I've had my car running boost (0.6 bar) for a while now after its rebuild with forged pistons, rods etc and all has well so decided to turn the boost up to around 0.8-0.9 but it wont change.
I can turn my MBC in all the way so the ball is locked in its seat and it still only boosts to 0.6, I also undid it all the way and it still boosts to 0.6.
I had the MBC off and it seems to be working fine so im looking at the actuator but can anyone else suggest anything else to look into?

 

I knew you were from the UK cause of the "carn't".

But are you sure you have the MBC hooked up correctly

 

LOL

Yeah its right and it works ok if you try putting pressure to it off the car. Its almost as if the exhaust gas is pushing the waste gate open but thats just silly. I thought about taking the waste gate pipe off all together an slowly bringing it on boost to see if it will go over 0.6 but i dont want it to spike and blow the the baby.

 

i'm assuming this is in internal gate?

They're pretty cheap, I'd say get a new/used one before fiddling with it.. Worst comes to worst you'll need to resell it.

 

yeah it is internal.
I have spare one i can modify to fit if i need to, but hopey fully this one is ok.
Any othe ideas?

 

Is "carnt" proper english over there?

 

I would look into your Blowoff valve. I beleieve I am having the same problem as you right now. It turned up fine from 7psi to 9psi to 10 psi then to 12psi now, when I turn it up it will go a hair over 12 psi and then leak off back down to 12psi. I am positive the BOV is the culprit.

Phil

 

make a boost leak tester. pressurize it and find leaks.


And yes, "carnt" is proper english.. I knew a Family from England and they used it like it was normal..Funny thing is I lived in Costa Rica at the time. I actually also went to the European and American Academys when I was in Costa Rica.

 

I have a dump valve plug so will try that out later. I dont think its a leak tho because it flys up to 0.6 then just no more