Hi folks,

my felly vibrates in idle very heavily. What could be the reasons for it? Could a too tight valve clearence be the cause?

Could be an engine mount.

misfire?

No it does not missfire. The idle speed is stable, but I think it is too low (about 700) if I accelerate the idle speed a little by foot (to ~800) the vibrations are away. is there any possibility to increase idle speed? (via OBD?)

check that the throttle cable isn't too slack for a start, yes you can adjust the idle speed with vag-com or similar but i'm not 100% sure of the procedure

Now I know that it is possible to increase the idle speed. Via VAGCOM it is possible in steps of 10 upm... I think I will go to 800 oder 850. Today I cleaned the throttle ... will see tomorrow whether it helps. Tomorrow will go to the VW garage for checking failure memory (?) and adjusting idle speed. And I will reset the throttle settings.

I'm pretty much sure you're on the right lines (fixed throttle stop); With a movable one, I'd adjust there rather than in software.

As to the cable, make sure it is just slack with the engine hot idling.

back from the garage... idle speed is about 800 upm... very normal.

It gets no wrong air! But the idle is rough. He thinks a) ignition could be wrong (but driving is normal) throttle is wrong --> needs reset c) head gasket is gone?

I'd try the throttle reset next; ISTR the procedure is something like:-

1) Make sure you have the radio code.

2) Disconnect the battery for 15 minutes.

3) Reconnect the battery and go for a drive.

Problem solved

Yesterday I got in the car for driving home from work and it sounded like a V8... the exhaust fell apart and is not anymore at its place... the sound is great and the vibrations are much much better.