Rough idle after TB change, sparks, & 90k
 

I see this may be an old subject, but was very surprised how rough the idle was after getting my car back. Car has always been very quiet and no noticeable vibration on idle. Now it gently rocks like you are in a pickup. I replaced the spark plugs with the bosch +4. Could this really make that big of a difference?. Not sure what plugs were in before- whatever the dealership puts in. Any other ideas on what could have happened during the service?

Not likely the spark plugs, but if whoever did the TB service didn't....
 

get the cam timing exactly correct then a rough idle is one of the possible outcomes. I'd take it back to the mechanic that did the TB change and complain- see what they say. If it was a stealer, they will no doubt shovel you the "they are all like that" line of bull.

Yes, my car was significantly smoother after TB change

I seem to remember some posters complaining about +4s in their A8s .. roughness.
 

I used the Search Tool, and golly if it didnt actually WORK this time .. I found the last thread on this, using "Racing spark plug" as the search term.

Could be a plugged fuel injector. Put 2 bottles of Techron fuel injector cleaner in a full tank.
 

<center><img src="http://www.mait.cz/Obrazky/chevfoto/Techron.jpg"></center><p>
Although if the problem occured after a TB change, this may not be the case.

See this older post of mine...<ul><li><a href="https://forums.audiworld.com/a8/msgs/99797.phtml">https://forums.audiworld.com/a8/msgs/99797.phtml</a</li></ul>

I have had those plugs for 2 years now and now problems what-so-ever.