NefMoto

2010 S4.

Always (since owning) has some idle hiccups after first starting.
Also seeing these codes (not sure if related):
6322 - Air Intake System
P307A 00 [109] - Flow too Low
6307 - MAP/MAF <-> Throttle Position Correlation
P0068 00 [237] - -

How to troubleshoot?
What might be causing the symptom (idle) and codes?

Car now has smaller supercharger pulley and stage 2 tune (but symptoms existed before).
I did not find a leak when smoking the engine (through intake).

During my tests and never as stock i hit on this error and it was 100% software related (in my case) are you sure car had no stg1 before again with this issue?

+1

It did NOT have this CODE, but it had the same symptoms (rough running after first start, noticeable hiccups (with accompanying rpm drop every 10 sec for a minute or so).

Could the code and cold start hiccups and rough idle be attributed to intake valve carbon build up (like i have seen and addressed and a lot of 2.0T engines)? Car has 80k miles, had mechatronic problems (fixed), uncertain maintenance history.

So guess what...You have 2 different problems...

First of all your tune is not working and that is bringing you to a safe mode situation.

idle problems usually come from air leaks / bad sensors and some kind of hardware issue

4 steps.

1.Make you car stock
2.Fix the first issue "rough idle and such"
3.Get a proper tune.
4.Flash and run happily ever after.

Your engine platform apart from an oil pressure sensor issue and some bad compressor clutches is bullet proof if you take a good care and do the services in time. Have seen more problems gearbox related.

I smoked (leak test) the car but could not find a leak.

I suspect the issues might be related. At least from my experience with carbon build up on intake valves on 2.0T engines, rough idle, longer cranking, cold start (+ misfires, reduced power (from reduced flow)) can be caused by carbon build up. Can someone comment how common this is on the 3.0T?

It is common on all engines with out mpi/pfi injectors...Especially VW ones after 80.000 km this issue gets worst and worst but you will not fill all this problems until you reach 130.000 140.000 km or more.

a) What are mpi/pfi injectors? What injectors is the S4 using instead? Why are the "non mpi" injectors causing problems?
b) How can the code get worse? Or is the rough idle/hiccup getting worse?
c) Why do I "not fill all this problem" until 130k miles?
d) How to FIX the problem if the injectors are causing the issues? Replace with "mpi" injectors (whatever those are). Part number? Brand? Size? Style?

pull the supercharger off and walnut shell blast the intake valves to clean them.  also while you are in there remove and replace the PCV/ Breather assembly and thermostat.  these are common problems with this engine.  

Also check the operation of the intake manifold flaps with a vacuum pump.   Make sure there is no leak in the hoses and the solenoid is activating. improper flap operation can cause rough cold starts.

So carbon build up on intake valve (and/or other intake components, flapper), like I have seen lots on 2.0T (I clean by hand with scraper, brush and home brew cleaning fluid)?

a) Normal/ common/ non direct Injectors that are not used for high pressure or direct cylinder injection.
b) Because you probably have your pcv broken
c) Something broke down at that point.
d) do a proper diagnosis and if you can not do it yourself visit someone who can.Stock injectors are fine.

ps. The dtc you get on higher rpm does not have to do with the pcv valve. Revert car to stock and test.