17963/P1555/005461
Boost Pressure Control: Upper Limit Exceeded Possible Symptoms: Reduced power output Limp mode
Possible Causes: Boost Pressure too HighHoses/Pipes incorrect connected, disconnected, blocked or leaking Charger Pressure Control defective VNT (variable nozzle turbo): nozzles stuck

Solenoid Valve for Boost Pressure Control (N75) defective.

Possible Solutions:,Check Hoses/Pipes to/between Components Check Solenoid Valve for Boost Pressure Control (N75)

Check / Clean / Replace Charge Pressure Control
Check / Clean mechanism for variable nozzles

So what I just did was a timing belt service. New WP Thermo Belt all timing hardware. I cleaned intercoolers good. Cleaned throttle body.Cleaned MAF sensor (2000 A6 2.7 w/Bosch) I modded air box with pipercross high flow filter and drilled a whole in airvox where OEM RS4 airbox has a secondary port n valve.

I also deleted the SAI system. Plugged up Kombi with block offs. Codes out the SAI pump. Plugged vac lines to kombis. Worked great no codes. I also switch over to Brk7e plugs at .028 and I check timing in group 93 and I'm 2*kW and 1*kW so I did good with lock bar n no lock pin.

Anyways I was reading about the springs in my 007s might be too strong considering have them installed when boost pushes on bottom of valve like most cars. And I loweed the spring n took spacer out and the lowest spring acted strange. I'm busing a NVR Stage 2++ 93 oct file and I could feel them dv pop open. So I came home put the highest spring in with a spacer called it a day. Car boosted great.

Then the next day I swap out upgraded y boot for stock y boot cause I wanna go stock engine cover again. This time it ran a lot smoother with stock y boot then before but this modded NVR file n it runs good. But thing is boost pressure sensor in boot is hose clamped on since I lost the nuts n bracket to rebolt it to throttle body. I check a lot of vacuum hoses don't find leaks. MaybeMostly ones I touched and was around during my service But a bad y boot could do it.

Or maybe its the tune. I believe over boost limit in this tune/file is 275 or 375. I noticed to remove it people put 12xx something. But here's the thing. It pulls boost. Like wtf. Then u get off it. Hit the gas spools up n takes off like normal. It do it once. Then acts. fine. What on the car should I be looking at and where the tuned file should I be looking.? I have no other ever engine dtc's ever.

I'm sorry no logs. Cause it does it randomly and I come home and read p1555. Basically since yboot install and it looks 100% in perfect shape. My silicone one don't allow me to keep v6 biturbo cover on and I painted up the intake pipes nice and like the stock look under the hood.

Any ideas please let me know. Also if I log MAF can someone take a look at it to see if this MAF is good. I got it used off a friend car had 80k. I get worse gas mileage with newer MAF then the old one thatm blew out and read 4'ish all the time.

Or any blocks/groups I could be looking in or logging.

Thanks.

at least post some fuel trims or something...