OBD-II: testing cat for NOx adsorption

On 11/06/2010 08:43 AM, aarcuda69062 wrote:
> In article<eqGdnSzSFJG66UjRnZ2dnUVZ_gGdnZ2d@speakeasy .net>,
> jim > wrote:
>
>> On 11/06/2010 07:58 AM, aarcuda69062 wrote:
>>> In >,
>>> > wrote:
>>>
>>>> > wrote in
>>>> news:nonelson-A83C49.22013905112010@reserved-multicast-range-NOT-delegate
>>>> d.example.com:
>>>>
>>>>> In >,
>>>>> > wrote:
>>>>>
>>>>>> I know the ECM tests the cat's oxidation-side for O2 storage by
>>>>>> 1) commanding rich for 5 seconds to drain the cat of O2, then
>>>>>> 2) commanding lean for 5 seconds to load the cat with O2 while
>>>>>> 3) counting the time that passes before the secondary HO2S flips.
>>>>>
>>>>> That hasn't been my observation, but maybe possible that a few
>>>>> manufacturers that I'm not familiar with have adopted that strategy...
>>>>
>>>>
>>>>
>>>> A training document I have says that's how Honda does it.
>>>>
>>>> My concern has specifically do with an OBD-II Honda, but I had the
>>>> (evidently erroneous) idea that the general processes were the same across
>>>> automakers.
>>>
>>> I won't dispute that the injector pulse width alternates between
>>> slightly lean and slightly rich, the 5 second interval though does not
>>> jive with conventional wisdom or what can be observed when one views O2
>>> sensor activity on a lab scope and injector on time on a lab scope via a
>>> low amps probe.
>>
>> translation: it's typically faster than 5 seconds.
>
> But Teggers' training document says 5 seconds. Are you suggesting that
> there may be some bad information being offered Jim?

yup. and it wouldn't be the first time in the automotive world. but it
might be the maximum interval also. i don't know what honda do, but if
they cycle slower as catalysts degrade and become less responsive, that
might explain. just guessing.


>
>>
>>>
>>>>
>>>>>
>>>>>> But how does it test for proper NO (NOx) handling?
>>>>>
>>>>> The same way it tests for proper HC and CO handling.
>>>>
>>>>
>>>>
>>>> Do you mind giving me a quick overview of what your observations are
>>>> regarding this?
>>>
>>> The best opportunity is right after you replace a catalytic converter
>>> using OEM parts. First step is making sure the PCM has proper fuel
>>> control including proper airflow measurement. Test drive the vehicle
>>> under varied operating conditions, typically the upstream O2s will be
>>> cycling during idle and cruise. The down stream O2s will be outputing
>>> near 900mv and you may see the occasional swing to low voltage as the
>>> cat burps off O2 as the cat-con becomes saturated.
>>>
>>>> I'm particularly interested in how the ECM uses the secondary O2 sensor to
>>>> tell the difference between HC/CO and NO handling.
>>>
>>> It wouldn't necessarily see a difference such that it would specifically
>>> identify NOx exceeding the FTP threshold, NOx, CO and HC treatment are
>>> all part of the same catalytic process.
>>
>> no, they're separate processes. there are typically two separate
>> matricies on a modern catalytic converter - platinum/palladium on the
>> [front] carbon end, platinum/rhodium on the [rear] nitrogen end.
>>
>> again: http://www.ridelust.com/wp-content/u...cconverter.jpg
>
> Again: 1980s watered down wisdom not to mention backwards.

show me something [authoritative] that says different then! i've told
you what i understand the chemistry to be.


>
>>
>>> As that process degrades the
>>> downstream O2 sensor output begins to mimic the upstream O2 sensor
>>> output.
>>>
>>> This may all change in the future if and when the OEMs begin using
>>> dedicated NOx sensors in the exhaust stream. Prepare for some
>>> astronomical sensor prices when that happens...
>>
>> let us know when anyone starts using nitrogen sensors...
>
> I will.

the point being that they're not in use yet.


--
nomina rutrum rutrum

In article > ,
jim beam > wrote:

