Vacuum/boost Issue. Fuel cut off.

[Almit3yMush00m]

Alright so I've owned my MSP for a while now and I've slowly been trying to sort out issues with it. I just replaced all the vacuum lines with nice silicone lines andreplaced any of the factory plastic t's with larger brass t's. I have an hks bov and it just doesn't seem to open. The way I have the vacuum lines run is: Vacuum comming straight off the top of the intake manifold. down to one of the brass t's; from there it splits to the waste gate and to the bov. I have put a vacumm gauge on both the ends that are coming off the t and at idle I am getting 20 psi. When I boost the bov doesn't open and I get alot of turbo surge. I have run a vacuum line just straight from the manifold to the bov as well again getting about 20 psi when at idle and it will open the first stage but thats about it (I'm running at 8 psi boost). Hks is not a replica. The modifications I have are a corksport cai, corksport fmic, and a steedspeed exhaust manifold. How should I be running the vacuum lines for the wastegate and bov.

Also side note. When I run the car for a while there is a high pitch scream that comes from the engine bay. I'm pretty sure I've figured out that its coming from the waste gate because as soon as I take the vacumm line off the waste gate its stops immediately, put vacuum back on and it starts again. When im boosting my boost gauge shows it steadily keeping boost at 8 psi. Any thoughts on that one.

Lastly, when boosting I get fuel cut off. Its only when I'm at wot and really into the boost. It's slight but its annoying, Also seems to get worse when its colder out.

 

[hornsfan10609]

Is the wastegate diaphragm leaking? I think the 'fuel cut' you are experiencing is hesitation from the stock tune.

 

[Almit3yMush00m]

I think you might be right on the tune. As far as the wastegate diaphragm its the only thing I can think of that would be causing that noise since as soon as I take vacuum off it it stops. Just wanted to see if anyone had a different idea about it as well.

The main Question was about the vacuum lines and where to run them, as well as a possible reason why my bov isnt opening even though I have 20 psi of vaccum going to it. If the waste gate is leaking could that screw up the vacuum thats going to the bov since there are on the same vacuum line with a t?

 

[wmoesser]

I had a similar issue in my car and it turned out to be a rip in the bypass valves diaphragm. I'm using a forged bypass valve, after I got a new diaphragm my over boost fuel cut stopped.

 

[hornsfan10609]

Idle should be pulling 24-25 inHg

 

[Almit3yMush00m]

Ok with my vacuum gauge Its pulling 20 inHg at idle, im going to work on it some more today and see if i come up with any other issues. There are no leaks with the hks.

 

[Almit3yMush00m]

So I did some fiddling and who ever did my vacuum/boost gauge had it on its own designated vacuum port which is fine but it wasn't giving me a completely accurate reading. I put a dedicated vacuum to the hks and then put the vacuum/boost gauge on the same line as the waste gate. Well when I did that suprise! I was only getting about 3 inHG of vacuum so I'm pretty sure my waste gate is shot.

Does that sound about right or do you guys have a different opinion? I could be totally wrong this is my first turbo car so I'm still learning all the fun things that can go wrong.

 

[hornsfan10609]

Replace the WG already man, stop second guessing yourself you are making it so much more complicated than it is.