When engine warm, there is still vapor coming out of exhaust. have a leak in cooling system,can not find it. no sign of water in oil.
If no fluid ifs being lost,it may be o2 sensor.Does car have any kind of skip?
Your engine coolant keeps getting low and you have to add more. If so possible head gasket issue.
http://troubleshootmyvehicle.com/gm/3.1L-3.4L/blown-head-gasket-test- 1 -- check this out
www.youtube.com/watch?v=NlT8U8D5vwQ -- is this what yours is doing? If so blown head gasket.
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