Bank 1 O2 sensor #2 0volts?

[dirtydave289]

I logged my o2's since my car has a misfire and stalls sometimes. I got 0v on bank 1 sensor 2 so I pulled it out..it looked beat to HELL..bent and dinged up (cats pooped out their insides a while back) so I've been attempting to test for continuity between the wires but I can't figure out where all the o2 sensor wires go. they turn into a bundle and i can follow the bundle up around the bellhousing but I lose them at the top.

Any ideas on how i should approach this?

 

[TVSCobra]

The post cat o2 sensor are only there to monitor catalyst efficiency.

 

[dirtydave289]

I have an amazon tune and Rick has been helping me diagnose my running issues and it came down to this o2.

Bank 1 sensor 2 would be the post cat sensor right? I don't see how I could have an issue in the single o2 sensors wiring but none of the others or no other wiring issues on the car..but i guess it's possible. Is there any other reasons it would read 0v?

 

[TVSCobra]

If its reading 0volts you can have a wiring problem, a faulty sensor, no power to the sensor, etc. If the cat has gone south then you will usually see it "switch" like the precat sensor. Does Rick have the rear o2s turned off? Have you tried swopping the precat 02 sensors?

 

[dirtydave289]

What do you mean by 'switch'?

The cats are gutted if that makes anything different. I'm sure rick would have said something if he had them turned off. all other o2's are giving voltages to the pcm so I figure that one should too. What will swapping the precat o2's do? Sorry for all the Q's Im just clueless as to what I need to do. My cobra has been down for almost 2 months now I'm having withdrawals!

 

[TVSCobra]

Most cars have narrow band sensor meaing they can only measure accuratly around stoich A/F (14.7 to 1) these sensors operate on a 0-1 volt scale. So they will switch back and forth from usually .1 to .9volts or so. The post cat o2s will stay and no switch if the car has cats on it and if they are working correctly.

 

[dirtydave289]

My cats are just hollow so should they stay then? My bank 2 post-cat sometimes reads 0 (around idle) but will start giving a voltage above idle and sometimes off and on at idle. Bank 1 sensor just stays at 0 no matter what. Why is it that bank 2 reads but bank 1 doesnt? shouldn't both be showing similar readings?

 

[TVSCobra]

The efficiency of catalyst operation is determined by evaluating the oxygen consumption of the catalytic converters using the pre and post oxygen sensor signals. A properly operating catalyst consumes most of the O2 (oxygen) that is present in the exhaust gas. So the rear 02s should be around .7 to .8 volts, if you had cats. Since yours are hollowed out the volts should switch between .1-.9 volts since you don't have cats. They should be close to what the pre cat 02 sensor reading. A faulty rear o2 should not cause a driveability issue.

 

[dirtydave289]

Ok fair enough lol. Do you know how to determine if a precat o2 is bad with logging? Rick told me to log long term and short term fuel trims as well as the o2 voltages and he would see. Well he ended up having me check out the 0v o2 and the other 3 kinda got pushed to the side. If precat o2's would cause driveability issues how can I test those?

 

[dirtydave289]

Swapped precat o2's and still get readings from all 3 except the bank 1 post cat.
So stuck!

 

[sonicblucobra]

I'm having this same issue as we speak, what was it??

 

[jimc04]

my car does the same thing means nothing for performance my car runs perfect.

 

[dirtydave289]

Never did figure it out. Unless it figured itself out. I just found it while lookign for another issue and after I solved the other I forgot all about this. I may go datalog later to check my precat O2's because 1 is on it's way out and I'll see then if the post cat's are dead or working.

 

[sonicblucobra]

Let me know what ya find. Like I said this one is doing the same exact thing. Run for about 1 minute great. Then runs rough between 1500-2000, clears up @ higher rpms but you can still feel it.

 

[alexgg2]

Let me know what ya find. Like I said this one is doing the same exact thing. Run for about 1 minute great. Then runs rough between 1500-2000, clears up @ higher rpms but you can still feel it.

Has anyone figured out the problem and solution to this. I recently started receiving this code on my 04 cobra only at cold start ups but not all the time. mine also runs rough between 1000-2000rpms. Feels like a misfire and sounds like its going to die out but i dont get a miss fire code, it says O2 before cat bank 1. I switched left and right O2 sensor to see if it was a bad O2 sensor and its not because code still pops up after clearing code a week later saying O2 before cat bank 1. This started happening 2-3 months after install of Kooks Long Tube headers and Kooks catted x-pipe. Not sure if this has anything to do with it. Im assuming maybe the O2 sensor is not getting hot enough to operate correctly making it run rough at cold starts because car runs perfectly once warmed up and check engine light dissapears after a few minutes of driving . Theory sounds correct to me but it might be something else becuase it didnt do this the for first 2-3 months after header and x-pipe install. My old exhaust was oem manifolds, o/r x-pipe and flowmaster catback and it never popped a code and it didnt have cats to warm up O2 sensors fast enough on cold start ups. Im going to be changing spark plugs soon to see if this helps any and gap them to oem specs, current spark plugs have about 30k miles on them. I also do have O2 extensions on front O2 sensors so going to switch them to see if one is bad and clear codes again. If code pops up on O2 bank 1 again then im out of solutions to pin pointing problem. If anyone has figured out solution please chime in....

 

[Quagmire]

Rear 02 sensors are used for trim and fuel adaptations in close loop, fueling. Switching sensor means you know if you are lean or rich, how much is another story.
Also they are used for cat mon, heating and oxygen storage capacity.
If you are reading 0 volts there is a short to ground somewhere.