I've had the same exact description with my turbo xs rfl valve when toying with springs. These matters are heavily subjective .. Can you massively increase your bov tension aswell? Are you venting partially to atmosphere aswell? That doesn't help a maf tune.

Wgdc remains 100 while boost surges the first time. The ripple probably skewed data in the following lines. Try not logging data to screen and drop back on those parameters you don't need in he future.

By chance what is your target boost or load?

 

Want to know how good things are drivability wise?

Creep slowly to high rpms and feather the throttle to e closed position. Play with that method in 1-2-3 and if you get bucking there ..

Part throttle is a delta p situation

 

Or perhaps he's hitting boost cut load?

 

Sounds exactly like the compressor surge I was getting with the stock turbo.
Set your 100% wgdc under this load- to 100. Also you can set your wgdc-tps table so that you only get 100% wgdc above a certain tps level. I had mine set so that I only got 50% wgdc until 70% TPS, and then ramp it up from there to 100% WGDC to 100% TPS.

 

Yeah, 23 psi at 3100 rpm sounds pretty close to the surgeline of the BBK. I had to limit boost to 28 psi before 3800 rpm with my BBK to prevent surge. Odd thing is that he said he didn't have the issue until recently. Maybe its cooler weather allowing high loads to be reached?

 

Yea maybe or he inadvertently fixed a boost leak that was causing him to not hit surge before.

 

Good points, I wish I had a surge issue that needed to be toned down. ???!???

In any case will the op be able to remedy this to gain the highest level of drivability , with ecu tuning?

 

I was able to completely eliminate it with the stock 9 turbo by doing what I said above.
I sure wish I had this problem still with my hta green lol

 

Well guys, hate to have to say this but I may never find out exactly what the cause was. Spun a bearing today I think. Or the motor failed in some other way. It's at the shop now.

Thanks for all the help anyway.

 

Bad bad month for the Evo.

 

That's a bummer.

 

Man that sucks sorry to hear it.

 

x2

Good luck on rebuild if you make the plunge.