"bllsht" <nospam@invaliddot.net> wrote in message
news:b1pdm1l9sifn7nlbjhcj0ae0e7rbumt310@4ax.com...
> In message <7JadnXn_ufJbDfveRVn-jg@ez2.net>, "Jeff Strickland" wrote:
>
>>I'd replace the O2 Sensor. It should be the one closest to the motor. If
>>you
>>have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank
>>2, the I6 only has Bank 1.
>
> A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl
> will.
>


Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
are both before the CAT, and if there is one after the CAT, then it is not
Bank 1 OR Bank 2.



>>
>>If there was an O2 Sensor after the CAT, then the code would be that the
>>CAT
>>isn't working right. I forget the specific verbiage, but the CAT has no
>>parts that can fail, so a failed CAT is probably caused by a failed
>>sensor.
>>Having said that, a CAT _can_ fail, but you usually know because the main
>>failure mode is that it gets clogged and this affects performance.
>
> You make this up as you go? Cat converters can and quite often do fail
> without
> plugging or rattling. If that wasn't the case, there would be no need to
> monitor them for efficiency. If you get a fault for a failed cat, chances
> are
> the cat is hosed. If there's a problem with the downstream sensor, you'll
> get a
> downstream sensor fault. Not a cat failure fault.
>

Yes, you're right. CATs do fail.

But they have no moving parts, and the most likely failure is the after-CAT
sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
won't always know that it has failed, it'll _think_ that the CAT is gone
first.

 

"bllsht" <nospam@invaliddot.net> wrote in message
news:b1pdm1l9sifn7nlbjhcj0ae0e7rbumt310@4ax.com...
> In message <7JadnXn_ufJbDfveRVn-jg@ez2.net>, "Jeff Strickland" wrote:
>
>>I'd replace the O2 Sensor. It should be the one closest to the motor. If
>>you
>>have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank
>>2, the I6 only has Bank 1.
>
> A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl
> will.
>


Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
are both before the CAT, and if there is one after the CAT, then it is not
Bank 1 OR Bank 2.



>>
>>If there was an O2 Sensor after the CAT, then the code would be that the
>>CAT
>>isn't working right. I forget the specific verbiage, but the CAT has no
>>parts that can fail, so a failed CAT is probably caused by a failed
>>sensor.
>>Having said that, a CAT _can_ fail, but you usually know because the main
>>failure mode is that it gets clogged and this affects performance.
>
> You make this up as you go? Cat converters can and quite often do fail
> without
> plugging or rattling. If that wasn't the case, there would be no need to
> monitor them for efficiency. If you get a fault for a failed cat, chances
> are
> the cat is hosed. If there's a problem with the downstream sensor, you'll
> get a
> downstream sensor fault. Not a cat failure fault.
>

Yes, you're right. CATs do fail.

But they have no moving parts, and the most likely failure is the after-CAT
sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
won't always know that it has failed, it'll _think_ that the CAT is gone
first.

 

"bllsht" <nospam@invaliddot.net> wrote in message
news:b1pdm1l9sifn7nlbjhcj0ae0e7rbumt310@4ax.com...
> In message <7JadnXn_ufJbDfveRVn-jg@ez2.net>, "Jeff Strickland" wrote:
>
>>I'd replace the O2 Sensor. It should be the one closest to the motor. If
>>you
>>have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank
>>2, the I6 only has Bank 1.
>
> A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl
> will.
>


Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
are both before the CAT, and if there is one after the CAT, then it is not
Bank 1 OR Bank 2.



>>
>>If there was an O2 Sensor after the CAT, then the code would be that the
>>CAT
>>isn't working right. I forget the specific verbiage, but the CAT has no
>>parts that can fail, so a failed CAT is probably caused by a failed
>>sensor.
>>Having said that, a CAT _can_ fail, but you usually know because the main
>>failure mode is that it gets clogged and this affects performance.
>
> You make this up as you go? Cat converters can and quite often do fail
> without
> plugging or rattling. If that wasn't the case, there would be no need to
> monitor them for efficiency. If you get a fault for a failed cat, chances
> are
> the cat is hosed. If there's a problem with the downstream sensor, you'll
> get a
> downstream sensor fault. Not a cat failure fault.
>

Yes, you're right. CATs do fail.

But they have no moving parts, and the most likely failure is the after-CAT
sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
won't always know that it has failed, it'll _think_ that the CAT is gone
first.

 

:-)

Jeff Strickland wrote:
>
> Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
> are both before the CAT, and if there is one after the CAT, then it is not
> Bank 1 OR Bank 2.
>
> Yes, you're right. CATs do fail.
>
> But they have no moving parts, and the most likely failure is the after-CAT
> sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
> won't always know that it has failed, it'll _think_ that the CAT is gone
> first.

