'95 O2 Sensor

[95Splorer]

Hi I have a code reader and I am pulling codes 136 and 172, this is showing lean o2 sensor. My question is how many O2 sensors does this truck have, I only see one in the Ypipe before the cat. Troubles I am having with the vehicle is that it seems as if it floods out when it's warm and at idle, I usually have to wait a bit before I can start it again and when it does start black smoke comes out. I'm pretty sure that it's running rich as hell. Let me know what you think please!

Edit engine is 4.0L OHV

 

[KPT]

It has two. One on either side of the Y pipe.

I doubt the O2 is causing the issue. I have no idea what is though....

Edit, found a pic of them for you:

 

[95Splorer]

Thanks, those are the only codes that are showing up. All I have is a code scanner so I can't monitor which one is bad..Going to replace both then. Thanks!

 

[95Splorer]

What else would make it run rich? It gets flooded out at idle when it's warmed up and won't start until the fuel in the engine evaporates, when it does black smoke will pour out.

 

[MrShorty]

So many things could make it run rich: just about anything in the engine management system (since one of the primary purposes of the computer with it's accompanying sensors is to determine proper A/F mixture), and the fuel delivery system come quickly to mind.

In your case, the computer is seeing a lean signal from the O2 sensors, but other symptoms suggest the engine is actually running rich. This suggests to me that the problem is in the O2 sensor circuits themselves: either the sensors are dead, or the wiring between the sensors and the PCM has been cut/pinched/unplugged, maybe a bad PCM ground. I could also see an exhaust leak upstream of the O2 sensors causing this condition.

 

[95Splorer]

The ECM was replaced about a month ago due to other crazy issues. It ran find until recently.
I had a friend check the volts on injectors and he said they were high, much higher than normal. I am wondering if they are dumping more fuel because of the O2 sensors, I guess there's really no way of finding out until I pull and do a bench test or to replace them..