[Stu Hagen]

You already answered your own question. If you hear the Psssh when turning the eTTC switch, then the tank is good. I use my switch alot, because of road racing. I do notice my car acts up when I release the switch, basically what you say. After sn ECU reset and about 10 minutes, its back to normal. What happens is that there is still pressure on the actuators, and one of the 2 ones sticks open, hence what you have going on. If one or the other actuator is stuck a little, your boost will drop, BUT you will still have full boost after 4200 or so. If you have still little to know boost above this, you have a cracked hose, or something wrong with either the IACV or EGCV. If either one of those are closed, you will never get much higher that 11-12 psi

 

[Stu Hagen]

The seq. system is really a well orchestrated system. If any one item craps out if effects everything. It could be a faulty VSV, or a actuator that is going bad. The actuators are a diaphram/air based unit. If there are and pin holes in the they "leak" It is usually not that big of a deal, especially if you are in a constrant driving mode because there is constant pressure all the time. As I recommend to alot of people that are seq junkies, it is a good investment to get a hand pressure pump/gauge. You can test every actuator and the system with this and you can find bad components alot easier. They are under $50. You can pump up actuators and watch how slow they release, or hold. Also a good way to check pressure tanks too. If any of the 2 IACV or EGCV are not working, or opening properly, you will never get full boost. If they are still pressurized, then all you get is "lag" up to 4200 rpm. But still you should get full boost. Blow through both VSV's and make sure you can't blow through them without any power to them. I have a "test" VSV page on my webpage. LAstly, I would do this. Turn on your eTTC switch. Go out a do some 1 or 2 healthy pulls. Stop and pull over and pull the IACV hose going to the pressure tank. "AT THE SAME TIME", (better to have 2 people) have someone peek down at the EGCV actuator rod. When you release the pressure, the rod should close, or "return" Do the same thing for the IACV. This one you can see yourself because it is right there on top. It is possibe that you installed the eTTC wrong, and it is not shunting out the VSV properly. This would be your problem as well.

 

[Stu Hagen]

http://www.97supraturbo.com/Supra Scans/WastegateVSV.pdf

This is a generic test proceedure for all VSV's. It is pretty simple, except you need to remove them to do it. I suppose you can do it in the car, its that you need to apply 12V across the terminals. No 12V+, they are closed, can't blow thru. 12V+ applied, it opens and you can blow thru the 2 nipples. Sounds like your wastegate VSV has gone bad.