Over Boosting issue

[kinz1987]

Ok, so I have an 05 GT. It’s got an aftermarket turbo, with an external waste gate, and a lot of supporting upgrades. Recently I noticed some of my monitoring items acting up and then Monday morning it started over boosting. I only apply about half throttle and my boost spikes to about 25 psi and then the computer cuts the power. I checked all of the vacuum lines (and replaced one) nothing looks out of place. Does anyone have any idea as to what I should check? All of my upgrades have only about 4k on them. And the engine only has about 6k. Edited May 20, 2021 by kinz1987
Update

[armypilot]

My overboost issue was caused by a slightly misaligned wastegate arm - wouldn't open. I have 104k on my car, so I just replaced the stock boost solenoid and cleaned out all of the plumbing.

 

I cut my WG arm, threaded it and connected with a coupling nut. Adjusted and no more overboost.

 

Here are the steps I used until I realized it was the WG arm (GoPros are the BEST!)

---taken from subaruidiots.com---

1.) Decat + High flow induction – Cure: Reduction of the solenoid duty cycle or alteration of restrictor size will help return boost output to its normal level.

 

2.) Split, poor fitting, or disconnected pipes – Cure: Replace or refit pipes, the pipes that will cause this issue are between the wastegate actuator, solenoid, and the turbo. Including up to the restrictor on the return pipe of the 3 port solenoid.

 

3.) Manual Boost Controller – Electronic Boost Controller set too high – Cure: Don’t be so greedy and back the boost duty/adjuster off to a safe level.

 

4.) Restrictor Pill not fitted / size incorrect – Cure: Ensure restrictor pill is fitted (3 port) if so on a 3 port reduce the restrictor size and on the 2 port increase the restrictor size to reduce the boost to a safe level.

 

5.) Clogged 3-port solenoid: It is possible that the flow of air through the 3-port solenoid could be restricted between the turbo outlet port and the wastegate actuator port if the solenoid is very dirty (usually oil vapor from the intake system), this allows the wastegate to remain clamped shut longer than it should be causing a potential overboost situation. Cure: Clean with carb or clutch/brake cleaner.

 

6.)Loss of solenoid funcation: Although this is not bverboost it shows itself with very simmilar symptoms, its an interesting scenario. It is possible for the solenoid to fail or even stick shut while under boost. This will result in a rapid reduction of boost pressure to wastegate pressure approx 0.5 BAR. So if you were running at full boost 1.0 BAR for example and the solenoid was to fail shut it would feel just like overboost as the wastegate rapidly opens due to the solenoid blocking off the spill from the wastegate. Cure: Either clean the solenoid with carb or clutch+brake cleaner or replace the solenoid.