I have been working on this problem for a while. So are a lot of Audi and VW owners. I have read no resolutions yet.
It's long winded but if you have this problem I'm sure you won't mind.

Problem;MISFIRE ON CYLINDER 4-COLD START.
when car is cold; outside ambient temp below 70 cylinder 4misfires 17-29 times for ~20 seconds then runs fine. When the temp is above 70 or car is warm it starts and runs fine. This happens every morning. I noticed the difference for ten mornings it was 72 or above here in Florida and it started fine.( I stupidly though I had fixed it)

Auditech79 said it's sound like a ECM issue, AND IT IS.
I also dicovered a TSB for a 2.7t that outlines a similiar problem due to a ECM glitch,it was resolved by flashing the ECM. However Audi is being a bunch of cornholes and won't just flash it for me (my money? go figure) they want to diag it themselves (suuuure they do). So I'm looking for the smoking gun now. I want to know exactly what this damn thing is doing and where and when it is screwing up.

The coils and plugs are new and injectors cleaned tested and every thing has been swapped. The wiring and connections are good, vacuum system tests good and lines are new, fuel system is good, filters all new.

At below 70 degrees outside temp or MAF/IAT reading of 30C or below (must be the threshold for the ECM) the ECM starts the car in OPEN LOOP and enriches the fuel to each cylinder and retards the timing. I used unisettings and shut down the fuel enrichment on WARM UP to 0% and the misfires stopped completely. At 70 or above the ECM starts car in closed loops and misfire does not occur.

I also did the best I could to clean the intake chambers through the injector holes because I read Audi was cleaning the Intakes with the heads on the engine and getting results. If it is the valves I would have thought the exhaust would be the problem. The intake chamber was dirty but not caked up (they shouldn't be anyway because the gas cleans them). I obviously can't check the exhaust valves without pulling the head but we all know they are sure to be messy but I have know idea if they are the problem. I later received reply from a guy in the UK who had the heads ported and polished and said it was a waste his problem persists.

I am still working on the permanent solution/cause. It is a fuel related or combustion issue due to fuel enrichment in open loop. I actually think the ECM is giving Cylinder 4 injector too much fuel on OPEN LOOP. The problem persists on every percentage setting except for 0%. This car runs so smooth on closed loop you would not even know it's running. Could be a glitch leaving it on entirely

With the WARM-UP Fuel enrichment set to 0% it did not misfire this morning. So it is the ECM's fault on open loop. Since it didn't misfire on Open loop this morning I deduct that the timing and spark are OK on open loop. I will continue to test the actuation of Cylinder 4 injector, relative to the others. (I think that is the problem)

I have not turned the enrichment back to 100% yet to see if the intake cleaning made a difference. I only get one shot a day unless I trick the MAF by cooling the intake air. I would rather see it on normal cold start in the morning.

I'll keep you posted, I'm getting close now.

I really wish I could flash the ECM myself.

If you have had this problem/misfire on cold start only let me know.

If you know how to monitor the injection period per cylinder with the Vag-Com Let me know.

 

Is there a possibility that the number 4 injector is not up to specs anymore?
Can you swap the injector with another one and see if the misfire still persists on the same cylinder?
Or maybe is that particular intake valve causing the ECU to enrich the fuel for that particular cylinder?

I'm just hypothesizing; probably I don't have a good basis for my rationale.

 

I have switched the injectors twice and problem persisted.

It went away when I turned off the enrichment on start-up so it is no longer adding extra fuel on start-up.

The open-loop is a pre-set the ECM uses so I don't think it adapts to it.(I could be wrong maybe it modifies it) Once the ECM switches to closed to loop it uses reality to adapt. So I don't think that it is adding fuel in Open loop to compensate for compression loss.

But if the ECM does modify Open loop pre sets that could be another issue. I'll look into that.

I am definitely down to injection period or exhaust valves. I tend to think it's injection from the looks of the plug and cylinder. If it was the exhaust I would have lost compression and the plug would be carbon fouled. It's clean. And going on the assumption that Open loop is pre-set and not modified by the ECM then if it was a valve issue the misfire should persist even with enrichment set to 0% because the ECM can't adapt until it switches to closed loop.

The only reason I was willing to go by way of the Intake valve cleaning is because I read Audi/VW was getting results. I figured maybe there is carbon build up happening within the intake chamber slowing fuel flow enough to cause this. It was dirty but not that dirty.

So far I can't figure out hoe to monitor all of the injectors via VAG-COM. I'll keep reading.

At least my CEL turned off and I have the misfires contained for now. I could just leave it set to 0% it rarely gets colder than 60 here in SWFL. But I am on a mission.

