Nissan Repair: Rough idle/stalling, vacuum leak, o2 sensor

Question
I don't know if all these problems are related but here we go. I own a 2001 Infiniti I30.My SES light is on and it went to Advance and the guy told me that the rear O2 sensor was not reading. He said to check the wires and if wires were in tact to replace it. My other problem is when starting the car after it has been sitting a while, if I don't race the engine it will bog down and shut off. Sometimes when I do this I get a pop like there is too much air or vacuum leak and not enough fuel. Also when the car is bogging down you see the lights go dim as it tries to stay cranked. Could all this be O2 sensor related or could I have electrical problems also?

Answer
Vichon,

The oxygen sensor not reading correctly will make the engine do strange things.  First, if it throws the car into limp mode the car will run really rich and mileage decreases badly.  The lights going dim is due to the engine getting really slow and thas alternator not being able to keep up with the charge requirements of the car.  I would change the oxygen sensor first and reset the computer.  You could take it back to the parts store and they could reset the codes or you can disconnect the battery for about five minutes to do the same thing.  The stumble and pop at startup could very well be the oxygen sensor so change it and reset the computer and email me back.