I have had the same issue on the same car two months ago.
I spoke about it in this thread : https://www.evolutionm.net/forums/sh...202&highlight=

The thread finish with "solved" exclamation,but it was only "temporary solved".I think that it was a coincidence.
After few days it returned.
Since then until today we have tried a lot of things.

1)EGR blocked (no effect).
2)ALL the vaccum and pressure piping checked,and ALL are fine.
3)Turbocharger entirely changed,because the dual flapper valve seems to be not perfect (and because a turbo upgrade was planned).The new turbo is a "titanium" 20G (EVO9 RS base).
4)BOV eliminated
With this last change the car go well for 1 week,but today we are at the start point.





Where 2b load increase and IPW drop the boost drop to 16psi,and I can hear a "psssssssssssssssssss" sound.
AFR remains stable,no pig rich or lean.
Boost limit is at 319 and boost cut delay timer at 1638375...

What is it?
A bad solenoid that opens at 5500-6000 rpm under WOT?
A MAF related issue??

 

What do you mean BOV eliminated? Did you just put a cap on the BOV spot?

Did you pressure check your piping instead of just looking at it?

 

I have no BOV now.Instead of BOV there are two caps.
The pipings were pressure checked
I forgot to write that we have also checked the boost control valve.

It is very strange that it isn't a pressure related issue,because I have 22psi from 3300rpm,but only at 5500-6000 rpm this thing happens.

 

You mean the wastegate or the secondary air system if equipped?

I guess it wouldn't hurt to find a MBC and try it see if your just having an issue with the solenoid. You don't have a boost plot so what happens at 5500-6000 rpms? Boost spike or drop?

 

Both tested,SAS and wastegate boost solenoid.

 

Ask a buddy to loan you out a MBC and see if it stops the problem basically just use deduction at this point and test out parts for faults.

 

It looks like the Wastegate duty cycle is getting pulled, but I don't know for certain since you didn't post your WGDC table and you aren't logging Load Error.

Other thing to check is that if you are still using the stock airbox and scoop, the scoop needs to have the little plastic rivets in it at the end, if it doesn't, it will get sucked up into the hood at speed and starve the car of air, and it will make that "pssssssh" sound.

 

I have tried to completely disconnect the line from wastegate actuator,in order to have the max actuator pressure possible.
So I'm sure that it isn't WGDC related issue.
I have also changed three pneumatic actuators.

I am not able to datalog Load error,but it is another story : https://www.evolutionm.net/forums/sh...d.php?t=386100


THE CAR HASN'T THE RIVETS.....I'll go to immediately to install them.

 

Have you tried running a length of hose directly from the turbocharger's compressor discharge nipple to the port on the WGA? Obviously you'd have to temporarily plug the two disconnected hose ends from the factory boost/vacuum hose harness, to prevent boost leaks while performing the test.

Then you set your maximum boost level by shortening the overall length of the actuator rod by rotating the turbuckle on the threaded end of the rod. This way you'll isolate whether the problem is a boost control circuit issue or not.

 

good advice was just about to tell him the same. i am currently having some boost controller issues and have done what is described above (running wastegate boost with some turns on the screw to raise boost).

 

I have already excluded the wastegate solenoid


This morning I have installed the rivets,and the issue disappear!
I have to test it more and more to be sure that all gone OK.
For now THANKS A LOT,I never thought to this

 

Glad that fixed it!