A6 / S6 (C5 Platform) Discussion Discussion forum for the C5 Audi A6 and S6 produced from 1998-2004

Rough idle and white smoke

Old 02-12-2013, 01:37 PM
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Default Rough idle and white smoke

Hey y'all, I'm new to this forum and I just purchased a 2001 Audi A6 2.7t Quattro. About a day of two after I bought it I noticed that there was a rough idle and the engine seemed to "buck" at around 55-60 mph. Fast forward a couple days and the idle seems to have gotten worse and the bucking is more prevelant throughout all speeds. I went to O'Reilly's (auto parts store) so they could pull the code and the code was P0305-Cylinder 5 Misfire. I went home and pulled out the spark plugs. The plugs didn't seem damaged or clogged, just worn out. I noticed that there was oil in the spark plug bore on cylinder 5 as well as the adjacent cylinder. After that I replaced the valve cover gasket on that bank and the rough idle is still there and now there is white smoke coming out of the rear of the engine where the turbos are located. If anyone can tell me what is going on it will much appreciated!
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Old 02-12-2013, 02:19 PM
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Switch the coil pack from cylinder 5 to another cylinder, clear the codes, and drive the car. Scan the codes after 20 minutes and see if the misfire moved. If it did, replace the coilpack. If it didn't, you'll have to dig a bit deeper. Make sure the new plugs you get are gapped @ .028, and replace the coil on plug boots as well (especially if they were soaked in oil!).
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