 

:-)

Jeff Strickland wrote:
>
> Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
> are both before the CAT, and if there is one after the CAT, then it is not
> Bank 1 OR Bank 2.
>
> Yes, you're right. CATs do fail.
>
> But they have no moving parts, and the most likely failure is the after-CAT
> sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
> won't always know that it has failed, it'll _think_ that the CAT is gone
> first.

 

:-)

Jeff Strickland wrote:
>
> Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
> are both before the CAT, and if there is one after the CAT, then it is not
> Bank 1 OR Bank 2.
>
> Yes, you're right. CATs do fail.
>
> But they have no moving parts, and the most likely failure is the after-CAT
> sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
> won't always know that it has failed, it'll _think_ that the CAT is gone
> first.

 

In message <SqmdnQ8cjYTs-_TeRVn-oQ@ez2.net>, "Jeff Strickland" wrote:

>
>"bllsht" <nospam@invaliddot.net> wrote in message
>news:b1pdm1l9sifn7nlbjhcj0ae0e7rbumt310@4ax.com.. .
>> In message <7JadnXn_ufJbDfveRVn-jg@ez2.net>, "Jeff Strickland" wrote:
>>
>>>I'd replace the O2 Sensor. It should be the one closest to the motor. If
>>>you
>>>have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank
>>>2, the I6 only has Bank 1.
>>
>> A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl
>> will.
>>
>
>
>Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
>are both before the CAT, and if there is one after the CAT, then it is not
>Bank 1 OR Bank 2.

By default, if there's one O2 before the cat, it's the bank 1 upstream.
Likewise, the downstream sensor will be bank 1 downstream. That's the way they
are referred to by scan tools.

>
>
>
>>>
>>>If there was an O2 Sensor after the CAT, then the code would be that the
>>>CAT
>>>isn't working right. I forget the specific verbiage, but the CAT has no
>>>parts that can fail, so a failed CAT is probably caused by a failed
>>>sensor.
>>>Having said that, a CAT _can_ fail, but you usually know because the main
>>>failure mode is that it gets clogged and this affects performance.
>>
>> You make this up as you go? Cat converters can and quite often do fail
>> without
>> plugging or rattling. If that wasn't the case, there would be no need to
>> monitor them for efficiency. If you get a fault for a failed cat, chances
>> are
>> the cat is hosed. If there's a problem with the downstream sensor, you'll
>> get a
>> downstream sensor fault. Not a cat failure fault.
>>
>
>Yes, you're right. CATs do fail.
>
>But they have no moving parts, and the most likely failure is the after-CAT
>sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
>won't always know that it has failed, it'll _think_ that the CAT is gone
>first.
>


If you had a clue as to how the system operates, you'd know the sensor doesn't
_think_ anything. It just changes voltage as O2 content changes. Alone, it
can't cause a cat efficiency failure. The PCM determines whether the cat is
operating properly or not, by looking at upstream vs downstream switch rates.

A brand new, perfectly operating downstream O2 sensor would be more likely to
trigger a cat fault than an old worn out, slow switching sensor.

An old worn out inoperative downstream O2 sensor will trigger a downstream O2
sensor fault. NOT a cat fault.

 

In message <SqmdnQ8cjYTs-_TeRVn-oQ@ez2.net>, "Jeff Strickland" wrote:

>
>"bllsht" <nospam@invaliddot.net> wrote in message
>news:b1pdm1l9sifn7nlbjhcj0ae0e7rbumt310@4ax.com.. .
>> In message <7JadnXn_ufJbDfveRVn-jg@ez2.net>, "Jeff Strickland" wrote:
>>
>>>I'd replace the O2 Sensor. It should be the one closest to the motor. If
>>>you
>>>have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank
>>>2, the I6 only has Bank 1.
>>
>> A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl
>> will.
>>
>
>
>Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
>are both before the CAT, and if there is one after the CAT, then it is not
>Bank 1 OR Bank 2.

By default, if there's one O2 before the cat, it's the bank 1 upstream.
Likewise, the downstream sensor will be bank 1 downstream. That's the way they
are referred to by scan tools.

