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Originally Posted by zmanss
The car runs great, when it runs; the problem is keeping it running at idle after it has warmed up.
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When a car is cold and first started, the ECU ignors the O2 sensor signal and runs in closed loop mode, that is a preprogrammed fuel map.
Once the car is up to operating temp the system goes into open loop and takes the info from the O2 sensor and makes any changes needed.
When a O2 sensor goes bad, it gives the signal of being lean when it's really not. So at first your car runs OK because its in closed loop mode. than when your car swithces to open loop the bad O2 signal is srewing with your A/F ratio. So your way rich, that why it can idle very well, and why there is unburnt gas getting into the motor.
O2 sensor's should be changed every 60k, when's the last time you changed yours?