Only OBDII codes in the car were cat thresholds, both sides (which is normal as I don't have cats on this exhaust at the moment).

No other codes.

 

MAF test ok. Taking the connector off the MAF elevates the rpm instantly then the engine idles a little randomly until I plug the MAF connector back on.

 

I would change oxygen sensors ... just give a try !

 

All 4 O2 sensors read perfect on OBDII scan.

Is there anyone who knows how to check WG actuators plus make boost leak check?

 

Will check actuators tmrw. If problems persist after that I organized to get the car datalogged next week.

 

Double checked the FPR vacuum line. It's on and tight.
It doesn't have a clip to hold it but it is for vacuum and in OEM condition this line is just plugged onto the FPR w/o clip.

 

Vacuum and boost!

 

I've used this method in the past... affordable DIY: http://forums.turbobricks.com/showthread.php?t=92396

 

Boost holds steady at 0.9bar in 4th gear.
0.9 - 1.0bar in 3rd gear.

In 2nd I see as much as 1.2, maybe I hit the 1.3 which sends the car into limiter?

Datalogging the car:
O2 lambda looks even and curves are smooth, appr 0.73-0.77 in the critical range.

Cam-shaft angle sensors look consistent (doesn't look like dips/glitches).
They are both at 30 +-1 from 2500 rpm and stays there till 6000 rpm (had to release throttle at that point).

Actual boost vs setpoint boost:
Big deviation - with setpoint 1800-ish hPA - actual boost shows as much as 2200 hPA.

 

this would defiently send the car into limp. get a hand pump and check when the wastegates on the turbos "crack". a lot of pwople modify or tighten k24 WGs to sustain boost better and spool quicker. your tune

can you post print screens of actual logs?

what rpm were u seeing a 1500hpa setpoint? Thats low...

 

One thing that looks wrong to me is actual throttle angle:

- I do a run with gaspedal at 100% from 2000 - 6200 rpm
- At 4500 rpm the throttle body closes to 32% then gradually opens back up to 44%.
- That is synchronized with the boost sensor value reaching 2100-2200hPA.

My guess would be "overboost" or knock detection, so the ECU forces the throttle body to close up.

On other softer test runs, when I boost 0.8 (dialing the throttle to not boost more), the car runs ultra smooth.

My next step will be to put my stock actuators on these K24 turbos and try it as given the logdata it seems the K24 actuators (they are custom) hold too hard.

Does this seem like the right thing to do?

 

very interesting thread, I have a very similar but more like a misfire only at 3000rpm on a easy accel, heavy through this range car runs fine? changed plugs and wires but no change? I feel your frustration Mr.White...
Sounds strange but have you checked the voltage output? A friend of mine had a similar on stock TT and found out the voltage output was way off causing it to feel blurping, on smooth accel it was fine? just a thought

 

Right now it's a stock X50 file. So it should be "low". But the 1500 was misleading it was an isolated point.

I would see setpoint 1800-1900 but actual boost would be up to 2200+.

 

throttle closing is car going in limp mode most likely. it would help if you psoted the actual logs. you need a tune if you are running after market WG actuators. having them is defiently a good thing and a worthwile upgrade, i wouldnt take them off. i just think your tuner needs to make "boost request" adjustments in your map that are in sync with your hardware.

 

Good suggestion will log that. How did he fix it?

Also a question, what does that voltage output value represent?