> On 11/06/2010 08:30 AM, aarcuda69062 wrote:
> > In article<ZIednWtSc6Jc9UjRnZ2dnUVZ_vkAAAAA@speakeasy .net>,
> > jim > wrote:
> >
> >> On 11/06/2010 06:01 AM, Tegger wrote:
> >>> > wrote in
> >>> news:nonelson-A83C49.22013905112010@reserved-multicast-range-NOT-delegate
> >>> d.example.com:
> >>>
> >>>> In >,
> >>>> > wrote:
> >>>>
> >>>>> I know the ECM tests the cat's oxidation-side for O2 storage by
> >>>>> 1) commanding rich for 5 seconds to drain the cat of O2, then
> >>>>> 2) commanding lean for 5 seconds to load the cat with O2 while
> >>>>> 3) counting the time that passes before the secondary HO2S flips.
> >>>>
> >>>> That hasn't been my observation, but maybe possible that a few
> >>>> manufacturers that I'm not familiar with have adopted that strategy...
> >>>
> >>>
> >>>
> >>> A training document I have says that's how Honda does it.
> >>>
> >>> My concern has specifically do with an OBD-II Honda, but I had the
> >>> (evidently erroneous) idea that the general processes were the same across
> >>> automakers.
> >>>
> >>>
> >>>>
> >>>>> But how does it test for proper NO (NOx) handling?
> >>>>
> >>>> The same way it tests for proper HC and CO handling.
> >>>
> >>>
> >>>
> >>> Do you mind giving me a quick overview of what your observations are
> >>> regarding this?
> >>>
> >>> I'm particularly interested in how the ECM uses the secondary O2 sensor to
> >>> tell the difference between HC/CO and NO handling.
> >>
> >> it doesn't and it can't - it's an oxygen sensor. however, the efficacy
> >> of the cat's carbon and nitrogen catalysis go hand in hand, so if one
> >> end is degrading, the other is presumed to be degrading too.
> >>
> >>
> >>>
> >>>
> >>>
> >>>
> >>>>
> >>>>> The reduction side
> >>>>
> >>>> There is no reduction "side." The oxidation and reduction processes
> >>>> occur at the same place, same time on the noble metals within the
> >>>> cat-con.
> >>>
> >>>
> >>>
> >>> Thank you. I didn't know that.
> >>
> >> hopefully because it's not correct. there are two different honeycombs
> >> in the modern cat. ^^^^^^
> >
> > That may have been the design back in the 80s, it isn't how it's done
> > now. There may be two ceramic bricks but they contain the same metals
> > and function the same way.
>
> untrue.
>
> http://en.wikipedia.org/wiki/Rhodium#Catalyst
> http://en.wikipedia.org/wiki/Palladium#Catalysis

Nothing there to disprove anything I've said so far.
The picture shows two ceramic bricks, it doesn't however define that
there roles are separate or different.

> catalysis occurs at different temperatures too - that's why people are
> taught too use an i.r. thermometer on a cat to see if it's working
> correctly.

And that test has long ago been refuted. It is a worthless waste of
time.

> i'm not giving you a hard time - it's just that a lot of car tech
> teaching and information on this subject is "black box" - you don't
> /need/ to know what's really going on inside, and most people don't know
> anyway.

Precisely my point. (thank you veddy much).
Much of what is thought to be true comes from space limited articles in
Popular Science type magazines. Things like using an IR temperature gun
to diagnose whether a catalytic converter is working for instance...

>
> >
> >> first one [engine end] deals with carbon. the
> >> second, [tailpipe end] deals with nitrogen.
> >
> > Not only is that statement backwards, it makes no sense.
> > If the "tailpipe end" of the cat is the NOx reduction part, it wouldn't
> > be able to contribute oxygen molecules to assist the oxidation of HC and
> > CO.
>
> see above. you need oxyhen to reduce CO to CO???.

Are you asking??? Where in any of this did I state that CO is reduced?
Do you even understand the difference between reduction and oxidation?

You need oxygen to OXIDIZE HC and CO, if that oxygen can be obtained via
the reduction of NOx to N2 and O2 it would certainly make sense to do
that process upstream of the oxidation rather than downstream as you
assert.

> NOx you can just split
> - per the wiki link.

Yes, that is the reduction.

>
> >
> > But let's go back to the 80s when they did use an air tap into the
> > cat-con, that tap was typically placed in the center of the cat-con,
> > does it make sense that a NOx reduction could be accomplished using the
> > addition of Nitrogen as part of the process?
>
> good point, but what i understand is that in modern fuel injection
> systems, there is sufficient oxygen in the exhaust stream to oxidize the
> carbon/hydrocarbon content,

There is, it is attached to the nitrogen (NOx).

Rather than state "modern fuel injection systems" substitute 'modern
catalytic converters.'

If I showed you a O2 sensor signal from a 1982 Chevrolet Caprice side by
side with an O2 sensor signal from a 2007 Chevrolet Tahoe, you'd be hard
pressed to distinguish one from the other. The feed gasses are
essentially the same, the O2 content is the same, it's the catalytic
converters that have gotten much more efficient. 95% efficiency could
only be dreamed of 20 years ago.

That increased efficiency is due to the things I stated earlier, things
you said I was wrong about.

> so that's done first to raise temperatures
> that allow the nitrogen conversion to happen efficiently. you don't
> want to re-heat N??? and O??? or you'd get NOx again.

The cat is going to heat to 2500* F and reform NOx?
Ain't happening.

>
> >
> >> the metal mixes on the
> >> ceramic matrix at each end are slightly different.
> >
> > Yup, that's the way GM did it back in 1982.
> >
> >> http://www.ridelust.com/wp-content/u...cconverter.jpg
> >
> > There is a lot of erroneous information out there and an awful lot that
> > has been taught wrong, even by the OEMs.
>
> true dat!

Which is why I choose to believe what is taught by places like the
National Center for Vehicle Emissions Controls and Safety...
The "Jim" I know there, have met in person, hosted in -my- government
entity emissions testing and training facility 14 years ago at this
point is much better credentialed than the one posting here.

