03 allroad boost issues

[kaclaytor]

OK so I've been fighting limp mode for months now. When it first started I thought it was my n75 valve. Replaced it with a grimspeed MBC. Which now allowed me to make over 5psi again but occasionally the car would try to go into limp mode causing the dash to light up (traction control, suspension, and abs). I also would get a code for maf circuit to high (p0103) only thing I could come up with was boost leak, car still ran good with the MBC and boosted just as it should 18psi stage 2. I had done a boost leak test when this first started and found a torn tbb, so I replaced that. Couldnt find any other leaks so assumed I was good. Didn't fix my issues, I just installed a fmic so figured I'd do another boost leak test, found some small leaks but nothing major. I also checked the vacum lines to the wastegate and they hold vaccum like they should. I then went for a test drive and now I can't build boost. It will maybe get to 5psi but it struggles to hold 1-3psi. I have tried hooking the n75 back up same results, I've tried driving without the wastegate vac line hooked up, same results. I've even tried driving with the vac lines to the diverters unhooked thinking they were being help open getting vac when they shouldn't. No change. I'm so confused as to what is causing this and if my two issues are even related. Turbos make 0 noise, no smoke, and were tight as of 1000 miles ago when I gutted my downpipes . Please help!

[AudiTuner1187]

Try testing your wastegates and see at what psi they open. I believe 6 psi or so. Dont put more than 10 psi or you can blow out the diphram. Make sure they open and close at same time and that they arent stuck open.

Sent from my SM-J320P using Audizine mobile app

[kaclaytor]

Try testing your wastegates and see at what psi they open. I believe 6 psi or so. Dont put more than 10 psi or you can blow out the diphram. Make sure they open and close at same time and that they arent stuck open.

Sent from my SM-J320P using Audizine mobile app

Any how tos on the process of checking when the wastegates are opening?

[AudiTuner1187]

Use regulated pressure with a guage going to waste gate, listen for a click, that will be them opening, when you relieve pressure, should snap shut. Should be able to see movement from actuator as well.

Sent from my SM-G900V using Audizine mobile app

[kaclaytor]

Wastegates appear to be functioning properly. After doing a log with vcds it looks like my ecu is not letting my throttle open past 20% to restrict boost. Anybody ever seen this before?

[AudiTuner1187]

Seems like limp mode? What's waste gate duty cycle in vag com. Very odd you can't build boost with wastegate vac lines unhooked. Can you hear them spooling?

Sent from my SM-G900V using Audizine mobile app

[kaclaytor]

I can hear them spooling and they get to 5lbs then car hesitates and boost drops until its at 0. When watching the logs my throttle body goes fron 100% down to 18-20% after I hit 5psi.

[AudiTuner1187]

5 psi is limp mode. No CEL? Scan for codes? Try unplugging MAF and see if it boosts

Sent from my SM-G900V using Audizine mobile app

[AndrewWK]

Have you done a throttle body adapt? Also electrically unplug n75 and go for a drive. Does it hold boost and to what boost level? I would expect around 6psi on k03 stock wastegates. Do you still have an n249 (please say yes). Post vcds scan results as well.

[kaclaytor]

I have done the throttle body adapt, no difference. N75 plugged in or unplugged makes no difference. Will hit 5psi but drops down to about 1psi and will then struggle to hold 1psi. I didn't delete tge n249 so am assuming I still have it.

[kaclaytor]

Picked up a new n75 and hooked it up, no more boost issues.

[TavNew86]

I just started having the same issue but it's throwing code ( p0175) . What should I do ?