exhaust sensor readings bad [V6]

[jeepster]

I replaced the exhaust oxygen sensors recently, and it runs worse. Also the exhaust is black with soot. So I put a Vident scan tool on it. Error codes are 76 and 78, meaning the trim differs too much left versus right. Then look at exhaust sensor readout. One is zero volts and the other is 1.05 volts. 1.05 means much richer than stoichiometric ratio. So presumably the PCM is pumping out more fuel trying to correct the zero volts, and eventually gives up setting error codes. But the other side with high voltage. it should be reducing fuel, and the voltage should come down. Any ideas what could be wrong? First I suspected the zero volt side was unplugged, but had a look, connector is firmly together.

 

[Drawnnite]

Dodgy earth?
I remember something from many years ago about the potential bad earths near the pcm/bcm whatever it is in the kick panel of the footwear.
Something about redoing those earths comes to mind. Been a long time but info is on this forum somewhere.

Also is it the correct type of o2 sensor?
Again not 100% sure but a later model uses a different o2 sensor? Maybe I am thinking a 2wire vs 4wire one.

Otherwise simple stuff like plugs, leads, even clean the maf so it knows the right Air flow going in. Many things could be reading wrongly causing it to compensate.

 

[losh1971]

Which brand O2s did you buy?

 

[jeepster]

Which brand O2s did you buy?

They are Bosch, 4-wire model.

 

[losh1971]

They are Bosch, 4-wire model.

Did they come with the plug, or did you have to splice them?

 

[jeepster]

Did they come with the plug, or did you have to splice them?

No came with the plug. I already did my mum's VS with the same sensors a few years ago.

 

[ephect]

Swap the sensors over, left to right, right to left, to see if the issue follows the sensor or its the wiring.

Clear codes and go for a strap, post back

 

[jeepster]

Clear codes and go for a strap, post back

Problem seems to be Vident scan tool. I put it on another V6 V6. This one low-mileage, runs very well, no error codes. It shows left oxygen sensor 0 volts and right sensor 110 mV all the time, hot or cold. Mine also shows this if you just turn ignition on with cold engine. Still something wrong with mine. Looking at it with TunerPro, 3 of the 4 trims are shown in red on dashboard, presumably bad. Unfortunately laptop has a pitiful low-res screen and I cannot read the data dump.

 

[Lex]

laptop has a pitiful low-res screen and I cannot read the data dump.

Are you able to use windows magnifier on it (assuming its a windows laptop)?
It may help to read it?

 

[jeepster]

Are you able to use windows magnifier on it (assuming its a windows laptop)?
It may help to read it?

I figured out how to change the dashboard. Replaced the short-term trim with O2 sensor millvolts. It is completely erratic, jumping by hundreds from one scan to the next. Left would have lower average than right. I would say there is a sh*tload of noise in the sensor wiring.