When I first got the car it had a boost gauge that reads up to 20psi and the boost would over shoot that even when hooked up to the boost stock control solenoid or if I just ran the vacuum line from the waste gate str8 to the pressure off the jpipe wich shud give waste gate spring pressure. decided to play it safe and get the car tuned and get a 30psi Bgauge since it was running such a high boost level, the previous owner said the stock wastegate he believes was upgraded to a 22psi spring although it appears stock. Turbo is stock td05-16g6-10.5t btw.standard evo5 gsr turbo.

Now the car wont pass 16psi , no matter what, if I use a mbc and turn the boost right up. connect jpipe to wastegate directly or even leave the vacuum line off the wastegate completely disconnected which in the past would make the boost shoot up to 30psi. I have done a boost leak test and it shows no leaks, checked bov.
What it cud be? Theres a upcoming race and cant go to the battle field on only 16psi although my car has a built 2.3L motor but 16psi on the stock turbo isn't enuf.

 

Are you bypassing the stock bcs completely??

 

yes. completely by passed.

 

So what is your set up then currently? Hose from the wga to the mbc and a hose from the turbo nipple to the other port on the mbc?

 

It sounds like a bad mbc or you have the hoses backwards. If it has an upgraded wga then that's why it is at 16 its running off the spring rate pressure in the wga. Try switching the hoses. It couldn't hurt you know.

 

boost pill in the line maybe?

 

right now I have the hose completely disconnected . so that will rule out something stuck in the vacuum lines. the turbo should overboost. but its hitting 18psi now but going back down to 16 by red line.

 

was the turbo rebuilt, or is original?

if the turbine housing is from ebay, then I would vote that the wastegate flapper no longer seals. they have a lower temp rating due to the metal used and dont last too long. Your symptoms sound like this issue.

 

Why do you think with the line disconnected that it would over boost? It would only run off the wastegate spring rate. What line did you disconnect? All of them?

 

ive tried them both disconnected . ive tried wastegate disconnected and jpipe pressure signal blocked off. ive tried them the opposite way. ive tried every trick I kno. And still nothing past 16. from my past experience with evos once a vacuum is popped off of the fuel pressure regulator it causes boost to not go past 8 psi or so but I checked all of that and everything is hooked up the way it should be.

my best guesses are the wastegate or the SAS(secondary air system aka antilag hardware valve leaking off boost or a bad wastegate spring that lost tention over time or flapper not closing fully. but just wish I can pin point before buying anything and wasting money.

thanks for the responses guys

 

Removed the wategate. Pulled on it to check the tension and realized that the wastegate pulls too freely and sounds like something is broken in there. So changed it swapped it out for a stock evo 8 wastegate now I am getting 19-20psi but cant achieve more boost than that . I desire 25PSI of boost. Last drag event 2 sundays ago was only able to do 12.8 1/4 mile on 19-20psi.

 

If you completely disconnect the wastegate actuator, it never gets any boost and thus never opens and can lead to a massive overboost. It has to be hooked up to a boost source to get the pressure to overcome the spring pressure.

 

Have you checked the turbo for shaft play?

 

But if the wastegate spring pressure is 12 psi stock, the wastegate should open at 12 psi I would assume but I see what you're saying if it has nothing to make it release at all it would just stay shut?

 

I had a similar issue tuned for 24PSI wouldnt get past 16 either. I ended up needing a new turbo..sucks but got me to go the FP red