'95 A6q wagon suddenly running rough

[Mike Veglia]

Yesterday my wife's '95 A6q wagon suddenly started running rough, seems to have a miss on one cylinder I think. Last night I pulled all the plugs and inspected them and the plug wires, and ran a compression test. The car has ~139k miles now. New heads were put on at an Audi dealer for the previous owner when it ingested some water in a texas flood at around 85-90k miles. Compression was up around 160 on all but #1 which read low at ~130. I hope this low reading may be caused by carbon buildup and could rise again in the future, or maybe I wasn't getting a good enough seal with the threaded fitting on my compression test set (old snap-on)--dunno. Anyway, I pulled plug wires one at a time along with injector wiring connectors one at a time to see which cylinder was missing. The culprit appears to be #4 (not the lowish compression #1). Plug wires look good--no cracks or visable arcing in the dark, but it was late last night so I didn't ohm them out with a meter yet. Plugs all looked
 pretty good (and pretty much the same) but they are ~27k miles old. I'm planning to put in a new set tonight to see if that helps. Anything common on the 2.8 V6 that causes rough running all of a sudden? TIA for thoughts and advice.
 
 


Mike Veglia
Motor Sport Visions Photography
http://www.motorsportvisions.com