I recently had a good local shop replace my cooked VIII turbo with a near mint IX turbo, they also tuned it and installed a 3 port boost solenoid. Ever since they replaced it, i have experience a what i would call a stutter.

When i'm accelerating in boost (not WOT) and i start start to let off the gas, then the car start to stutter, like the BOV or waste gate were opening. I'm pretty sure i'm not hitting anywhere near peak boost. To avoid this stutter i've been just taking my foot completely off the gas when i am done accelerating instead of just letting up a bit.
Actually i'm pretty sure i am hearing the BOV or wastegate opening.

I'm going to ask the shop, what they think soon, just thought i'd get your thoughts too.

 

let me know what you did to fix this problem please

 

ive heard turbo stutter before and it was because a wastegate wasnt functioning so the air had nowhere to go

 

I have had that issue in lower gears, foot has to be off gas completely, 4-5th gear not so much. You just cant let up on a rev and them lay back on the gas without this issue. Rarey happens unless I am wearing thicker soled shoes etc

 

be careful
it may be compression surge

 

I have this same problem in 5th gear at about 7-10psi. If I am accelerating from below 4000rpm It will start stuttering.

 

oh this just dawned on me, if your getting more air than fuel, it also causes a compressor surge because the motor isnt putting out enough power to keep the turbo wheel spinning. in that case it might mean your car is running lean

 

I'm having the same problem ...
It only happen when i part throttle .. not full throttle ...
I even changed my BOV to HKS racing type ... but the problem still there ...
What the solution ?

 

same problem, im leaning toward a wastegate issue as well... any thoughts?

 

The stutter is the wastegate opening and closing at a high rate to try and keep a steady boost curve. There is a correction table in the ecu that determines how much percentage of wastegate duty cycle to add or remove depending on how far under/over the load/boost pressure shoots. What happens when the Wastegate Duty Cycle tables aren't tuned to minimize fluctuations is (A) boost overshoots (B) correction table tells the ecu to pull "X" percentage of duty cycle out depending on how far over it is (C) ecu pulls too much duty cycle out, now it's under the load% that it should be (D) correction tables tells ecu to add "X" percentage back to the duty cycle to bring it back up (E) which leads back to symptom A.

Once the wastegate duty cycle table is tuned, your boost will be smooth as glass all the way to the top of your rpm in any gear. I've gone through this before myself, so I speak fully from experience.

 

alright i understand that i can tune the wastegate tables, with that being said... how to i tune them? lol. What should i do if x is happening or if im getting the flutter at 2000 rpms what should i adjust?

 

The easiest way to find out is to look in the EcuFlash section of this forum under Important Links...there's a link there for how to tune stock ecu boost. Although the different pill sizes mentioned in the thread may not apply to you, the concepts are still the same regardless.

 

I'm having a shutter after letting off the gas that sounds like the BOV is opening and closing really fast giving it that flutter sound... any suggestions? It kinda feels/sounds like the BOV is opening late... I have a few minor upgrades nothing crazy. Do you think it's the same kind of issue or something different? I currently have the Greddy Type RS BOV in a recirculating configuration.

 

You're getting what's called compressor surge, and it's caused by the Greddy bov. You can do a single spring mod that will ease out the surge, but unfortunately then the spring is not stiff enough to keep the valve closed during idle and will cause the car to run poorly. I've tried most BOV's out there short of the Synchronic and can honestly tell you that absolutely none of them performed as well as the stock IX valve. Swap it back on and you'll see a world of difference.

 

Thanks for the advice, I'll definitely give a try and see how it does.