Could be time for a tune-up. It sounds like one cylinder is not firing. That can be caused by a fouled spark plug, bad ignition wire, leaking injector. Depending on how long it is run over-rich and how old the O2 sensor is, Yes, it may need to be replaced. I don't think the O2 sensor is the cause of this but it can definately be damaged by being dunked in unburnt fuel. David Teitelbaum vin 10757 --- In dmcnews@xxxxxxxxxxxxxxx, "Lee Edmonson" <lpedmonson@...> wrote: > > Okay, so #02566 (automatic) on the Oregon coast has been running just > fine on its weekly outings until recently on a cold (for the coast this > is near 32 F) day when I started it normally, and while letting it come > up to temperature in the garage it started running rough while doing > its normal idle hunting. This roughness includes lots of black smoke at > every RPM. I have read through many of the old posts about causes and > cures and did not see an obvious clue as to what could change sitting > in a garage for a week. > This morning it would barely start and is very rough at idle with black > smoke. I did not let it run very long in this condition, but probably > had a total of 5 minutes of rich mixture and smoke. The second time I > tried to start it today it would try to start, but would not quite make > it. Has the O2 sensor been killed by the rich mixture and should it be > replaced before moving on to other things? Where is the best place to > start running down this issue? > Lee Edmonson > Vin #02566 > ------------------------------------ To address comments privately to the moderating team, please address: moderators@xxxxxxxxxxx For more info on the list, tech articles, cars for sale see www.dmcnews.com To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/dmcnews/ <*> Your email settings: Individual Email | Traditional <*> To change settings online go to: http://groups.yahoo.com/group/dmcnews/join (Yahoo! ID required) <*> To change settings via email: mailto:dmcnews-digest@xxxxxxxxxxxxxxx mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx <*> To unsubscribe from this group, send an email to: dmcnews-unsubscribe@xxxxxxxxxxxxxxx <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/