My boost gauge isn't going past 0 in 1st or 2nd gear then increases very quickly in 3rd and 4th. I also notice that once the gauge starts reading boost in third I can then go back into second and it reads it when I'm driving more aggresively. It seems like I'm making boost in those lower gears because my bov is hissing at me Any thoughts? I currently have the gauge hooked up to the vac line that goes to my bov. I tried moving it to the line that is suggested in the 3sgte maintance sticky but it doesn't seem to be reading correctly either. When it is hooked into this line it only goes -7 and still doesn't push past 0 in 1st and 2nd. Any help would be greatly appreciated. Thanks!

Ok the first thing you need to do is check for any vacuum leaks, did you do this, and does the car seem to be with no power?if it is normal it might be just a torn pipe to the boost gauge.

I haven't noticed any leaks. The gauge seems to work fine after 2nd gear. Could it be that the nylon tubing is too long? I have the excess kind of curled up in my dash. I thought that maybe because the boost pressure is lower in 1st and 2nd that it wasn't enough to get to the gauge and read the pressure. Just a thought I had. Any thoughts? I'll check the tubing. Thanks for your help.

How much boost does the car make in 4th gear?

Its normall not to make a lot of boost in 1st and 2nd gear, because there is not as much load on the motor as there is in 3rd or 4tth. So if your boost is set low in 4th gear, then you wouldnt see a lot in the lower gears.

Another part of it depends on your exhaust, and what kind of boost controller you are using.

In 3rd and 4th it shoots up to around 18psi when I'm driving hard...seems like it cuts off there. It seems like after 2nd gear everything works ok. The gauge just isn't reading past 0 in 1st and 2nd. Right now my exhaust is straight 3in pipe with no cat and a 3in dp. I'm working on getting a muffler and resonator on there As far as running a boost controller...I don't have one yet. I'm thinking about getting the greddy profec B.

And it is boosting 18 psi? you have to be careful man either that or there is something wrong with the boost gauge, have you tried an new one just temporary , just to see if it is th gauge on a standard st205 (the ones i work on) the boost is 13 psi and may spike to 15, is you turbo stock? and is the engine sounding normal? could you take a vid of you driving it?

It cutts off on 18PSI because the Fuel Cut Defencer comes in. Really dont drive it hard untill you find your problem otherwise it could get worse.

I'll see about taking a video once the weather gets a little nicer. Everything is stock except the turbo is clocked, 3in dp, and straight 3in exhaust. I'll take it easy until I figure out the problem. Hopefully it's not the gauge because I have it glued into one of those custom single gauge pods that were sold on here awhile back Thanks for your help.

its better the gauge than a bigger problem hear from you soon then...

the standard turbo will crap its self at 18 psi after a few boost spikes to that... atleast my stock turbo died after 3 or 4 times of hitting fuel cut.

so you have a full exhaust system 3" from the turbo all the way back... turbos clocked downwards i assume... your running a front mount air to air intercooler?

how is the boost being regulated? by the stock turbo wastegate or have you just got the vacum line disconnected from the turbo? take a picture of your turbo? there should be 2 tubes ontop of the factory wastegate... where do those go.

Yeah it's clocked downward and I am running a front mount intercooler. Right now I don't have a boost controller so it must be regulated from the wastegate. I'll look to see if the vac lines are hooked up to it. I bought this car not too long ago, so I'm still trying to figure out what the previous owner had done to it and what I need to fix / improve. Thanks for all your help.

I think you have a problem with your wastegate then. You should inspect it to see if its not stuck. Who clocked the turbo? That clocking bracket could have not been made right, or your wg flap could be getting stuck on the edge of the downpipe. It kind of sounds like its stuck open half way. This would cause you not to be able to build boost in lower gears, but over boost in higher ones, like whats happening right now. Inspect the wastegate.

Thanks for the input lagos. I'm not exactly sure who clocked the turbo. I'll take a look at the wastegate and see if everything looks alright. I appreciate all the help

ok something is realy wierd here the stock boost for a st205 is only 8psi.. i have everything hook up on my swap and the only boost i get without the boost controller is 8psi i am currently doing 18psi with the boost controller hooked up. it seems when i dont have the boost controller on my turbo. it shows on my boost gauge that im running 8 psi in all gears.. hopfully your turbo isnt spiking on u with tht stock wastegate.. yeah i give it a couple more spikes up to 18 psi and that turbo is gone. check the wastegate out and see who clocked your turbo. a ct20b turbo is worth alot and man u dont want to lose one of those to turbo spike.

stock boost for an st205 is about 13-14psi.

you wouldnt damage the turbo from a boost spike, but you could damage the motor. 18psi is really pushing things a bit far. i would keep the boost at 15-17 psi on an st205.

Is safe mode around 8psi? This isn't my everyday driver so I have some time to figure this out Hopefully it's soon though. If I drive it a definitely wont be pushing it hard....don't want to mess up this engine. I'm going to look at the wastegate tomorrow and see if everything is alright. Thanks again for all the input. I'll let you know what I find out.

Minimum (ie wastegate) boost is 8-10psi on the ST205. Stock when the TVSV is active is 13-14psi. I run wastegate boost for daily driving, 14psi for fun and 17psi on the track with my boost controller.

If your turbo was clocked for a front mount intercooler or something, the wastegate probably was relocated incorrectly. You also probably have your electronic boost controller hooked up backwards or something to cause it to overboost when you have it on...

-Charlie

Here's some pics...not sure if these help.





Until I get this taken care of I'm going to be taking it easy. Thanks for all your help and advice.

Based on the pictures, I'm forming a little theory here:

It looks like the wastegase actuator has something welded directly on it. This could have seriously damaged the internal diaphram. In lower gears, the wastegate is open enough to keep the turbo from spooling. In higher gears, the wastegate doesn't open far enough because it may be hitting the downpipe flange.

Anybody else have any theories?

-Charlie

The Diaphragm is surly damaged !!! It should be replaced immediately

Thanks guys. So I can just get a new diaphram? I'll look around on the net. Hopefully this fixes the problem/.

Youll have to try find one and you need to buy the whole actuator the diaphragm is not sold on its on

Nope. You have to get a whole new actuator and make a new bracket for it. I believe Dr. Tweak (a memeber on here) has brackets he can sell you to mount it.

You will also want to make sure the wastegate itself opens up freely. When the actuator is disconnected, make sure it doesn't hit the inner part of the downpipe flange when it opens (many cheap downpipes have been known to interfere with the wastegate).

-Charlie

Sorry if this is a stupid question, but how do you get the wastegate actuator arm off the lever that opens the flapper door? I don't have a good view and I'm trying to get this thing off without removing the entire turbo.

It should just be a c-clip. Don't loose it!

-Charlie

So I know my wastegate actuator is F'ed, but I disconnected the vac lines going to it to see if I would build any boost in 1st and 2nd, but still nothing. It goes to 0 but nothing past that. The flapper door is shut, so shouldn't I be making boost in these gears. Hopefully my turbo isn't messed up. I checked the IC piping for leaks and I can't seem to find any, but I noticed that while driving it seems like there is a definite leak somewhere. My boost gauge will go to 0, but then I hear this hissing sound and it slowly drops back into vacume. Thoughts? Is it time for a new turbo to go along with the new actuator? Is the car still safe to drive as long as I"m not driving it hard? I definitely don't want to mess this engine up

1. your turbo is not messed up.
2. stop checking your boost in 1st and 2nd gear. boost should always be checked in 4th gear. if you can build boost in 4th, your turbo is fine.
3. yes, the car is safe to drive the way it is, as long as you dont over boost it by running with those hoses disconnected.