In article > ,
jim beam > wrote:

> On 11/06/2010 08:43 AM, aarcuda69062 wrote:
> > In article<eqGdnSzSFJG66UjRnZ2dnUVZ_gGdnZ2d@speakeasy .net>,
> > jim > wrote:
> >
> >> On 11/06/2010 07:58 AM, aarcuda69062 wrote:
> >>> In >,
> >>> > wrote:
> >>>
> >>>> > wrote in
> >>>> news:nonelson-A83C49.22013905112010@reserved-multicast-range-NOT-delegate
> >>>> d.example.com:
> >>>>
> >>>>> In >,
> >>>>> > wrote:
> >>>>>
> >>>>>> I know the ECM tests the cat's oxidation-side for O2 storage by
> >>>>>> 1) commanding rich for 5 seconds to drain the cat of O2, then
> >>>>>> 2) commanding lean for 5 seconds to load the cat with O2 while
> >>>>>> 3) counting the time that passes before the secondary HO2S flips.
> >>>>>
> >>>>> That hasn't been my observation, but maybe possible that a few
> >>>>> manufacturers that I'm not familiar with have adopted that strategy...
> >>>>
> >>>>
> >>>>
> >>>> A training document I have says that's how Honda does it.
> >>>>
> >>>> My concern has specifically do with an OBD-II Honda, but I had the
> >>>> (evidently erroneous) idea that the general processes were the same
> >>>> across
> >>>> automakers.
> >>>
> >>> I won't dispute that the injector pulse width alternates between
> >>> slightly lean and slightly rich, the 5 second interval though does not
> >>> jive with conventional wisdom or what can be observed when one views O2
> >>> sensor activity on a lab scope and injector on time on a lab scope via a
> >>> low amps probe.
> >>
> >> translation: it's typically faster than 5 seconds.
> >
> > But Teggers' training document says 5 seconds. Are you suggesting that
> > there may be some bad information being offered Jim?
>
> yup. and it wouldn't be the first time in the automotive world. but it
> might be the maximum interval also. i don't know what honda do, but if
> they cycle slower as catalysts degrade and become less responsive, that
> might explain. just guessing.
>
>
> >
> >>
> >>>
> >>>>
> >>>>>
> >>>>>> But how does it test for proper NO (NOx) handling?
> >>>>>
> >>>>> The same way it tests for proper HC and CO handling.
> >>>>
> >>>>
> >>>>
> >>>> Do you mind giving me a quick overview of what your observations are
> >>>> regarding this?
> >>>
> >>> The best opportunity is right after you replace a catalytic converter
> >>> using OEM parts. First step is making sure the PCM has proper fuel
> >>> control including proper airflow measurement. Test drive the vehicle
> >>> under varied operating conditions, typically the upstream O2s will be
> >>> cycling during idle and cruise. The down stream O2s will be outputing
> >>> near 900mv and you may see the occasional swing to low voltage as the
> >>> cat burps off O2 as the cat-con becomes saturated.
> >>>
> >>>> I'm particularly interested in how the ECM uses the secondary O2 sensor
> >>>> to
> >>>> tell the difference between HC/CO and NO handling.
> >>>
> >>> It wouldn't necessarily see a difference such that it would specifically
> >>> identify NOx exceeding the FTP threshold, NOx, CO and HC treatment are
> >>> all part of the same catalytic process.
> >>
> >> no, they're separate processes. there are typically two separate
> >> matricies on a modern catalytic converter - platinum/palladium on the
> >> [front] carbon end, platinum/rhodium on the [rear] nitrogen end.
> >>
> >> again: http://www.ridelust.com/wp-content/u...cconverter.jpg
> >
> > Again: 1980s watered down wisdom not to mention backwards.
>
> show me something [authoritative] that says different then! i've told
> you what i understand the chemistry to be.

Well, I'm not buying you a membership to SAE, so how about you show me
where in the above link they describe a different catalytic process
between the front brick and the rear brick in that cat-con illustration?
They show different feed gasses versus output gasses, hell, they even
colored them differently. Hmmm... they show an input O2 sensor but no
output O2 sensor, is it possible that drawing is too old to be relevant
anymore?

>
> >
> >>
> >>> As that process degrades the
> >>> downstream O2 sensor output begins to mimic the upstream O2 sensor
> >>> output.
> >>>
> >>> This may all change in the future if and when the OEMs begin using
> >>> dedicated NOx sensors in the exhaust stream. Prepare for some
> >>> astronomical sensor prices when that happens...
> >>
> >> let us know when anyone starts using nitrogen sensors...
> >
> > I will.
>
> the point being that they're not in use yet.

You have no point then. Which part of "This may change in the future"
did you not understand?

Word in the pipeline is there may well be a NOx sensor. Then again, we
were supposed to have 42 volt electrical systems by now also.

