Re: check engine light on in 97 wrangler YJ with error code reading 72
 

"bllsht" <nospam@dot.net> wrote in message
news:tjn0r2thspsahs0fe62phd596o42jcrkag@4ax.com...
> On Fri, 19 Jan 2007 05:11:08 GMT, "Jeff Strickland"
> <crwlr@verizon.net> wrote:
>
>>
>>"bllsht" <nospam@dot.net> wrote in message
>>news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com. ..
>>>
>>>
>>>
>>> You're both leaping to conclusions without even having a clue as to
>>> how the PCM determines the cat converter's efficiency.
>>>
>>
>>I'm not leaping to anything. If you would like to tell us how ti works, go
>>ahead. but, my guess is that it will boil down nicely to, "what comes out
>>of
>>the CAT is not correct relative to what went in."
>>
>>If what goes into the CAT is not correct, then there is a code that
>>specifies this condition. What comes out might not be correct, but if what
>>wen it was not correct first, that is the code to fix. If there is no code
>>addressing the condition of what goes into the CAT, but there is one that
>>addresses what comes out, I'll put my money on the sensor as the first and
>>foremost most likely suspect.
>>
>>
>>
>
> And you would be wrong again.

So, explain where I am wrong.

Re: check engine light on in 97 wrangler YJ with error code reading 72
 

On Fri, 19 Jan 2007 16:39:41 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"bllsht" <nospam@dot.net> wrote in message
>news:tjn0r2thspsahs0fe62phd596o42jcrkag@4ax.com.. .
>> On Fri, 19 Jan 2007 05:11:08 GMT, "Jeff Strickland"
>> <crwlr@verizon.net> wrote:
>>
>>>
>>>"bllsht" <nospam@dot.net> wrote in message
>>>news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com ...
>>>>
>>>>
>>>>
>>>> You're both leaping to conclusions without even having a clue as to
>>>> how the PCM determines the cat converter's efficiency.
>>>>
>>>
>>>I'm not leaping to anything. If you would like to tell us how ti works, go
>>>ahead. but, my guess is that it will boil down nicely to, "what comes out
>>>of
>>>the CAT is not correct relative to what went in."
>>>
>>>If what goes into the CAT is not correct, then there is a code that
>>>specifies this condition. What comes out might not be correct, but if what
>>>wen it was not correct first, that is the code to fix. If there is no code
>>>addressing the condition of what goes into the CAT, but there is one that
>>>addresses what comes out, I'll put my money on the sensor as the first and
>>>foremost most likely suspect.
>>>
>>>
>>>
>>
>> And you would be wrong again.
>
>So, explain where I am wrong.
>
>
>

You mean other than not having a clue as to how the system works? OK
then, here you go.

First, testing a cat's efficiency means testing it's ability to store
oxygen. In a high O2 environment(lean) it stores oxygen. In a low O2
environment(rich) it releases oxygen.

The PCM constantly drives the system between rich & lean. Ahead of the
cat, the upstream O2 is constantly switching between high oxygen and
low oxygen. After the cat, the downstream O2 sees a more even oxygen
level because of the cat, so it won't switch as much.

The PCM determines the cat's ability to store and release oxygen by
the ratio of switching between the upstream and downstream O2 sensors.
As the cat ages and becomes less efficient, the downstream O2 sensor's
switch rate starts to approach that of the upstream O2. When it gets
close enough a cat efficiency fault is set.

As O2 sensors age, their ability to switch degrades. They slow down or
stop switching altogether.

Now tell me, if a fast switching downstream oxygen sensor means the
cat is degrading, how can a failed/slow downstream sensor cause a cat
efficiency fault? It can't. The PCM thinks the cat is working or it
determines the sensor has failed.

Re: check engine light on in 97 wrangler YJ with error code reading 72
 

On Fri, 19 Jan 2007 16:39:41 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"bllsht" <nospam@dot.net> wrote in message
>news:tjn0r2thspsahs0fe62phd596o42jcrkag@4ax.com.. .
>> On Fri, 19 Jan 2007 05:11:08 GMT, "Jeff Strickland"
>> <crwlr@verizon.net> wrote:
>>
>>>
>>>"bllsht" <nospam@dot.net> wrote in message
>>>news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com ...
>>>>
>>>>
>>>>
>>>> You're both leaping to conclusions without even having a clue as to
>>>> how the PCM determines the cat converter's efficiency.
>>>>
>>>
>>>I'm not leaping to anything. If you would like to tell us how ti works, go
>>>ahead. but, my guess is that it will boil down nicely to, "what comes out
>>>of
>>>the CAT is not correct relative to what went in."
>>>
>>>If what goes into the CAT is not correct, then there is a code that
>>>specifies this condition. What comes out might not be correct, but if what
>>>wen it was not correct first, that is the code to fix. If there is no code
>>>addressing the condition of what goes into the CAT, but there is one that
>>>addresses what comes out, I'll put my money on the sensor as the first and
>>>foremost most likely suspect.
>>>
>>>
>>>
>>
>> And you would be wrong again.
>
>So, explain where I am wrong.
>
>
>

You mean other than not having a clue as to how the system works? OK
then, here you go.

First, testing a cat's efficiency means testing it's ability to store
oxygen. In a high O2 environment(lean) it stores oxygen. In a low O2
environment(rich) it releases oxygen.

The PCM constantly drives the system between rich & lean. Ahead of the
cat, the upstream O2 is constantly switching between high oxygen and
low oxygen. After the cat, the downstream O2 sees a more even oxygen
level because of the cat, so it won't switch as much.

