Boost taper at high rpms

[Jesse36m3]

Is this normal to see running simply off of a wastegate spring? It happens no matter what spring I use. 6psi spring tapers to 3.5psi, 9psi spring tapers to 6. Not sure what the problem is. I just installed a delicious tuning EBC and fired off a log to my tuner in effort to remedy this because to be honest, my bone stock Focus ST feels faster.

Typically I'd point my finger at a boost leak, however, I ran a boost leak tester and my entire charge/intake side is 100% sealed. Exhaust too. Used all new gaskets literally everywhere, even under the intake manifold. Possibly a faulty wastegate?

Kit consists of:
JDL V2 "no-cut" routing
GTX2860R Gen II
UEL manifold
Recirculated Precision WG
Turbosmart BOV
3" downpipe to a JDL "ultra quiet" front pipe w/ cat & resonator. (maybe too restrictive??)

There is only one other thread on this entire forum with similar problems and his solution was to reference boost pressure on the coupler directly after the compressor housing, rather than using the pre-tapped fitting. I'm just wondering why this is a problem for us, but not the many other hundreds, if not thousands of people running this kit. Everything is 100% tight, has been quadruple checked, and even looked over by a good friend of mine who is a fantastic tech.

Essentially I just want to make sure I'm not covering up some underlying problem with the EBC in efforts to solve this mystery. Any other last things I should check / verify before I start messing with the EBC?

[mrloko]

bump for truth!

I'm looking to get this kit as well and wanna know if this is a common issue!

[8RZ]

Small turbo problems.

[pgranberg11]

that's a weird problem... i have the same kit, same setup, except i have a dual resonated over front pipe. so I don't have any cats... i wonder if your exhaust is too restrictive? purely guessing/speculating here... my boost doesn't taper with that turbo. I have an EBC too and it holds to it's target boost. the only thing i notice it does fluctuate from 10-11 sometimes when it's target is set at 10.. but i suppose 1 psi won't hurt..

but you have an interesting case.. i wish i had more info to share to help.. but unfortunately i dont.

[envyme]

Originally Posted by Jesse36m3

Is this normal to see running simply off of a wastegate spring? It happens no matter what spring I use. 6psi spring tapers to 3.5psi, 9psi spring tapers to 6. Not sure what the problem is. I just installed a delicious tuning EBC and fired off a log to my tuner in effort to remedy this because to be honest, my bone stock Focus ST feels faster.

Typically I'd point my finger at a boost leak, however, I ran a boost leak tester and my entire charge/intake side is 100% sealed. Exhaust too. Used all new gaskets literally everywhere, even under the intake manifold. Possibly a faulty wastegate?

Kit consists of:
JDL V2 "no-cut" routing
GTX2860R Gen II
UEL manifold
Recirculated Precision WG
Turbosmart BOV
3" downpipe to a JDL "ultra quiet" front pipe w/ cat & resonator. (maybe too restrictive??)

There is only one other thread on this entire forum with similar problems and his solution was to reference boost pressure on the coupler directly after the compressor housing, rather than using the pre-tapped fitting. I'm just wondering why this is a problem for us, but not the many other hundreds, if not thousands of people running this kit. Everything is 100% tight, has been quadruple checked, and even looked over by a good friend of mine who is a fantastic tech.

Essentially I just want to make sure I'm not covering up some underlying problem with the EBC in efforts to solve this mystery. Any other last things I should check / verify before I start messing with the EBC?

I have the same kit as yours and I experienced this as well. Have you found the solution? Do you have ig or fb so we can talk about it?