On 11/06/2010 11:27 AM, aarcuda69062 wrote:
> In article<ssmdneG96Kgd4UjRnZ2dnUVZ_sqdnZ2d@speakeasy .net>,
> jim > wrote:
>
>> On 11/06/2010 08:30 AM, aarcuda69062 wrote:
>>> In article<ZIednWtSc6Jc9UjRnZ2dnUVZ_vkAAAAA@speakeasy .net>,
>>> jim > wrote:
>>>
>>>> On 11/06/2010 06:01 AM, Tegger wrote:
>>>>> > wrote in
>>>>> news:nonelson-A83C49.22013905112010@reserved-multicast-range-NOT-delegate
>>>>> d.example.com:
>>>>>
>>>>>> In >,
>>>>>> > wrote:
>>>>>>
>>>>>>> I know the ECM tests the cat's oxidation-side for O2 storage by
>>>>>>> 1) commanding rich for 5 seconds to drain the cat of O2, then
>>>>>>> 2) commanding lean for 5 seconds to load the cat with O2 while
>>>>>>> 3) counting the time that passes before the secondary HO2S flips.
>>>>>>
>>>>>> That hasn't been my observation, but maybe possible that a few
>>>>>> manufacturers that I'm not familiar with have adopted that strategy...
>>>>>
>>>>>
>>>>>
>>>>> A training document I have says that's how Honda does it.
>>>>>
>>>>> My concern has specifically do with an OBD-II Honda, but I had the
>>>>> (evidently erroneous) idea that the general processes were the same across
>>>>> automakers.
>>>>>
>>>>>
>>>>>>
>>>>>>> But how does it test for proper NO (NOx) handling?
>>>>>>
>>>>>> The same way it tests for proper HC and CO handling.
>>>>>
>>>>>
>>>>>
>>>>> Do you mind giving me a quick overview of what your observations are
>>>>> regarding this?
>>>>>
>>>>> I'm particularly interested in how the ECM uses the secondary O2 sensor to
>>>>> tell the difference between HC/CO and NO handling.
>>>>
>>>> it doesn't and it can't - it's an oxygen sensor. however, the efficacy
>>>> of the cat's carbon and nitrogen catalysis go hand in hand, so if one
>>>> end is degrading, the other is presumed to be degrading too.
>>>>
>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>
>>>>>>> The reduction side
>>>>>>
>>>>>> There is no reduction "side." The oxidation and reduction processes
>>>>>> occur at the same place, same time on the noble metals within the
>>>>>> cat-con.
>>>>>
>>>>>
>>>>>
>>>>> Thank you. I didn't know that.
>>>>
>>>> hopefully because it's not correct. there are two different honeycombs
>>>> in the modern cat. ^^^^^^
>>>
>>> That may have been the design back in the 80s, it isn't how it's done
>>> now. There may be two ceramic bricks but they contain the same metals
>>> and function the same way.
>>
>> untrue.
>>
>> http://en.wikipedia.org/wiki/Rhodium#Catalyst
>> http://en.wikipedia.org/wiki/Palladium#Catalysis
>
> Nothing there to disprove anything I've said so far.
> The picture shows two ceramic bricks, it doesn't however define that
> there roles are separate or different.

read the text dude:

"Rhodium shows some advantages over the other platinum metals in the
reduction of nitrogen oxides to nitrogen and oxygen:[31]

2 NOx → x O2 + N2"

and then:

"palladium forms a versatile catalyst and speeds up hydrogenation and
dehydrogenation reactions, as well as in petroleum cracking. A large
number of carbon-carbon bond forming reactions in organic chemistry
(such as the Heck and Suzuki coupling) are facilitated by catalysis with
palladium compounds"

if that doesn't make sense to you, then this conversation can't achieve
much.


>
>> catalysis occurs at different temperatures too - that's why people are
>> taught too use an i.r. thermometer on a cat to see if it's working
>> correctly.
>
> And that test has long ago been refuted. It is a worthless waste of
> time.

??? as i said before, one reaction runs at a higher temp than the
other. if there's no increase in temp towards the rear of the cat, it's
not working properly. /neither/ reaction will occur unless each portion
of the cat is above its operation temperature.


>
>> i'm not giving you a hard time - it's just that a lot of car tech
>> teaching and information on this subject is "black box" - you don't
>> /need/ to know what's really going on inside, and most people don't know
>> anyway.
>
> Precisely my point. (thank you veddy much).
> Much of what is thought to be true comes from space limited articles in
> Popular Science type magazines. Things like using an IR temperature gun
> to diagnose whether a catalytic converter is working for instance...

non-understanding of catalyst chemistry can lead to fundamental
misunderstandings about fault diagnosis - like failing to use an i.r.
temperature gun to diagnose whether a catalytic converter is working for
instance...


>
>>
>>>
>>>> first one [engine end] deals with carbon. the
>>>> second, [tailpipe end] deals with nitrogen.
>>>
>>> Not only is that statement backwards, it makes no sense.
>>> If the "tailpipe end" of the cat is the NOx reduction part, it wouldn't
>>> be able to contribute oxygen molecules to assist the oxidation of HC and
>>> CO.
>>
>> see above. you need oxyhen to reduce CO to CO???.
>
> Are you asking??? Where in any of this did I state that CO is reduced?
> Do you even understand the difference between reduction and oxidation?

typo. oxidation, not reduction. [i'd have thought that obvious.]


