Taurus runs poorly when warmed up - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

bettywilson4 · 02-22-2008, 12:34

99 taurus duratec 120k. At first it would stall out in idle & service engine light on. Replaced the front two 02 sensors & found & fixed vacuum leak(phlegm). It no longer stalls in idle. However, now it runs rough after going 20 miles, uses excessive gas. Service engine light on again. Scanner shows one back 02 sensor and engine running rich & lean. I then replaced fuel filter& TPS . Should I replace the one back 02 sensor. One ford mechanic told me the back 2 O2 sensors have nothing to do with the performance of the car. Please help

**tbird100636** · 02-29-2008, 18:33

Quote:

Originally Posted by bettywilson4

99 taurus duratec 120k. At first it would stall out in idle & service engine light on. Replaced the front two 02 sensors & found & fixed vacuum leak(phlegm). It no longer stalls in idle. However, now it runs rough after going 20 miles, uses excessive gas. Service engine light on again. Scanner shows one back 02 sensor and engine running rich & lean. I then replaced fuel filter& TPS . Should I replace the one back 02 sensor. One ford mechanic told me the back 2 O2 sensors have nothing to do with the performance of the car. Please help

You say front O2 sensors were replaced. Do you mean the upstream ones??? I know on a Chrysler the downstream ones do factor into the fuel trim for emissions besides the normal function of seeing what the cats. are doing. What's the exact code you got??? The P---- number.