a vacuum (with the car off). If I pump as hard as I can, I can pull about 10 inHg for a split second, but it bounces between 5-10. As soon as I stop pumping, it bleeds to zero in a second. Doesn't this confirm my waste gate spring is weak and maybe the diaphragm is damaged?

TurboTommy

Thoughts:
How much boost were you getting before and after the installation of the MBC?
What kind of controller is it? Bleed type or ball and spring?
Did you hook up the vacuum hand pump after the MBC for the test?
If it doesn't hold vacuum, I would think that, in fact, the diaphrgm is no good; but you'd think it would therefore be making more boost.

JacRyann

Sounds like you have at least two issues.

1. Wastegate diaphram appears to be toast. Have you tried testing to see if it holds pressure? Stock WG starts opening valve at 5psi and fully opened at 10psi. It should hold 5-10psi for over a minute.

2. Assuming that your wastegate diaphram is toast, you should be seeing +25-30 psi in the midrange!!! So most likely, you have a collapsed inner wall in your exhaust downpipe and mid-pipe sections. That restriction cannot be fixed by trying to turn up boost with wastegate controllers.

So, do the golf-ball test with your exhaust and fix it before trying to change the boost.

use2windsurf

It is a ball and spring type. For the test I disconnected the line from the output of the controller and connected that to the pump. I am getting 7-8 psi of boost. I have the LR chips and a 3 bar fuel regulator. It pulls, but not like it did.

use2windsurf

I have not tried the pressure test yet. With the wastegate line disconnected, I don't see any change in boost. I originally thought it was the CV which is one reason I put in the manual boost controller. Forgive my ignorance, what is the golf all test? Could this also be a vacuum leak causing this?

JacRyann

Golf ball test is where you take off the downpipe and midpipe and drop a golf ball in and see if it rolls out the other side. See photos here: https://rennlist.com/forums/944-turbo-and-turbo-s-forum/875553-installed-m-tune-running-pig-rich-2.html

User 52121

If you can't hold a vacuum then the diaphragm is toast.

Time to get a new WG.