Quick intro:I have a '01 A6Q 2.8L with 92k miles on it. My car was stuttering and misfiring slightly so I took a look under the hood. Found a broken PCV hose. Ordered a new one and new plugs. Also Seafoamed the engine since the broken PCV hose was full of gunk. While waiting for the new hose, i used a piece of hose to temporarily fix the broken one. I believe this clogged the hose and resulted in oil leaking from the oil cap all over the engine.

New hose came in. Installed it and the new plugs. Took the car to the car wash and washed the engine from the top and bottom with the sprayer. Car ran fine there and back.

Today, car is misfiring on cylinders 2 and 6, CEL is on and blinks when the car misfires. Ive checked all vacuum hoses, wire connectors, hoses, plug tightness and wires; I can't find any visible problem Here is what I could get from VCDS-lite. Any help you guys could offer to help figure out what's going on would be awesome.


VCDS-Lite Version: Release 1.0
Sunday, 11 July 2010, 18:22:25.


Chassis Type: 4B - Audi A6 C5
Scan: 01,02,03,06,08,15,16,17,18,34,35,36,37,45,55,56,57 ,65,67,75,76,77

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Address 01: Engine Labels: Redir Fail!
Controller: 3B0 907 551 BA
Component: 2.8L V6/5V G 0003
Coding: 07252
Shop #: WSC 02325
8 Faults Found:
16805 - Warm Up Catalyst; Bank 1: Efficiency Below Threshold
P0421 - 35-10 - - - Intermittent
16815 - Shareware Version. To Decode all DTCs
P0431 - 35-10 - Please Register/Activate - Intermittent
16684 - Shareware Version. To Decode all DTCs
P0300 - 35-10 - Please Register/Activate - Intermittent
16690 - Cylinder 6: Misfire Detected
P0306 - 35-10 - - - Intermittent
17927 - Shareware Version. To Decode all DTCs
P1519 - 35-10 - Please Register/Activate - Intermittent
16826 - Shareware Version. To Decode all DTCs
P0442 - 35-10 - Please Register/Activate - Intermittent
16686 - Cylinder 2: Misfire Detected
P0302 - 35-10 - - - Intermittent
18010 - Shareware Version. To Decode all DTCs
P1602 - 35-00 - Please Register/Activate
Readiness: 0000 0000

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It's dangerous to wash an engine, it often puts water just where it can do its worst. I think you may have water or just moisture in the plug wells, take a look.

 

Ah. Thats what I love about the forums, people come from different angles. I never even considered that. Thanks for the tip, Ill go check that out.

 

Problem solved. Thanks oldmots. There was water in the spark wells. I never even thought it could get down there, guess they arent sealed as tight as the bolt down 1.8t coils.

 

Good to hear you found it.
I usually wipe down dirty engines with paper towels soaked in a little kerosene, then switch to paper towel soaked in Armor-all for the finish. These products will clean safely and leave a protective coating. I save the water for the plants.