Rough Engine & Shifting 2005 4.2
 

I have a 2005 A6 4.2 with 65k miles on it. At 1800 RPMs the engine has a shake that is easily felt throughout the car. Also, the transmission downshifts are quite jerky. Everything else runs great.

Any thoughts on the engine vibration or how to improve the shifting?

Has the tranny software ever been upgraded? Have you upgraded to the new tranny fluid? Did you bring the car in for the coil pack recall? Has the fuel filter ever been replaced? How long have you had the problem?

Dont know about the software update.??
Coil pack was replaced.
No tran fluid replaced. Thought it was lifetime?
Fuel filter was changed at service.

Problem has been going on for a few months. Car not driven much though.

The manufacturer of the transmission says that the luid must be changed every 50k. Despite this requirement Audi claims lifetime in order to cut down service costs. Check the transmission section of the TSB library linked in my signature for the details on the software and fluid upgrades for the tranny. Are you sure about the fuel filter being changed at "service"? Audi does not have a scheduled service that call for the replacement of the fuel filter. If the fuel filter was replaced you would have had to ask for it specifically.

Have you checked the engine mounts?

I'd start by changing spark plugs and running some sea-foam thru the engine first. I throw a can of sea-foam in mine every season or when I notice it starting to run a little rough at idle.

Not sure on the transmission, but I think that you can do a trans reset or adaptation of some type.

I just rolled 140,000 miles last week on my 05 4.2 and have never done anything other than normal plug, air filter and engine oil changes. Take that back, I changed the valve cover gaskets at 130,000 myself along with a set of Akabono? brake pads at 120,000, which by the way have ZERO brake dust. This Audi has been fantastic for me thus far. I haven't had any trans or gear case oil changes either. Hope you have an easy time finding the solution. I'm betting it will be something simple.

How exactly do you apply the Seafoam? thanks in advance

Pour a whole (16 oz. can) into full tank of fuel and drive.