hey guys, i am having a very strange problem......it started smoking black with a really bad smell and very low mileage. it gave a code for my o2 sensor which i repaced....then the truck ran fine for 2 hours...then black again.....i replaced the sensor again thinking it had a defect....then it ran good for 2 days almost...then same problem....so what are the chance to have 2 OEM sensors defective.

so we started (the mecanic and i) looking if my electrical wiring from the sensors were fine, everything from theTPS to the ECU. everything is normal, we did a smoke test on my vaccum system and everything is good....now i'm getting a code p0171 ( lean bank 1 air/fuel) and i don't wanna run it anymore so i crap my cat.....

any idea, is this happened to anybody? i don't have any clue and ran out of idea where to look....should i really buy a third sensor again (they ain't cheap)?????

so this is for a 2000 dakota 4x4 club cab, v8 4.7l engine.....

thanks for the help
pat

 

Did you replace the upstream & downstream O2 sensors? or just one?

 

only the upstream one since the downstream sensor has nothing to do with the fuel/air mixture but more for the good fonctionning of the cat.....