okay soo bank 2 senso 1r was has been going out i have replaced it three times and it will function properly for two three days then will stop responding and of coarse throw the low signal voltage code. and yet again it will role coal. soo i am at a loss i already did continuity test between the heater and the computer and also have check the signal wire to see if there is an ohm issue and there is not, i know that o2 sensors create there own voltage soo there isnt a supply hot for the sensor soo what i have collected is there is some sort of contamination getting in it but my coolant is full and has been full for the last three weeks. my fuel trim are running somewhere around 40-50% positive. idk has anyone else had this problem? if so help me out i have ran outtta ideas (and no it is not throwing a lean code)

 

Burning oil can cause bluish/black smoke. Could you have a piston ring or valve seal failing on that bank? It's a wild guess, but might explain the O2 fouling and the black smoke.

 

when i first replace the o2 sensor it doesn't smoke that i notice, like it is possible that i am burning oil and its causing it to malfunction but if it is burnin oil its not bad enough to foul an o2 sensor i havent noticed a drop at all in my oil level since i changes it 1200 miles ago. oh and the 40-50% fuel trims are just on the right bank the left bank run in the norm -2 to 0% fuel trim. and it is raw fuel coming out not oil, like legit my blazer smokes more than my buddies 7.3l

 

if its smoking that bad, I would suspect something other than valve seals. I have bad valve seals on my jimmy, and it only smokes for like a second at start up.
Have you smelled the exhaust (yeah, not the advice you would get every day) but what does it smell like?
Black smoke usually is an indication of excess fuel. First thing I would do is smell your oil, see if it smells like raw fuel. and then do a fuel pressure test.

 

Yeah, that's why I mentioned piston rings, but he says it isn't burning that much oil. I don't now much about fuel trim on these vehicles, but I'm guessing yours is high? If so, it may be fouling the O2, but it's kinda doubtful. How about injectors? Are they all running ok?

For the right bank to be so far off does seem weird. I would even hazard to guess the computer might be going bad, screwing up fuel trim and therefore the O2 sensors. But that's a long shot.

 

Is unburnt fuel and a sign the engine is running rich.Have you tryed testing any of the other sensors?

 

The thread has pics and all I suspect you have leaking full regulator and bad injectors.Remove your top planem off and look for cleaned washed areas and puddles of gas.My guess if you fix this your problems will be solved.Seems to be a very common issue.

 

My truck was smoking bad, like blown head gasket bad and throughing 02 and misfire codes. I replaced the fuel spider with the updated mfi and it runs like new.

 

that is what im starting to wonder, idk i know it isnt the fuel pressure regulator because that was my first though. and i know coolant can ruin o2 because it seals off the chemical reaction between the the hydrocarbons, but i dont notice any coolant missing.....but like im at a loss i guess ill try getting a new computer from a junk yard and see.

 

Did you do a fuel pressure and leak down test? The computer will have to be reprogrammed to your vin and have a crankcase relearn done. How old are the spark plugs?