I had the same thing with my 1.8 and they were mad spark plugs.

 

2001 a6 prolly one of the power output stages on top of the airbox is bad causing one of the cylinders to misfire. but have to hook up to scan tool to figure out which one.

 

100% agreed with Mike & fasttoys. My '01 2.7L had the exact same problem & symptoms. Numerous misfires, severe jerking, and flashing CEL after pulling out onto a highway doing 60mph. First thing I checked was my spark plugs & their gaps. All was good. Observed my coils but wasn't sure as they seemed fine. Then tested my ICMs (Ignition Control Modules/Power Output Stages - both the same). There are two of them on top of your air box. As always, get the codes read before anything. The car will tell you it's sick and why. Then, after seeing the numerous misfire codes, test your ICMs. Unplug both of them, and swap the wires for one, with the other. Reset your codes. Restart the engine. If you're misfiring, it should do it while idling. Do NOT drive with a flashing CEL. Now, compare the new codes with the ones before switching the ICMs. If one ICM is bad, the codes will follow that ICM (if you had a misfire on #4 before, it'll be a misfire on #2 now.) If both ICMs are shot, start shopping eBay lol They are expensive parts and I got a wonderful deal there on aftermarkets and to this day I have not had any problems. G'luck!

 

had the same issue on my a6 and it was a bad wire. impossible to see just looking at it. it was internal and i went through everything trying to find it. sure tell sign is pull the plugs. inspect each one. is one or more fouled? one plug fouled = replace that wire.
multiple plugs fouled it something else.......coil pack, maf, etc..... (above posts)

 

Had the same symptom on my 02 A6 2.7t 6MT. Codes came up misfire on cylinder 3. I went on ebay and bought a set of OEM coil packs for $150 from a low mileage S4 that had been totalled. I checked the part numbers and all is the same. After swapping the one bad pack, no issues since. If you are interested I would be happy to sell one or two of them to you if you want to give it a try. If you are getting multiple cylinder misfires I might suspect the chipsets on the air box. Shoot me an email at reaper6060 at AOL dot com if you are interested in the coils. Good Luck!!

 

I changed the grade of oil on my 2.7T from Castrol Edge Sport (10w-60) to Castrol Edge(5w-40) and the oil light started going on after 1500kms. The oil is also heating up to
130C, but the car is not overheating. The dealer says the oil is breaking down and needs to be changed. Can this be true and what else can cause this?

 

Anything could be true on an Audi.

Castrol Edge Sport (10w-60)????

Unless your engine has 2mm tolerances on the crank and other shafts I'd be very surprised your engine got proper lubrication.

130C on the oil - sign of high internal friction.
The dealer's explanation is a BS.
Have you flushed the engine between the oil changes?

 

I had this happen on mine for quite some time and it ended up being the main air intake hose has disconnected from the intake right under the plastic Audi cover that goes over the back of the intake and vacuum hoses. So basically the car was breathing through that 1 inch gap of the loose hose and bypassing the MAF sensor etc.

 

Can overfilling the oil be a problem that causes this?

 

Anyone tell me what the Oil Pressure switch purpose is on a Audi A6 2.7T Allroad?