So about a week ago I was trying to top out my car and once I hit 160mph it felt like I lost a lot of boost and it wouldnt go any faster! I also heard a weird sound. I then did a couple of 3rd gear pulls and where I'm usally set to 26psi I was only building 20psi and it wouldn't hold it either. It would hit 20psi then go down to 18 then back to 20. Also when under full throttle and I'm building 20psi there is a really loud fluttering sound(it sounds like if you put a piece of paper flat up to your mouth and blew on it). The only time the car makes the fluttering sound is under full throttle. So at first I'm thinking that I've got either a boost leak somewhere or maybe an exhaust leak. I checked all my IC piping and no boost leaks there. So then I started looking at my manifold and there was carbon all around the block where the manifold bolts up to. I then pulled the manifold off and changed the gasket and torqued everything down and did another 3rd gear pull and sure enough I'm still only building 20psi and the fluttering sound is still there! So now I'm thinking there might be something wrong with my interal wastegate or maybe my BOV. Maybe the springs are messed up in one of them or both, but I'm not sure. Does anyone have any idea what else it could be? Thanks!

I've also got a video of me doing a launch where you can hear the flutter sound if anyone wants to hear it just PM me with your email address and I'll send you the video.

 

this is a long shot but maybe pull the intake off and lower ic pipe and check to see if your leaking oil? maybe you have a partially blow seal? i guess you could tell if you blowin out blue smoke...

 

hmmm possible a wastegate, that would allow for the drop the rise in the boost

 

Is there anyway to check for a broken wastegate?

 

ummm i dont know that is a good question though

 

Well I know there is a spring in the actuator...it could maybe be broken but I dont know if you can open that up to look at it or not.

 

idk if the spring is so much as broken but just weak so it will open to easily

 

Yeah it might just be to weak to hold that much boost. Do you know how much boost the stock actuators can hold?

 

i think 11psi?? not positive though

 

Ok well I'm going to see if I can maybe take it off sometime this week and see if I can take it apart to see if there is anything wrong with it. I'm also going to get ahold of my tuner tomorrow and see what he thinks. I'll let you guys know what I find out.

 

The stock actuator cannister cannot be disassembled!

 

Did you get underneath your car and fully check the connection between the IC outlet and the UICP?

 

Yep! I checked all the IC piping and there are no leaks there.

 

So how are you controlling boost on your car(MBC, BCS, EBC, etc.)?

 

Apexi AVCR