Audi A3 Sporadic Rough Idle

[A3 Driver]

Hello to all. I am new here. I had my 2006 Audi A3 2.0T FSI FWD DSG for 5 years now.

I was wondering if anyone had the same problem as me? The mechanic said it was common something to do with the turbo.

After my car is all warmed up, and driven for lets say about 20 miles my engine will idle kind of rough when in neutral. It drives okay. No misfires or CEL. This only happens when my car is warmed up and in neutral. When it's on drive, it does not idle rough. When I start it on the morning, it idles perfectly.

It's driving me nuts that I had my valve cover gasket replaced. I tightened every hose that I can. Still it's there. Sporadic.

Does anyone else had the same problem? Is this inherent of the FSI engine? Common?

Any help is appreciated.

Thanks.

My setup:

K&N Typhoon CAI
Full Turbo Back Exhaust
New Coilpacks and Denso Spark Plugs
BSH Stage 1 PCV
Unitronic Stage 1+

[Dad A3]

What's the mileage, and has the carbon been cleaned from the intake? Had the same problem with mine at about 90K carbon clean fixed it.

[A3 Driver]

Mileage is 126K

I will clean the intake with seafoam (unless there are any other suggestions) and replace the N80 valve.

Will give you a feedback. Thanks for the reply.

[A3 Driver]

Update:

Replaced the N80 Valve
Did cleaning with Seafoam

Rough idle has gone a bit but it's still there. Again when it's in NEUTRAL or PARK. When on DRIVE it's fine no rough idle. Pulls ok and drives ok.

ANY ADVICE on what to look at next? I was thinking to have it decarbonized manually by taking out the intake manifold...

Thanks.

[MurkyRivers_A4]

Update:

Replaced the N80 Valve
Did cleaning with Seafoam

Rough idle has gone a bit but it's still there. Again when it's in NEUTRAL or PARK. When on DRIVE it's fine no rough idle. Pulls ok and drives ok.

ANY ADVICE on what to look at next? I was thinking to have it decarbonized manually by taking out the intake manifold...

Thanks.

Pretty sure that's what Dad A3 meant when he asked if you had the carbon cleaning done. Seafoam will not do the trick and you will have to do it manually by removing the intake manifold. Remember to buy yourself a manifold install kit if you are planning to remove it. I have heard that the injector grommets get ruined when pulling the manifold.

[A3 Driver]

Pretty sure that's what Dad A3 meant when he asked if you had the carbon cleaning done. Seafoam will not do the trick and you will have to do it manually by removing the intake manifold. Remember to buy yourself a manifold install kit if you are planning to remove it. I have heard that the injector grommets get ruined when pulling the manifold.

Duly noted. Thank you. I will have it done soon.

[0mn1]

Check Coils, Plugs, clean MAP, and you can use BG cleaner for FP and inectors.