>
> You need oxygen to OXIDIZE HC and CO, if that oxygen can be obtained via
> the reduction of NOx to N2 and O2 it would certainly make sense to do
> that process upstream of the oxidation rather than downstream as you
> assert.
>
>> NOx you can just split
>> - per the wiki link.
>
> Yes, that is the reduction.
>
>>
>>>
>>> But let's go back to the 80s when they did use an air tap into the
>>> cat-con, that tap was typically placed in the center of the cat-con,
>>> does it make sense that a NOx reduction could be accomplished using the
>>> addition of Nitrogen as part of the process?
>>
>> good point, but what i understand is that in modern fuel injection
>> systems, there is sufficient oxygen in the exhaust stream to oxidize the
>> carbon/hydrocarbon content,
>
> There is, it is attached to the nitrogen (NOx).
>
> Rather than state "modern fuel injection systems" substitute 'modern
> catalytic converters.'

no, modern injection systems do not dump excess gas, thus there is
sufficient oxygen in exhaust to ensure conversion. that's why you have
"oxygen" sensors.


>
> If I showed you a O2 sensor signal from a 1982 Chevrolet Caprice side by
> side with an O2 sensor signal from a 2007 Chevrolet Tahoe, you'd be hard
> pressed to distinguish one from the other. The feed gasses are
> essentially the same, the O2 content is the same, it's the catalytic
> converters that have gotten much more efficient. 95% efficiency could
> only be dreamed of 20 years ago.

yes, catalysts /are/ more efficient. but that's helped by the quality
of the injection and combustion feeding it. "sensor signal" doesn't
determine exhaust content - its just a signal that the injection system
utilizes for feedback - it's the injection system that creates the exhaust.


>
> That increased efficiency is due to the things I stated earlier, things
> you said I was wrong about.

i said you were wrong about the cat. and you were.


>
>> so that's done first to raise temperatures
>> that allow the nitrogen conversion to happen efficiently. you don't
>> want to re-heat N??? and O??? or you'd get NOx again.
>
> The cat is going to heat to 2500* F and reform NOx?
> Ain't happening.

then you need to better understand the chemistry! uncontrolled cats
overheat, and apart from causing cat problems in their own right, they
upset the conversion reaction.


>
>>
>>>
>>>> the metal mixes on the
>>>> ceramic matrix at each end are slightly different.
>>>
>>> Yup, that's the way GM did it back in 1982.
>>>
>>>> http://www.ridelust.com/wp-content/u...cconverter.jpg
>>>
>>> There is a lot of erroneous information out there and an awful lot that
>>> has been taught wrong, even by the OEMs.
>>
>> true dat!
>
> Which is why I choose to believe what is taught by places like the
> National Center for Vehicle Emissions Controls and Safety...
> The "Jim" I know there, have met in person, hosted in -my- government
> entity emissions testing and training facility 14 years ago at this
> point is much better credentialed than the one posting here.

whatever dude. if your "jim" doesn't know what the catalyst materials
are and how they work, and he doesn't if you're repeating what he's said
to you, then you're both working with what is to you, a "black box" and
shouldn't make presumptions about what is inside.


