Hi,

My 10th AE has a knockoff HKS racing wastegate that I control with a Greddy Profec boost controller. I have made sure that the boost controller vacuum lines are ran properly according to the instructions.

My symptom is that I cannot get the turbo to pressurize above 8 psi. I have removed the wastegate for inspection and found one item that I would like to double check with you all:

The wastegate has two vacuum ports that I have the boost controller utilizing. On the very top of the wastegate (valve pointing down) there is an open threaded hole on my wastegate. In the picture I provided below, you can see a bolt in this hole.

Does this hole need to be plugged with a bolt? Is this a special bolt?





Thank you,

 

nothing special but yes the bolt should be in it debri (spelling) can get in there and ruin the diaphram

 

Would the missing bolt be the reason why I cannot raise boost above 8 psi though?

 

First of all, you are undoubtedly a gambling man to trust a knockoff wastegate. I have seen knockoffs fail right out of the box, literally. That was a Tial 38mm knockoff but I have heard of the HKS knockoff failing. I had an HKS knockoff and got rid of it because it just made me uneasy. On the other hand, many people report no problems with them.

You have your wastegate plumbing all wrong. You need to set it up like an external wastegate. You have to run your boost control solenoid to the top port and for the side port run pressure from the compressor outlet (or whatever source you choose, there are differing opinions). You need to configure your boost control solenoid for an external wastegate configuration. The pressure source for the solenoid needs to go to the "NC" port instead of the "NO" port, and then the air comes out of the "COM" port to the top of the wastegate.

Read the Profec B (or S or Spec II, whatever you've got) instructions available on the Greddy website. Do some searches in the single turbo forum, there is a lot of discussion there about this.

 

I have the vacuum lines setup just like the profec manual, and the selection in the back of the unit is set to the correct setting. I have double checked this.

I think you may have answered my question with this:

"The pressure source for the solenoid needs to go to the "NC" port instead of the "NO" port, and then the air comes out of the "COM" port to the top of the wastegate."

This leads me to believe that I do not need anything going to the very top center threaded bolt hole.

 

From this picture (just to explain how the vacuum lines are setup) I have the lower vacuum line going to the boost controller solenoid, and the upper line going to vacuum on the intake manifold. I am 98% positive this is correct

My real question is about the bolt hole circled below. Right now I have nothing there...no bolt, nothing. It is just open. What needs to go here?

 

Re-read what I wrote. You have them hooked up completely wrong. Hooking the top port to manifold pressure without the solenoid in-line can keep the wastegate completely closed and cause horrible overboost, depending on the specifics of how you have your boost controller hooked into the side port. The fact that it isn't overboosting may indicate that it is leaking. My HKS knockoff definitely did not have an 8psi spring (although yours might). I'd say there is a good chance you just have a POS knockoff that leaks.

Or your valve seat might be leaking or missing. There is a little seal thingie that goes between the wastegate and the flange on the manifold. It seals the ring around the poppet valve. That needs to be installed properly.

The top port uses pressure to close the wastegate (increasing boost), the bottom/side port uses pressure to open the wastegate and decrease boost (like an internal wastegate). The two chambers work against each other, and by regulating the amount of air supplied to the top chamber you can push the diaphragm closed during spool and then snap it open at your set crack pressure if it flows enough.

As far as that top bolt goes, I can't recall if I had anything in there or not. It may be needed to put tension on the spring, and that could explain why you aren't catastrophically overboosting right now.

 

^^^ you are correct it pre tensions the diaphram spring for the wastegate, as for the op you already told him how to fix it lol hes just to dense to relieze it

 

Very helpful. One more question: If the top port uses pressure to close the wastegate, would I not want the hole on the top center closed off?

Once again, thank you for the help.

 

usually its a hallow bolt with a jamb nut thats in the port

 

i cant believe no one helped this guy and also called him dense WTF is wrong with people on the forum I thought we where here to help people. What about hole that is circled?

 

i cant believe someone would bump a thread this old WTF is wrong with people


circled hole is to adjust preload.