One of our scoobys is playing up, only pulling 5psi all of a sudden (the misses broke it) I have removed intercooler and checked y pipe and checked as best as poss for any boost leaks, brand new dump valve , to just to eliminate the boost solanoid I un plumbed the line off the T piece in the actuator pipe and to my knowledge it should of over boosted like crazy with the solanoid disconnected with open T piece , but still only 5 psi . Checked the turbo and there's no play in the compressor wheel and free spinning.new maff sensor. Checked Ecu no codes logged but reset anyway. It's driving me crazy I just don't no where to look now any ideas would be greatly appreciated HELP !!!

 

What are you using to measure the boost? Does it feel slow?

Try putting a boost leak tester on it and see if there any leaks you've not spotted and check that the actuator/wastegate is working properly.

 

Have a boost gauge in the car , just feels lack of boost otherwise drives fine , it's like someone switched off the turbo . Gonna swing by breakers today n pick up an actuator , I can't hear any boost leaks under load either

 

What year and model car?.

 

What intake pipe? Silicone? Possibly sucking shut.

 

It's a my99 uk turbo , changed the actuator no change

 

If you bypass the boost control solenoid it will only boost to actuator pressure which is circa 0.5

 

What's really bugging me is that when I removed the boost solanoid hose that's T'd into the actuator , it should of boosted stupidly even if it had a slight boost leak somewhere because in theory that T is a wide open mbc , but still only actuator pressure 5psi. So very confused lol

 

I'm sure that's incorrect because I have a mbc on my bug eye spliced into the actuator pipe, and by leaving the T piece in its bleeding the line so should boost stupidly

 

with a t piece it will bleed certainly. I wasnt allowing that you had the t piece open and thought you had plunbed directly to the actuator

 

Yes sorry I didn't make myself totally clear. So basicly I can't even wind the boost up even if I wanted to

 

Put back to standard.

 

It will over boost if you leave all the boost control pipework off, connecting the actuator to the compressor housing will mean that it run at actuator spring pressure....

As said, put all the pipework back to standard and check that the restrictor pill is still fitted.