2003 A6 3.0 with 115k and Tip. Missing idle similar to issues seen on other posts, but doesn't seem exactly the same. Been experiencing random dip in RPM (900 to 800 or so) at idle. Occurs in Park or Drive. Doesn't happen under acceleration, but do notice slight hesitation (every once in awhile) if I take foot off accelerator, coast, then hit the accelerator again.

Have taken into dealer and no codes are showing up....they didn't really have any ideas either. Hadn't changed plugs, so tried that, but problem still occurs. No CEL showing up.

Any ideas?

 

Ever have your fuell filter changed? It's not an obvious maintenance item but it could be partially clogged. Ditto for air cleaner. Next guess is fuel injectors may be a little clogged. I regularly run (cheap) fuel injector cleaner through one tank of gas every 1-2 months. It's basically just petroleum distillates (whatever than means), but I'm at 135k with no hesitation. There are guys on here who swear by other oil treatments and injector cleaners, so do a search.

After writing the above, I would think a miss would throw a code based on my daughter's A4 3.0 occasonally having a CEL after a palpable engine miss. It usually goes away in a week so I have been ignoring it until becomes more frequent (it has only happened 3x in 7 months).

 

Just got a CEL this afternoon, but may also be due to a recurring issue I have with something with the emissions (probably catalytic converter, so that will have to wait until inspection time).

Had the air filter replaced with plugs, so that's not it. Is fuel filter something I can do? I'll look into it.

I can have the current code checked, but will also run some fuel injection cleaner through. However, wouldn't I notice dirty injectors under any type of engine condition, not just at idle?