Boost issue

[Ja17Bmx]

I have no idea on this one, so I came to the experts for some help. The first time you boost the car, no matter what ( just started, been driving for awhile without wot) the car will build boost up the set 16 psi and then stop, studder and drop to 8-9 psi. Then after it does that, it will only build 8-9 pounds of boost in any gear until the car is shut off and drove again later. I have no idea whats going on? I did a thurough boost leak test, testing each part of the ic piping at a time and came up with no leaks.
The logger doesnt show anything abnormal, no execssive knock or anything. Im stumped on this one. When it goes up to 16 psi the one time it will, the car pulls excellent and the turbo doesnt make any weird noises. I checked the turbo for shaft play and it didnt have any. If i connect the line from the wastegate actuator to the nipple on the J pipe, no matter what the car will just build 8-9 psi and it holds it to redline without doing the said problem above. Its not until that my buschur boost controller is on the car that it acts up. Any insight to my problem will be greatly appreciated.

 

[pj91gsx]

maybe your wastegate is not working properly. Did you mess with the wastegate before? If you put seafoam in the motor it will help to spot exhaust leaks if you have an exhaust leak. It sounds like if you have a crack in the manifold, after you drive it for awhile a crack in the manifold could be expanding and letting lots of air out.

 

[Sam@RRE]

missing a bleeder valve between the MBC and Wastegate actuator?

 

[Ja17Bmx]

The manifold doesnt have any cracks at all. Ill check how tight the turbo and manifold bolts are in the morning. Yes, the boost controller has the bleeder between the pressure source and wastegate. Its a little hole in the brass nipple fitting. I cleaned it out already thinking it was full of crud but nada.

 

[talonalex92]

Sounds like a boost leak to me. Try un hooking your controller and running a straight line between the WGA and boost source. How long is the wait time? Long enough for the car to cool off? Does it only boost high when not fully warmed up?

 

[headsup7up]

i have a issue like this. only my car wont make more than 13lbs ever. theres no boost leaks, both wheels are good on the turbo, no cracks, bleeder valve is clear, when i disconect the WG it stays the same, no shaft play. im just as stumped.

 

[pj91gsx]

i have a issue like this. only my car wont make more than 13lbs ever. theres no boost leaks, both wheels are good on the turbo, no cracks, bleeder valve is clear, when i disconect the WG it stays the same, no shaft play. im just as stumped.

Describe how you did your boost leak test. Also put some sea foam in the combustion chamber so you can see exhaust leaks before the turbo. You could also have a big crack in the wastegate area that is letting air out when the wastgate is closed. If you can put 25lbs in the intercooler system and it holds boost for a good while then you don't have a boost leak. Also spray soapy water on the TB, intake manifold, intercooler, and piping. Just because you cant hear the leak doesnt mean its not there. I put my TB gasket on upside down and had a huge boost leak.