Ok,I use a aeroforce interceptor scan gauge.
Seonsor 1 bank 1 is reading 930mv-960mv when car is full operating temp and idle. It dose change when the fans come on though. Also I have seen roughly 50mv-950mv when car is started. I think thats normal correct?

Now sensor 1 bank 2 is a different story. Its reading 430mv-450mv and staying 440mv-450mv most of the time. What can you tell me about this?

Codes I have on the car are pretty much normal for headers...
p0140
p0160
p1133
p1153
p0133
Can someone school me a little on what I should be seeing o2 in mv?

 

I switched the 2 o2 locations. The mv #s stayed the same and didnt follow to the other sides. Also to make sure I did swap them I swaped them once again and still same result.So it cant be the o2 sensors.
Cant be the extentions either...im using bosch 13111 vette o2s with long leads so there is no splicing or extentions.

 

Here is a quote from an article " In many cars, the computer sends out a bias voltage of 0.45 through the O2 sensor wire. If the sensor is not warm, or if the circuit is not complete, the computer picks up a steady 0.45 volts. Since the computer knows this is an "illegal" value, it judges the sensor to not be ready. It remains in open loop operation, and uses all sensors except the O2 to determine fuel delivery. Any time an engine is operated in open loop, it runs somewhat rich and makes more exhaust emissions." Your 450Mv indicates a wiring error in the circuit, I'd fix that first then go after the 900Mv ++ rich problem on the other wire side. When looking at raw voltage the O2's should switch between 200 and 800 Mv on a trace or scanner.

 

Im gonna look at the wiring. Any advice on how to check and what to look for?

 

From connector at the O2 end : Pin D pink is +12V ignition thru a splice to under hood fuse block 20A fuse. Pin C black thru splice to chassis ground.. (Pins D and C feed the O2 heater). Pin B Purple is O2 sensor high signal to PCM pin 66 a direct run. Pin A Tan is O2 sensor low signal to PCM pin 26 again a direct run. I believe the PCM is seeing 450 Mv on pin 66 because of an open in the circuit between pins 66 and 26 thru the sensor...Since you swapped wires left to right and the problem stayed in the right side (bank 2) the open s/b in the harness to the right sensor, not an open in the actual sensor (That's my guess) but I am not 100% sure as you can only believe 1/2 of what you read in the manuals. I have never actually worked a problem in this circuit. Assume you checked for burnt/pinched wires back to the PCM..

 

I dont have a speaker on my dmm so I set it on the 200 ohms. I placed one test lead in the purple #66 pin and the other test lead on o2 harness end. Its reading about .4 ohms which should say that the wire is fine (continuity) correct? I did the same thing with the tan #26 pin and same result about .4-.ohms.
I have a hard time believing that the pcm is shot.

 

Well I put a test lead on the ground (black from o2 harness) and other lead to good ground on the car. It reads about the same as others .4ohms.
I did all this with disconnected battery.

 

Im seeing 14.4s with dmm set at 20dcv hooked from power (pink) to ground (black) or to good ground on car.

If im doing all this right then the wiring must be fine. Im ready to start swapping o2s again this is driving me nuts

 

I put in an extra o2 I had in the basement. Cleared codes. Still bank 2 floating around 450mv.
Im starting to think the tuner disabled something or or whatever he did that did this. Is it possible for someone to disable or set parameters,tables (whatever) to make bank to read flatline 450mv?

 

I'm not that familiar with OBD2 software to answer the tuning question, best to ask your tuner or someone knowledgeable on OBD2. The downstream O2's s/b running at 450Mv as that is considered the desired reading after the CAT. A rough test would be to put a high impedance (digital) voltmeter + lead on harness pin 66 at the PCM end and common lead on pin 26 at the PCM end. Then remove the O2 sensor and while it's still plugged up to the harness hold it with pliers or vice grip and heat the tip with a propane torch. With the O2 tip cherry red the voltage reading should read 600-900mv (0.6 -0.9V), Remove the heat and voltage should go to to 0 -100MV (0.0-0.1V) within a second. That proves o2 is alive and basically working. This is a rough test as it does not test O2 switching speed/slope of switching, but it lets you know all the wiring and the sensor is most likely OK. There is an off vehicle test using brake fluid, but it requires the +12V and ground to the heater. Here is the url you can substitute 100mv lean and 900MV rich reading with the meter instead of using an AFR gauge. http://www.youtube.com/watch?v=1mb4VmDd0ao

 

Hey I really aprisiate all the help. You have been more than helpful. Your not gonna belive what was wrong. Look at post #22...
http://www.ls1tech.com/forums/pcm-di...l#post13999071