86 951 Driver

Pics of pressure applied. It was 20 PSI applied to the line.







How far should it be able to open?

86 951 Driver

Does this need to be rebuilt?

86 951 Driver

It appears the thing will open all the way when it hits 20 PSI. Is that correct or should it go wide open once the PSI is at 7 or 8 PSI? Any help is greatly appreciated. I don't see how anything else could cause boost spikes or high boost.

Here is a small video.

User 52121

It should really only need to crack to start venting boost pressure. It looks to me like it's working fine. I'd back it up and look for something behind it. Like a pressure signal not getting to the diaphragm.

86 951 Driver

Well I put it all together and made sure there weren't any exhaust leaks.

I re ran the boost line from the intercooler pipe to the T connector. After everything was hooked up I tested. I made sure pressure was being sent to both sides of the T. I had air movement at the MBC inside the car, and at the wastegate. I hooked the MBC up and made sure the MBC when turned down all the way didn't let any air out. It passed. I then turned then **** up and air was coming out the other end of the MBC.

I went for a test drive unfortunately nothing really changed. Boost in 4th gear goes up to 15 psi up until about 4,000 rpm when it will continue to go up to 17,18,19 psi. Thats when I let off. I tried setting the MBC and the result is about the same. Turned all the way down or turned up a little bit same result.

Cliffs:
Same results. 4th gear up til about 4000 rpm I get 15 psi but after that it starts to build boost again. Yikes.

I'm stumped and out of ideas. The wastegate seems to work fine, the MBC will allow air to pass through it.

homerj

i didnt notice if u tried a new mbc? i had checked everything and bought a new fancy controller and still didnt work. bought a simple lindsey racing and it worked. i wonder if u could rig up an air compressor valve just to see if works.

refresh951

What spring is in this WG?

86 951 Driver

It is a Lindsey Racing Dualport Wastegate as far as I know there is only 1 spring that they put in their wastegate.

My MBC was brand new not used. Granted it has been sitting on the shelf for a few years, but it was brand new when I got it.

86 951 Driver

I have not tried a brand new MBC, but mine was bought new a few years ago.

User 52121

Take the MBC out of the loop completely. Run the WG in "single port" mode, with a single fresh vac line going from the banjo all the way to the WG and the other port on the WG empty. No T's, no nothing else, just a straight single FRESH line.