Posted this on EvoX Forums, but figured I would ask here too.

Background 80k miles, 2010 Evo X GSR.

• Cobb Stage 1 AP
• ETS Upper intercooler pipe

Previously, car had catback, Cobb SF intake. Car was hitting target boost of 24-25 psi initially, slowly started seeing it decrease over time. Car fails to barely hit 20 psi anymore, but is consistently hitting 17-19 psi. Seen it spike to 21 on a good day.

Initially thought it might be leaking from the UICP, tightened everything down. Car seemed to be hitting 23 psi again, but after driving for 30 minutes or so, it went back to 18 psi or less. Hasn't improved since. Maybe heat soak? But I did replace the intercool with an ETS 3.5 and did not notice any improvement. Not really sure what I should try next. My mechanic believes it's not leaking as the boost is holding, but it just can't get past 20 psi. Spool seems pretty slow from what I remember too. Was thinking about replacing the wastegate and BPV and possibly rebuild the turbo. I read about Exhaust manifold cracks, but on the surface it seems ok.

Any other suggestions or things I should look into? Thanks!

 

You need to do a boost leak test up to your target level. Sounds like you fixed one leak, and then it started leaking in another location.

 

There is trove of information on this forum for issues like this. You need first to check what the ECU is doing. If it is truly aiming high and not getting there you will see the WGDC go up and up but not reach target. That brings you to number 2 - verify your wastegate actuator and door are operating (it won't hold boost if it is leaking past the turbine). After 1-ecu and 2-wastegate then check your boost controller itself and of course the boost leak which you already did. The list goes on and on as to what the problem may be, but that is where I would start.

 

Due to his wording, it doesn’t sound like a proper boost leak test was performed:
” My mechanic believes it's not leaking as the boost is holding, but it just can't get past 20 psi.”

The mechanic wouldn’t believe it isn’t leaking, he would know. It sounds like, while you are driving it holds at ~20psi so there isn’t a leak, which isn’t true. Also, if target boost is 23 psi and the system was only tested to 20 perhaps? I personally would test the simple stuff before involving a tuner.

 

Sorry, yeah, can confirm boost leak test not done, yet. Looking at just getting a compressor myself and doing it. Not sure where common leaks stem from, besides the intercooler piping.

But yeah, boost isn't fluctuating. It holds, but just isn't moving past the 18-19 PSI

 

I had a similar issue on my X and found a big leak on the lower factory ic pipe. I had to take the front bumper off to get access, but you might get lucky with how the clamps are oriented.

 

May have actually determined the problem. Turbo seems to be on its way out. Today it started making a propeller shut down noise on turn off. Can hear the metal clanking too.

 

Sorry to hear that, your boost leak probably contributed to the turbo failure. I am pretty sure that is how I lost my gtx 3071.