>
>
>
>>>
>>>If there was an O2 Sensor after the CAT, then the code would be that the
>>>CAT
>>>isn't working right. I forget the specific verbiage, but the CAT has no
>>>parts that can fail, so a failed CAT is probably caused by a failed
>>>sensor.
>>>Having said that, a CAT _can_ fail, but you usually know because the main
>>>failure mode is that it gets clogged and this affects performance.
>>
>> You make this up as you go? Cat converters can and quite often do fail
>> without
>> plugging or rattling. If that wasn't the case, there would be no need to
>> monitor them for efficiency. If you get a fault for a failed cat, chances
>> are
>> the cat is hosed. If there's a problem with the downstream sensor, you'll
>> get a
>> downstream sensor fault. Not a cat failure fault.
>>
>
>Yes, you're right. CATs do fail.
>
>But they have no moving parts, and the most likely failure is the after-CAT
>sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
>won't always know that it has failed, it'll _think_ that the CAT is gone
>first.
>


If you had a clue as to how the system operates, you'd know the sensor doesn't
_think_ anything. It just changes voltage as O2 content changes. Alone, it
can't cause a cat efficiency failure. The PCM determines whether the cat is
operating properly or not, by looking at upstream vs downstream switch rates.

A brand new, perfectly operating downstream O2 sensor would be more likely to
trigger a cat fault than an old worn out, slow switching sensor.

An old worn out inoperative downstream O2 sensor will trigger a downstream O2
sensor fault. NOT a cat fault.

 

In message <SqmdnQ8cjYTs-_TeRVn-oQ@ez2.net>, "Jeff Strickland" wrote:

>
>"bllsht" <nospam@invaliddot.net> wrote in message
>news:b1pdm1l9sifn7nlbjhcj0ae0e7rbumt310@4ax.com.. .
>> In message <7JadnXn_ufJbDfveRVn-jg@ez2.net>, "Jeff Strickland" wrote:
>>
>>>I'd replace the O2 Sensor. It should be the one closest to the motor. If
>>>you
>>>have an I6, it will be on the manifold. A V8 will have a Bank 1 and a Bank
>>>2, the I6 only has Bank 1.
>>
>> A 97 V8 will have 1 upstream and 1 downstream sensor. Just like a 6 cyl
>> will.
>>
>
>
>Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
>are both before the CAT, and if there is one after the CAT, then it is not
>Bank 1 OR Bank 2.

By default, if there's one O2 before the cat, it's the bank 1 upstream.
Likewise, the downstream sensor will be bank 1 downstream. That's the way they
are referred to by scan tools.

>
>
>
>>>
>>>If there was an O2 Sensor after the CAT, then the code would be that the
>>>CAT
>>>isn't working right. I forget the specific verbiage, but the CAT has no
>>>parts that can fail, so a failed CAT is probably caused by a failed
>>>sensor.
>>>Having said that, a CAT _can_ fail, but you usually know because the main
>>>failure mode is that it gets clogged and this affects performance.
>>
>> You make this up as you go? Cat converters can and quite often do fail
>> without
>> plugging or rattling. If that wasn't the case, there would be no need to
>> monitor them for efficiency. If you get a fault for a failed cat, chances
>> are
>> the cat is hosed. If there's a problem with the downstream sensor, you'll
>> get a
>> downstream sensor fault. Not a cat failure fault.
>>
>
>Yes, you're right. CATs do fail.
>
>But they have no moving parts, and the most likely failure is the after-CAT
>sensor. And the sensor is cheaper than the CAT by a wide margin. The Sensor
>won't always know that it has failed, it'll _think_ that the CAT is gone
>first.
>


If you had a clue as to how the system operates, you'd know the sensor doesn't
_think_ anything. It just changes voltage as O2 content changes. Alone, it
can't cause a cat efficiency failure. The PCM determines whether the cat is
operating properly or not, by looking at upstream vs downstream switch rates.

A brand new, perfectly operating downstream O2 sensor would be more likely to
trigger a cat fault than an old worn out, slow switching sensor.

An old worn out inoperative downstream O2 sensor will trigger a downstream O2
sensor fault. NOT a cat fault.

 

Jeff Strickland wrote:>
>
> Yes, but Bank 1 is one side of the motor, Bank 2 is the other side. These
> are both before the CAT, and if there is one after the CAT, then it is not
> Bank 1 OR Bank 2.
>

Actually, the way GM numbers them, any of the sensors with exhaust from
the #1 cyl flowing past it is considered Bank 1. Thus, the one after
the cat is called Bank 1 Sensor 2.

However, if it's a dual cat setup...then you have 4 sensors, bank 1
sensors 1&2, and bank 2 sensors 1&2.

The parts guys just love trying to figure it out, because their book
names them altogether differently(something like positions 1, 2 and 3).


--
Old Crow
'82 FLTC-P "Pearl"
'95 Wrangler YJ
TOMKAT, SENS, BS#133, MAMBM, SLOB#13, DH#2