I'm in the process of switching back over to ECU controlled boost. I have the GM 3 port installed already, but have taken out the EBC I was using before. I'm waiting on my tuner to have to free time to get to tuning my car.

In the mean time, I ran a hose to from the compressor side to the wastegate so that I'll run wastegate pressure (12psi right?) and be able to drive the car until time to tune.

The problem I'm having is that my boost levels are way above normal. I hit 20psi if I step on it. In the past I had to run off just wastegate when my first EBC went out, and it would hold at 12psi no problem.

Since then I have changed out the O2 housing... I was thinking boost creep for a awhile, but it gets to 20psi and stops. Wont go higher. Maybe the wastegate actuator diaphragm is bad?

Any ideas?

 

Probably you should try lowering the waste gate spring pressure via the threaded actuator rod that connects the actuator canister to the pivot arm peg on the flapper valve. It sounds like spring pressure is too high. Shoot me a PM if it looks like too hairy a task to tackle on your own.

There is a how-to thread somewhere on the Forced Performance site. I have never seen it so I can't post up a link. But, you can search around on their site.

The installation of the aftermarket O2 housing may have contributed to the rise in boost pressure. At any rate when you adjust the waste gate spring pressure you should first adjust the actuator rod length to where the hole on the turnbuckle's flat mounted on the threaded end of the rod freely slides on and off of the peg on the pivot arm of the flapper valve. This setting should give you the 10-12 PSI that you mentioned.

 

yeah, I tested the diaphragm today and everything seems fine. I'll extend the arm when I put it back together and see what happens. I dont think the arm length was ever changed but I could be mistaken. I'll update tomorrow when I complete it. Thanks for the advice!

 

Did you remove the actuator from the car and test it on your workbench? Or did you test it while it was still bolted onto the turbo? How did you test it BTW?

 

From the factory the actuators usually come preloaded to about 14 PSI, I think. Which probably works out to the turnbuckle being turned in about two or maybe three full rotations. Although I may be wrong because it's been a few years since I have experimented with stock levels of spring pressure.

When you install it at the actuator rod's loosest possible setting, that's commonly referred to as base pressure( I think?). That is the point where it just slides on w/o having to pull on it at all....Then we are talking about somewhere around 11 PSI.

 

I just want to make sure that we are really starting out from square one. It worries me that in the first sentence above you say that the 3-port is "ALREADY INSTALLED."

So, I need you to clarify as to whether or not the 3-port is totally disconnected. Is the 3-port connected in any way via vacuum hoses to any of the nipples such as the one on the MAF hose? Obviously it is not connected to the nipple/port on the compressor discharge J pipe because the new hose that you are running from the WGA is connected there, right? And furthermore there is nothing connected to to any possible "T" in the DV/IM line, right?

I imagine that when you state that the solenoid is already connected you just mean that it is connected electrically to the wiring harness, right? This would be OK. It just can't have any of its three ports hooked up to the any other vacuum/boost ports in the engine bay.

So, with the 3-port totally disconnected and all other open ports/nipples and open hose ends pugged off with golf "T"'s etc. When and if then you were to run a hose directly from the J-Pipe nipple to the port on the actuator hat....and then you get a 2o PSI reading...then you first need to try readjusting the length of the threaded actuator rod to th epoint where it freely slides on and off of the peg of the flapper valves pivot arm.

With the hose connected in the above fashion and the actuator rod adjusted to the prescribed length....then you should be seeing base pressure(10-12 PSI). If not, and instead, you are still seeing a 20 PSI reading, then you need to start trouble shooting because something else is wrong.

 

I tested the diaphragm by removing it from the car completely. I put a new hose to the nipple on the actuator and hooked it up to my air compressor using blow gun with the pressure turned down. Gave it a little air until the arm moved. I did a second test buy submerging it in water and working out any bubbles. Then gave it air till the arm moved and held it to see if any air would escape. No bubbles came out.

As for the 3-Port. Yes. It is in the car, but completely disconnected. No hoses running to it, and the pig tail is not plugged in yet. I left the factory pig tail plugged into the factory boost sel.

Now when I removed the actuator from the turbo, there was no tension on it, but the turn buckle was threaded on about 50% down the threads on the arm. I'll loosen that up and try it all out again. I didnt get a chance to work on it today, but I will tomorrow evening, then I'll update.

Thanks for all the help.