B7 Overboost Issues/ Fluctuating Boost

[tommyp603]

Hey Everyone,

I'm looking for help on fixing my B7 that I'm running in circles with issues.

I installed a K04 Turbo along with
-Plugs
-Injectors
-Cam follower
-Carbon cleaning
-All new intake gaskets
-RS4 clutch

Already installed
-ECS intake
-RAI high flow cat
-APR HPFP
-JHM FMIC
-034 Catch Can

I was previously running the K03 with no issues.

After i installed the K04 i had APR remote tune the car to the Stage 3 tune.

I did this early 2024 April and went easy on the turbo to break it in.

I really didn't drive the car much during the summer because i have a jeep and i was frequently driving that because we had a nice war, (rain free) summer.

Fast forward to fall/winter now and I've had nothing but issues with the car over boosting and going into limp mode.

When I roll into boost gradually it'll get up to 10-13 PSI and fluctuate between (10-13) then if i keep on the throttle it'll over boost and go into limp move.

I checked the wastegate crack pressure and its at 9 PSI.

I replaced the diverter valve and N75 valve and hoses.

I've been getting different codes from all over P 1297,1093,0234 (Cylinder misfire codes)

I checked all over for a vacuum leak with carb cleaner but couldn't find anything.

I checked all intercooler piping for cracks or tears.

I checked all around the intake for leaks.

I was going to try a boost leak pressure test.

The car idles perfectly.

Do you need the blank off plate for the turbo crank case line to perform the boost pressure test? Link here - https://www.ecstuning.com/b-40t-performance-parts/pcv-block-off-cap/vag-ea888-cap~bo/?gad_source=1&gclid=EAIaIQobChMIg7Dj5r6niwMVtFxHAR2DezGoEAQYBSAB EgKAlvD_BwE

I read conflicting things on other sites so I'm trying to do it the correct way

I'm going to do some data logging today

Boost pressure specified
Boost pressure actual
Engine RPM
Fuel Pressure
Mass air flow

Anything else i should log?

Any information of thoughts would be great as I'm loosing my mind with this car

[Audibot]

Add the LPFP pressure too. I used to have misfires at WOT on my B7.

Idk the last time you changed the fuel filter, but what I used to see was it would start at about 5.5-6 bar and then drop to below 4 bar, at which point the CEL would blink and it would misfire. At Stage 3, you may need a new fuel pump in the tank.

[Older_not_Wiser]

Add your fuel trims and individual cylinder timing pull to the log list as well, Measuring block 003, 032 and 020. Do it for a full throttle pull to redline or at least until it goes into limp mode. Might give some indication of where to focus your investigations.

Agree it could be fuel supply related, or DV and N75 plumbing related. Are you sure there are no kinks in the DV, N75 and WG flap actuator hoses?

I would also check your MAP sensor. Ever have oil in your intercooler at some point? I see you are running a JHM intercooler and a catch can so that should keep the oil in the intake system to a minimum, but how long has it been since you installed those? I have seen some that are pretty gunked up.

[Jayz691]

What turbo is it? Did you check your crack pressure correctly? 9psi crack pressure is quite high, for an OTS map.
When I ran a higher crack pressure on my CTS K04, my tuner(Motoza) had to greatly reduce n75 max duty cycle. If I got on it, it would peg my boost gauge(30+ PSI)..
You can do some data logs, but I would first try backing off on the WG. Loosen it up till the flapper is loose. Tighten till you can't spin the flapper easily, and give it 3-4 more full(360°) turns. Lock it in and take it for a ride. I'd be willing to bet that's your issue..

Sent from my CPH2611 using Audizine Forum mobile app (https://r.tapatalk.com/byo?rid=87676)