boost gragh what do you think?

[Acezwild88]

ok the gragh below is from my profect it is graghing the boost. the boost is set to 15 psi. as you can see in the pic below is i only go to 14 and drops to 13 which is more visable in second gear i didnt take the car up to redline and i think in first i hit a fuel cut. i know the pic isent that great but in sec when it levels out it is rough looking like a mt. its not a great pic but i am trying to figure out what is going on with my boost i did a vacume leak test and i fixed the ones i found i need some more help thank you

 

[steve]

What are you running for a BOV? I don't see an aftermarket one in your profile.

Steve

 

[Acezwild88]

ive got the greddy type-s

 

[steve]

How high did you go to when pressure testing the intake?
Did it hold that pressure without additional air or was leaking?

Steve

 

[Acezwild88]

when i did the test the guage wasent staying up on the pressure i fiured it was just figured that the throttle body wasent trapping it in i didnt hear any other leaks though. so it didnt hold so do you think its still a leak so big that i just can't hear it? when it was pumping the pressure when up though and when i took it off there was some air that came out.

 

[steve]

If you can't hold pressure with a compressor how are you going to hold pressure with your turbo? You should be able to pressurize the intake to at least what your boost pressure is set to and hold it.

Steve

 

[Acezwild88]

what i dont understand is why if i set my boost to 12 psi it gose up to 11 and drops to 10 then if it can hold 13 when i set the boost higher why cant it hold 10?

 

[steve]

Honestly, I don't know.
But if you have a boost leak why try to figure out the strange behaviour when fixing it should help.

The throttle body isn't going to trap air in the intake during a pressure test. Air flows through the FIAV and BISS and around the slightly open butterfly just like it does when the car idles.
That's why it's important to make sure the engine isn't stopped at the small window of overlap when both the intake and exhaust valves are open in a cylinder. The pressure test checks the entire air path including any cylinders that might have their intake valves open.

Steve

 

[Acezwild88]

thanx alot steve ill try the test again and if i cant figure it out ill just blow it up
but it sounds like a vac leak to you?

 

[steve]

but it sounds like a vac leak to you?

We are talking about boost but from what you have described I'd bet you have some more intake leaks. I could be a bad vacuum line or just about anywhere else.

Good luck, it helps to have a friend help and use soapy water if you need to find the leaks.

Steve