Another oxygen sensor question

[baroofy]

I have a vs series 2 commodore, error code 76 air/fuel ratio.new leads,plugs and fuel injectors fitted. still same code. (right bank richer than left)
When checking O2 sensors these were the results i got at the ecu terminal 15 & 13.

Left side ignition on 0 volts (with the sensor unpluged 0.35 volts)
engine idle 0.75 volts
engine 1800 rpm fluctuating 0.1 to 1 volt

right side ignition on 8.5 volts (with the sensor unpluged 0.35 volts)
engine idle 0.85 volts
engine 1800 rpm 0.85 volts steady

Would this be a earthing problem or would i need new 02 sensors or both.

Thanks for any advice Baroofy

 

[IBLOWN]

Need to check resistance at the ECU from each oxygen sensor.

Its a common problem on the VS having a bad earth to 1 of the oxygen sensors.

Find the bad earth and bridge it to the good earth terminal for the other oxygen sensor at the ECU.

 

[aceventura]

It is an earthing problem, whether you need to replace the sensors or not is difficult to say. Wait till you fix the earthing problem and then have another look at the cross counts and voltage swing of the sensors.

To fix the problem, you can do three things (in increasing order of difficulty):
1) Cut the heater power wire (numerous threads on this)
2) Fix the earth in the engine bay (a thread by immortality somewhere)
3) Fix the earth at the ECU

I fixed mine by re-routing the heater circuit earth wire on the sensor directly to the engine block and it works fine.

 

[baroofy]

Thanks for the quick replies. I will fix the earth problem first.

 

[Brett_jjj]

Not all of the VS's have this 02 sensor earthing problem.Also,Ive found that when certain versions of the VS memcals are used in certain VS models,it can stuff up the oxygen sesor readings,or even make them pretty much non existant for some reason,so it actually gives very similar symptoms as the earthing problem,so if you have changed over memcals or ECU's for whatever reason,(fitted a tuned memcal or whatever),then this can also be the cause of the bad 02 sensor readings.(depending on what memcal version was used to do the tune on)..Its also worth making sure that the 02 sensor earth points on the engine are clean and tight.These are the two black earth wires which are located at the front of the engine near the serpentine belt tensioner area...Also the oxygen sensors themselves wear out over time, just like any other part does,so they will need replacing from time to time.They should be replaced every 100,000 km.
I should also mention that I found that when the wrong memcal is used and its causing the bad 02 sensor readings,doing the 02 earth fix, wont fix the 02 sensor readings in these cases...

 

[baroofy]

The problem was an earthing problem. when i re eathered both O2 sensors and the right hand O2 heater wire the problem went away. the exhaust is a lot cleaner, fuel consumption is a lot better and the error code has gone.
Thanks for the help and advice Baroofy.