--
nomina rutrum rutrum

On 11/06/2010 11:41 AM, aarcuda69062 wrote:
> In article<1fGdnUPh4Y4A4EjRnZ2dnUVZ_vSdnZ2d@speakeasy .net>,
> jim > wrote:
>
>> On 11/06/2010 08:43 AM, aarcuda69062 wrote:
>>> In article<eqGdnSzSFJG66UjRnZ2dnUVZ_gGdnZ2d@speakeasy .net>,
>>> jim > wrote:
>>>
>>>> On 11/06/2010 07:58 AM, aarcuda69062 wrote:
>>>>> In >,
>>>>> > wrote:
>>>>>
>>>>>> > wrote in
>>>>>> news:nonelson-A83C49.22013905112010@reserved-multicast-range-NOT-delegate
>>>>>> d.example.com:
>>>>>>
>>>>>>> In >,
>>>>>>> > wrote:
>>>>>>>
>>>>>>>> I know the ECM tests the cat's oxidation-side for O2 storage by
>>>>>>>> 1) commanding rich for 5 seconds to drain the cat of O2, then
>>>>>>>> 2) commanding lean for 5 seconds to load the cat with O2 while
>>>>>>>> 3) counting the time that passes before the secondary HO2S flips.
>>>>>>>
>>>>>>> That hasn't been my observation, but maybe possible that a few
>>>>>>> manufacturers that I'm not familiar with have adopted that strategy...
>>>>>>
>>>>>>
>>>>>>
>>>>>> A training document I have says that's how Honda does it.
>>>>>>
>>>>>> My concern has specifically do with an OBD-II Honda, but I had the
>>>>>> (evidently erroneous) idea that the general processes were the same
>>>>>> across
>>>>>> automakers.
>>>>>
>>>>> I won't dispute that the injector pulse width alternates between
>>>>> slightly lean and slightly rich, the 5 second interval though does not
>>>>> jive with conventional wisdom or what can be observed when one views O2
>>>>> sensor activity on a lab scope and injector on time on a lab scope via a
>>>>> low amps probe.
>>>>
>>>> translation: it's typically faster than 5 seconds.
>>>
>>> But Teggers' training document says 5 seconds. Are you suggesting that
>>> there may be some bad information being offered Jim?
>>
>> yup. and it wouldn't be the first time in the automotive world. but it
>> might be the maximum interval also. i don't know what honda do, but if
>> they cycle slower as catalysts degrade and become less responsive, that
>> might explain. just guessing.
>>
>>
>>>
>>>>
>>>>>
>>>>>>
>>>>>>>
>>>>>>>> But how does it test for proper NO (NOx) handling?
>>>>>>>
>>>>>>> The same way it tests for proper HC and CO handling.
>>>>>>
>>>>>>
>>>>>>
>>>>>> Do you mind giving me a quick overview of what your observations are
>>>>>> regarding this?
>>>>>
>>>>> The best opportunity is right after you replace a catalytic converter
>>>>> using OEM parts. First step is making sure the PCM has proper fuel
>>>>> control including proper airflow measurement. Test drive the vehicle
>>>>> under varied operating conditions, typically the upstream O2s will be
>>>>> cycling during idle and cruise. The down stream O2s will be outputing
>>>>> near 900mv and you may see the occasional swing to low voltage as the
>>>>> cat burps off O2 as the cat-con becomes saturated.
>>>>>
>>>>>> I'm particularly interested in how the ECM uses the secondary O2 sensor
>>>>>> to
>>>>>> tell the difference between HC/CO and NO handling.
>>>>>
>>>>> It wouldn't necessarily see a difference such that it would specifically
>>>>> identify NOx exceeding the FTP threshold, NOx, CO and HC treatment are
>>>>> all part of the same catalytic process.
>>>>
>>>> no, they're separate processes. there are typically two separate
>>>> matricies on a modern catalytic converter - platinum/palladium on the
>>>> [front] carbon end, platinum/rhodium on the [rear] nitrogen end.
>>>>
>>>> again: http://www.ridelust.com/wp-content/u...cconverter.jpg
>>>
>>> Again: 1980s watered down wisdom not to mention backwards.
>>
>> show me something [authoritative] that says different then! i've told
>> you what i understand the chemistry to be.
>
> Well, I'm not buying you a membership to SAE, so how about you show me
> where in the above link they describe a different catalytic process
> between the front brick and the rear brick in that cat-con illustration?
> They show different feed gasses versus output gasses, hell, they even
> colored them differently. Hmmm... they show an input O2 sensor but no
> output O2 sensor, is it possible that drawing is too old to be relevant
> anymore?

so show me a modern converter that's the single matrix that /you/ think
is used. show which regions of the single matrix are palladium-rich and
which are rhodium-rich.


>
>>
>>>
>>>>
>>>>> As that process degrades the
>>>>> downstream O2 sensor output begins to mimic the upstream O2 sensor
>>>>> output.
>>>>>
>>>>> This may all change in the future if and when the OEMs begin using
>>>>> dedicated NOx sensors in the exhaust stream. Prepare for some
>>>>> astronomical sensor prices when that happens...
>>>>
>>>> let us know when anyone starts using nitrogen sensors...
>>>
>>> I will.
>>
>> the point being that they're not in use yet.
>
> You have no point then. Which part of "This may change in the future"
> did you not understand?

i understand it perfectly - and they're not in use, so i bleating about
them is a red herring.


>
> Word in the pipeline is there may well be a NOx sensor. Then again, we
> were supposed to have 42 volt electrical systems by now also.

red herring.


--
nomina rutrum rutrum

aarcuda69062 > wrote in
:

> In article >,
> Tegger > wrote:


<good info snipped for brevity>

>
>> I'm particularly interested in how the ECM uses the secondary O2
>> sensor to tell the difference between HC/CO and NO handling.
>
> It wouldn't necessarily see a difference such that it would
> specifically identify NOx exceeding the FTP threshold, NOx, CO and HC
> treatment are all part of the same catalytic process. As that process
> degrades the downstream O2 sensor output begins to mimic the upstream
> O2 sensor output.



Well, the reason I asked all this in the first place has to do with Honda's
OBD-II system. In addition to the usual P0420, Honda also has a
manfuacturer-specific DTC (P1420) that is identified in Honda literature as
being:
"NOx Adsorptive Catalyst System Efficiency Below Threshold."

Cosidering that Honda uses ordinary O2-sensors downstream, it got me to
wondering how it was possible for the ECM to know to set P1420 as opposed
to P0420.

Then... I stumbled on a Honda document I've got that explains it. I had
found the document earlier, but in my haste I didn't read it carefully
enough.
It turns out P1420 is set on certain ULEV vehicles that have TWO cats: One
is a normal TWC, the other is a "NOx adsorptive TWC". P1420 means the NOx
cat has failed its OBD-II test.