The PCM determines the cat's ability to store and release oxygen by
the ratio of switching between the upstream and downstream O2 sensors.
As the cat ages and becomes less efficient, the downstream O2 sensor's
switch rate starts to approach that of the upstream O2. When it gets
close enough a cat efficiency fault is set.

As O2 sensors age, their ability to switch degrades. They slow down or
stop switching altogether.

Now tell me, if a fast switching downstream oxygen sensor means the
cat is degrading, how can a failed/slow downstream sensor cause a cat
efficiency fault? It can't. The PCM thinks the cat is working or it
determines the sensor has failed.

Re: check engine light on in 97 wrangler YJ with error code reading 72
 

On Fri, 19 Jan 2007 16:39:41 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"bllsht" <nospam@dot.net> wrote in message
>news:tjn0r2thspsahs0fe62phd596o42jcrkag@4ax.com.. .
>> On Fri, 19 Jan 2007 05:11:08 GMT, "Jeff Strickland"
>> <crwlr@verizon.net> wrote:
>>
>>>
>>>"bllsht" <nospam@dot.net> wrote in message
>>>news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com ...
>>>>
>>>>
>>>>
>>>> You're both leaping to conclusions without even having a clue as to
>>>> how the PCM determines the cat converter's efficiency.
>>>>
>>>
>>>I'm not leaping to anything. If you would like to tell us how ti works, go
>>>ahead. but, my guess is that it will boil down nicely to, "what comes out
>>>of
>>>the CAT is not correct relative to what went in."
>>>
>>>If what goes into the CAT is not correct, then there is a code that
>>>specifies this condition. What comes out might not be correct, but if what
>>>wen it was not correct first, that is the code to fix. If there is no code
>>>addressing the condition of what goes into the CAT, but there is one that
>>>addresses what comes out, I'll put my money on the sensor as the first and
>>>foremost most likely suspect.
>>>
>>>
>>>
>>
>> And you would be wrong again.
>
>So, explain where I am wrong.
>
>
>

You mean other than not having a clue as to how the system works? OK
then, here you go.

First, testing a cat's efficiency means testing it's ability to store
oxygen. In a high O2 environment(lean) it stores oxygen. In a low O2
environment(rich) it releases oxygen.

The PCM constantly drives the system between rich & lean. Ahead of the
cat, the upstream O2 is constantly switching between high oxygen and
low oxygen. After the cat, the downstream O2 sees a more even oxygen
level because of the cat, so it won't switch as much.

The PCM determines the cat's ability to store and release oxygen by
the ratio of switching between the upstream and downstream O2 sensors.
As the cat ages and becomes less efficient, the downstream O2 sensor's
switch rate starts to approach that of the upstream O2. When it gets
close enough a cat efficiency fault is set.

As O2 sensors age, their ability to switch degrades. They slow down or
stop switching altogether.

Now tell me, if a fast switching downstream oxygen sensor means the
cat is degrading, how can a failed/slow downstream sensor cause a cat
efficiency fault? It can't. The PCM thinks the cat is working or it
determines the sensor has failed.

Re: check engine light on in 97 wrangler YJ with error code reading 72
 

On Fri, 19 Jan 2007 16:39:41 GMT, "Jeff Strickland"
<crwlr@verizon.net> wrote:

>
>"bllsht" <nospam@dot.net> wrote in message
>news:tjn0r2thspsahs0fe62phd596o42jcrkag@4ax.com.. .
>> On Fri, 19 Jan 2007 05:11:08 GMT, "Jeff Strickland"
>> <crwlr@verizon.net> wrote:
>>
>>>
>>>"bllsht" <nospam@dot.net> wrote in message
>>>news:51j0r2lejqa7apj35s5jhrni154b3c4vq0@4ax.com ...
>>>>
>>>>
>>>>
>>>> You're both leaping to conclusions without even having a clue as to
>>>> how the PCM determines the cat converter's efficiency.
>>>>
>>>
>>>I'm not leaping to anything. If you would like to tell us how ti works, go
>>>ahead. but, my guess is that it will boil down nicely to, "what comes out
>>>of
>>>the CAT is not correct relative to what went in."
>>>
>>>If what goes into the CAT is not correct, then there is a code that
>>>specifies this condition. What comes out might not be correct, but if what
>>>wen it was not correct first, that is the code to fix. If there is no code
>>>addressing the condition of what goes into the CAT, but there is one that
>>>addresses what comes out, I'll put my money on the sensor as the first and
>>>foremost most likely suspect.
>>>
>>>
>>>
>>
>> And you would be wrong again.
>
>So, explain where I am wrong.
>
>
>

You mean other than not having a clue as to how the system works? OK
then, here you go.

First, testing a cat's efficiency means testing it's ability to store
oxygen. In a high O2 environment(lean) it stores oxygen. In a low O2
environment(rich) it releases oxygen.

The PCM constantly drives the system between rich & lean. Ahead of the
cat, the upstream O2 is constantly switching between high oxygen and
low oxygen. After the cat, the downstream O2 sees a more even oxygen
level because of the cat, so it won't switch as much.

The PCM determines the cat's ability to store and release oxygen by
the ratio of switching between the upstream and downstream O2 sensors.
As the cat ages and becomes less efficient, the downstream O2 sensor's
switch rate starts to approach that of the upstream O2. When it gets
close enough a cat efficiency fault is set.

As O2 sensors age, their ability to switch degrades. They slow down or
stop switching altogether.

Now tell me, if a fast switching downstream oxygen sensor means the
cat is degrading, how can a failed/slow downstream sensor cause a cat
efficiency fault? It can't. The PCM thinks the cat is working or it
determines the sensor has failed.