spark plugs sooty on one side - O2 sensor?

My V6 started throwing error codes once warmed up:
right bank lean
trim differs too much left-right
Engine seems to run okay though.
So I checked out usual stuff. I found all the right side spark plugs are
sooty, and the left side spark plugs have nice brown deposit.
So I suspect the right exhaust oxygen sensor is crying "too lean" and the PCM
is pumping too much fuel into right side. The sensors were probably never
changed (it was a few years old when I bought it).
There exists an error code meaning "no exhaust sensor" but that is not flagged.
Is old exhaust sensor the common cause of this problem?

Also wondering, if there is unburnt fuel, will it wash oil away and cause
accelerated wear?

wrote:
> My V6 started throwing error codes once warmed up:
> right bank lean
> trim differs too much left-right
> Engine seems to run okay though.
> So I checked out usual stuff. I found all the right side spark plugs are
> sooty, and the left side spark plugs have nice brown deposit.
> So I suspect the right exhaust oxygen sensor is crying "too lean" and the PCM
> is pumping too much fuel into right side. The sensors were probably never
> changed (it was a few years old when I bought it).
> There exists an error code meaning "no exhaust sensor" but that is not flagged.
> Is old exhaust sensor the common cause of this problem?
>
> Also wondering, if there is unburnt fuel, will it wash oil away and cause
> accelerated wear?
>
>

Year, Make, Model, Engine?
What are the actual codes that comes up?

Could it be a bad O2?
Yes, Could also be a vacuum leak to the left side, Excessive EGR flow,
Faulty wire harness, Leaking injector, partial converter blockage just
to name a few.

--
Steve W.

Steve W. wrote:
> wrote:
>> My V6 started throwing error codes once warmed up:
>> right bank lean
>> trim differs too much left-right Engine seems to run okay though.
>> So I checked out usual stuff. I found all the right side spark plugs are
>> sooty, and the left side spark plugs have nice brown deposit.
>> So I suspect the right exhaust oxygen sensor is crying "too lean" and
>> the PCM
>> is pumping too much fuel into right side. The sensors were probably never
>> changed (it was a few years old when I bought it).
>> There exists an error code meaning "no exhaust sensor" but that is not
>> flagged.
>> Is old exhaust sensor the common cause of this problem?
>>
>> Also wondering, if there is unburnt fuel, will it wash oil away and cause
>> accelerated wear?
>>
>>
>
> Year, Make, Model, Engine?
> What are the actual codes that comes up?
>
> Could it be a bad O2?
> Yes, Could also be a vacuum leak to the left side, Excessive EGR flow,
> Faulty wire harness, Leaking injector, partial converter blockage just
> to name a few.
>

and to add;

The proper way to diagnose ONE suspected faulty HO2S would be to monitor
them ALL simultaneously with a graphing capable scan tool and force the
engine rich with propane and then lean with a vacuum leak. Observation
and comparison tells the tail.

I suppose the backyard way would be to switch the left and right ones
and see if the other side's plugs turn black...have fun
GW