Thank you for your help.




--
Tegger

In article >,
jim beam > wrote:

> > Nothing there to disprove anything I've said so far.
> > The picture shows two ceramic bricks, it doesn't however define that
> > there roles are separate or different.
>
> read the text dude:
>
> "Rhodium shows some advantages over the other platinum metals in the
> reduction of nitrogen oxides to nitrogen and oxygen:[31]
>
> 2 NOx ??? x O2 + N2"

100% consistent with my first reply to Tegger. i.e., "rhodium shows some
advantages over the other platinum metals." IOWs, all of the noble
metals in the cat react with the pollutants, some work better than
others. Just as my first reply to Tegger stated.

> and then:
>
> "palladium forms a versatile catalyst and speeds up hydrogenation and
> dehydrogenation reactions, as well as in petroleum cracking. A large
> number of carbon-carbon bond forming reactions in organic chemistry
> (such as the Heck and Suzuki coupling) are facilitated by catalysis with
> palladium compounds"
>
> if that doesn't make sense to you, then this conversation can't achieve
> much.

it won't and not because the above doesn't make sense to me, more
because even though you're looking right at it, you refuse to understand
it.

>
> >
> >> catalysis occurs at different temperatures too - that's why people are
> >> taught too use an i.r. thermometer on a cat to see if it's working
> >> correctly.
> >
> > And that test has long ago been refuted. It is a worthless waste of
> > time.
>
> ??? as i said before, one reaction runs at a higher temp than the
> other.

So what? That doesn't mean that the temperature will be higher at the
outlet.

> if there's no increase in temp towards the rear of the cat, it's
> not working properly.

Anecdotal at best. A test based upon more myth than science.

> /neither/ reaction will occur unless each portion
> of the cat is above its operation temperature.

Oh, so your proof is that the cat won't work unless it's at its
operating temperature?
Well DUH!.

>
> >
> >> i'm not giving you a hard time - it's just that a lot of car tech
> >> teaching and information on this subject is "black box" - you don't
> >> /need/ to know what's really going on inside, and most people don't know
> >> anyway.
> >
> > Precisely my point. (thank you veddy much).
> > Much of what is thought to be true comes from space limited articles in
> > Popular Science type magazines. Things like using an IR temperature gun
> > to diagnose whether a catalytic converter is working for instance...
>
> non-understanding of catalyst chemistry can lead to fundamental
> misunderstandings about fault diagnosis

Indeed!

> - like failing to use an i.r.
> temperature gun to diagnose whether a catalytic converter is working for
> instance...

If that really were the case, then the OEs would have mounted a
temperature sensor at the outlet of the cat instead of an O2 sensor to
monitor whether it is working.
Some functioning cats DO have a higher outlet temperature, some
functioning cats however DO NOT have a higher outlet temperature, but to
state that all functioning cats must have a higher outlet temperature is
flat out wrong. It has been tested and proven to not be the case.

If it weren't the case, I'd be happy to state it as such, but
unfortuneately with thousands of temperature tests against thousands of
cat efficiency tests under my belt, I can't bring myself to such
fabrications.

>
> >
> >>
> >>>
> >>>> first one [engine end] deals with carbon. the
> >>>> second, [tailpipe end] deals with nitrogen.
> >>>
> >>> Not only is that statement backwards, it makes no sense.
> >>> If the "tailpipe end" of the cat is the NOx reduction part, it wouldn't
> >>> be able to contribute oxygen molecules to assist the oxidation of HC and
> >>> CO.
> >>
> >> see above. you need oxyhen to reduce CO to CO???.
> >
> > Are you asking??? Where in any of this did I state that CO is reduced?
> > Do you even understand the difference between reduction and oxidation?
>
> typo. oxidation, not reduction. [i'd have thought that obvious.]

No, given the erroneous information you've offered so far, I wouldn't
have chanced it.

>
> >
> > You need oxygen to OXIDIZE HC and CO, if that oxygen can be obtained via
> > the reduction of NOx to N2 and O2 it would certainly make sense to do
> > that process upstream of the oxidation rather than downstream as you
> > assert.
> >
> >> NOx you can just split
> >> - per the wiki link.
> >
> > Yes, that is the reduction.
> >
> >>
> >>>
> >>> But let's go back to the 80s when they did use an air tap into the
> >>> cat-con, that tap was typically placed in the center of the cat-con,
> >>> does it make sense that a NOx reduction could be accomplished using the
> >>> addition of Nitrogen as part of the process?
> >>
> >> good point, but what i understand is that in modern fuel injection
> >> systems, there is sufficient oxygen in the exhaust stream to oxidize the
> >> carbon/hydrocarbon content,
> >
> > There is, it is attached to the nitrogen (NOx).
> >
> > Rather than state "modern fuel injection systems" substitute 'modern
> > catalytic converters.'
>
> no, modern injection systems do not dump excess gas,

Huh? Who said anything about "dumping excess gas?"

