Over boost then returning to normal

[RaKid]

Hi Team, 

 

Boost gauge has recently started reflecting 19-20psi boost spike on initial wide open throttle (WOT) then returns to 15.9psi (1.1bar) after a few seconds. My understand is that 1.1bar is stock internal wastegate (IWG) pressure - could someone please confirm this? 

 

Turbo is VF28 and vehicle is V5 STI.

 

From the symptoms I believe that my IWG diaphragm has a hole and is leaking boost which is why it's taking 19-20psi to open it - could someone please confirm or deny this? Please provide a fact based response if you choose to do so. 

 

Secondly, for the duration that my wastegate is not efficiently releasing waste, 2-3 seconds, are my injectors pushing the required fuel into the cylinders?

 

TIA. Brett 

 

 

[Marky]

Which car? The v6? 

 

Your diagnosis is probably correct assuming nothing on the car has changed. To verify it's not simply the ecu doing something weird do a reset and see how it behaves

 

as for the fuelling - "probably" - can't be 110% sure. They generally are fine at the 18psi range but depending on modifications it could be pinging for that brief period

 

to answer if you think it's the gate itself - get a bike pump feeding into it with your boost gauge teed off  

[Guest]

Or run a line straight from compressor cover to internal actuator and see if it holds 7psi across the rev range.