 

Well 'closed-loop' is not completely 'closed'. It takes the O2, Speed Sensors and what not out of the picture, but the Coolant Temp, OAT, IAT, Fuel Pressure, etc are still used to give the quickest start and then quickest warm-up.

 

I think you meant to say Open loop.

I had 4 misfires this morning on CYL 4 so that's better than 29 (725% better)

Now I turned down the start up fuel enrichment to 35%

So
warm-up/cold start 0%
Start-up/ any start 35%

Since the misfire is just about gone and the car is starting fine. I'll keep tweaking and monitoring the injection time and IGN timing at each phase this week. I'm making a comparison chart so I know what it is doing when it is running smooth and what it is doing when it's misfiring.

Next weekend I'll pull the fuel rail and test the injectors into clear test cells to see if cyl 4 gets too much. If not than it is most likely a valve issue and I'll pull the heads in July.

No matter what I do I seem to get the best test results in the morning. I have trouble tricking it. I'm going to order another ECT and put it in a glass of water. and two bags of ice on the intake tube. That will speed things up so I have a longer test window.

I read another thread Audi or VW did the following on a 4cylinder Guy said it's working but He is in Florida too.Let's see what happens when it gets cold again. seems like they're replacing everything. I guess that's got to solve it right.
1) TSB for cold start misfires, replaced all 8 exhaust valves, upper valve cover gasket
2) replaced high pressure fuel pump
3) replaced high pressure fuel pump control unit
4) removed intake manifold and cleaned all exhaust valves, cylinders 2 and 4 were supposedly nasty, cold start misfire was on cylinder 4

I swear I am studying this **** night and day it's turning into an obsession. I need to hit an Audi-Aholic's Anonymous meeting.

 

3am reply... My story and I'm sticking to it!

 

I cleaned out the intake chambers and backside of the Intake valves I'm sure soaking for 2 hours in sea foam got them good as well as the seats. But it had no effect on the cold start. It did however smooth out the ride and idle the car no longer accelerates like mear regular automobiles it glides and soars. Wow what a difference. At least I got something from it. For the 10 dollars I spent it was worth it.

I am going to pull the fuel rail up tonight and stick each injector tip into a seperate test vile, turn the warm up and start up enrichment back to 100% and leave it till morning then I'll see tomorrow morning if no. 4 is getting more fuel than the others.

 

Dude.. lotta work

 

OK here’s the latest data on Cold Start Misfire Cylinder 4

HERES A RECAP

Vag com shows 28-30 misfires on cylinder 4 only.
Problem only occurs for 10-20 seconds on cold start; first start in morning or sitting for 6 hours. Car runs perfectly after 10-20 seconds and will restart fine when warm.


Coils, plugs, new and swapped around

After changing all of the Vacuum lines and moving crap around it went away for ten days
During those ten days it was above 70 overnight.(no idea if this means anything)

After Sea Foam treatment crankcase and Intake and Oil/filter change it came back.
I use 0W40 Mobil 1.

I tested the injectors they are all putting out the same amount of fuel.

ECT/IAT seem to be working fine they register the temp fine.

Throttle valve alignment didn’t help.

Cleaning the Intake valves/chambers did nothing for cold start; I do feel improvement in acceleration though.

HERES THE NEW

If I adjust the warm up enrichment to 0% I only get 4 misfires on cold start instead of 30.

I was testing the compression again today 3 tests per cylinder.
The fuel rail was off so no fuel in the cylinders

I put everything back together and it started the best ever.
I did not hear the valve chains slapping, they had pressurized.

So the only two things occurred while cranking vacuum and oil pressure.

I’ll rule out the vacuum tomorrow morning by creating vacuum before I start it.

I am liking the valve chain adjuster for this now. Could it be that the channels are blocked it works fine once pressurized.

Would the knock sensor be hearing the chain slapping around and mess with cyl 4, Vag –com does not show it is retarded.

Cylinder 4 compression 197- I tested this again it’s 197-200
Cyl 1,2,3,5,6 all are between 187 and 189

While researching this I have noticed that when this exact problem is experienced it is on cyl 3 or cyl 4.

I will now retire to my manual and learn everything I can about the chain adjuster system.

 

Well i wanted to save this for the very last but if you're up to it, i want you to remove the intake camshaft. Look at the lifter bucket and cam lobe VERY carefully! Cam shafts have been KNOWN to wear on the lobes, holding a cylinder open/closed just long enough to mess with the ECM. Out of a total of about 200+ misfires i have diagnosed on a 3.0L, 20 of them had bad cam shaft/s. Most likely due to using poor oil and poor maintenance practices by the previous owner. I hope to GOD this isn't your problem, however i still believe its the ECM.
If you can manipulate the dealer to flash the ECM for you or call AOA about the possibility of a 3.0L flash then this is the only other diagnostic path i can send you on...