Misfire or Sputter on Cold Start / Idle

[ghost-rider]

Hello guys i got a 06 MS6 wich started some issues last year in summer.

The car is Misfiring or Sputtering on cold starts, which seems to cure mostly after the cold start procedure.

After that i get couple small backfires on idle, on a stop or redlight.

Definately on Cold Start the worst.

The car is lightly modded and got a pro Tune with the Accesport on it.
No Engine Codes are shown, sadly.

Mods are shown in my signature.

Already changed following parts:
-injectors cleaned with Upgrade gaskets
-All Spark Plugs (SILTR-6A7G) and Coils (also NGK)
-Intake Manifold and Throttle Body gasket PTFE
-Exhaust Manifold Gasket, and both Gaskets on Turbocharger
-Coolant Temperature Sensor
-PCV Valve

Vaccuum seems perfect, fuel pressure also and there seems no Oil in the breather hoses, like if there are broken ringlands. Tested the Compression on cold engine which is 130-140 psi across the cylinders.

Cylinder 2 doesnt react as much as the others, when ich pull the Plug on the Coil unforunately so it seems to run on 3 cylinders only.
Surprisingly it drives without feeling an issue.

I found lots of similar Threads over the last year till now but no real answer or solution for this problem.

For reference i would take a thread from a member here, which also made a couple videos.
Puff of blue smoke and engine stutters

Furthermore i attach an cold and warm starting logfile.

Hopefully you guys can help an hopeless guy from germany.

greets

[djern]

did you check for boost leaks? is your VTCS deleted? not having that in your car will cause random misfires on cold starts for sure.

[ghost-rider]

yeah i disassembled and assembled everything and put silicone hoses with t-bolt clamps to be sure.

It not VTCS deleted, i checked the grommet unter the Vaccuum chamber and the hoses are good too. Flappers move easily by hand.

I dont see a leak in the STFT too