> thus there is
> sufficient oxygen in exhaust to ensure conversion. that's why you have
> "oxygen" sensors.

"You have" oxygen sensors because that is currently the cheapest easiest
way of determining if the fuel system is in control. Were it not for
the necessity of emissions monitoring, the O2 sensors could be
eliminated and the engine run solely on the engineers programming.

Apparently, like most, you believe the role of the O2 sensor to be to
tell the PCM how much gasoline to introduce to make the engine run
properly.

> >
> > If I showed you a O2 sensor signal from a 1982 Chevrolet Caprice side by
> > side with an O2 sensor signal from a 2007 Chevrolet Tahoe, you'd be hard
> > pressed to distinguish one from the other. The feed gasses are
> > essentially the same, the O2 content is the same, it's the catalytic
> > converters that have gotten much more efficient. 95% efficiency could
> > only be dreamed of 20 years ago.
>
> yes, catalysts /are/ more efficient.

Yes they are, the reason being is due to what I've described here, not
because of the obsolete beliefs about design that you've offered.

> but that's helped by the quality
> of the injection and combustion feeding it.

Hogwash. Take any engine where the injectors go into batch fire mode as
limp in mode, you won't be able to measure a difference in exhaust
pollutants nor would you feel a difference in driveability.

> "sensor signal" doesn't
> determine exhaust content -

It doesn't? Funny, I repair stuff every day where the exhaust
emissions exceed allowable levels due to a sensor outputing the wrong
value.

> its just a signal that the injection system
> utilizes for feedback - it's the injection system that creates the exhaust.

Really? I fire injectors all the time doing injector balance tests and
there is no exhaust coming from the tailpipe.

>
> >
> > That increased efficiency is due to the things I stated earlier, things
> > you said I was wrong about.
>
> i said you were wrong about the cat. and you were.

I'm certain that you believe yourself. Thing is, you're wrong.

>
> >
> >> so that's done first to raise temperatures
> >> that allow the nitrogen conversion to happen efficiently. you don't
> >> want to re-heat N??? and O??? or you'd get NOx again.
> >
> > The cat is going to heat to 2500* F and reform NOx?
> > Ain't happening.
>
> then you need to better understand the chemistry! uncontrolled cats
> overheat, and apart from causing cat problems in their own right, they
> upset the conversion reaction.

An overheated cat caused by what? Are you going to introduce a
different premise here?

>
> >
> >>
> >>>
> >>>> the metal mixes on the
> >>>> ceramic matrix at each end are slightly different.
> >>>
> >>> Yup, that's the way GM did it back in 1982.
> >>>
> >>>> http://www.ridelust.com/wp-content/u...cconverter.jpg
> >>>
> >>> There is a lot of erroneous information out there and an awful lot that
> >>> has been taught wrong, even by the OEMs.
> >>
> >> true dat!
> >
> > Which is why I choose to believe what is taught by places like the
> > National Center for Vehicle Emissions Controls and Safety...
> > The "Jim" I know there, have met in person, hosted in -my- government
> > entity emissions testing and training facility 14 years ago at this
> > point is much better credentialed than the one posting here.
>
> whatever dude. if your "jim" doesn't know what the catalyst materials
> are and how they work, and he doesn't if you're repeating what he's said
> to you, then you're both working with what is to you, a "black box" and
> shouldn't make presumptions about what is inside.

And your credentials are?

Your last vehicle emissions controls design was when?

It was how long ago that you authored a OE technical service bulletin?

In article > ,
jim beam > wrote:

> > Well, I'm not buying you a membership to SAE, so how about you show me
> > where in the above link they describe a different catalytic process
> > between the front brick and the rear brick in that cat-con illustration?
> > They show different feed gasses versus output gasses, hell, they even
> > colored them differently. Hmmm... they show an input O2 sensor but no
> > output O2 sensor, is it possible that drawing is too old to be relevant
> > anymore?
>
> so show me a modern converter that's the single matrix that /you/ think
> is used.

Cut open any GM light truck converter.
You've done that already, right? Numerous times?


> show which regions of the single matrix are palladium-rich and
> which are rhodium-rich.

Why would YOU think that I think there are different "regions"
especially when I've stated that I know that to not be the case?

You were the one who trotted out 25-30 year old examples where (as I
stated earlier) that may have been the case.

>
> >
> >>
> >>>
> >>>>
> >>>>> As that process degrades the
> >>>>> downstream O2 sensor output begins to mimic the upstream O2 sensor
> >>>>> output.
> >>>>>
> >>>>> This may all change in the future if and when the OEMs begin using
> >>>>> dedicated NOx sensors in the exhaust stream. Prepare for some
> >>>>> astronomical sensor prices when that happens...
> >>>>
> >>>> let us know when anyone starts using nitrogen sensors...
> >>>
> >>> I will.
> >>
> >> the point being that they're not in use yet.
> >
> > You have no point then. Which part of "This may change in the future"
> > did you not understand?
>
> i understand it perfectly - and they're not in use, so i bleating about
> them is a red herring.

"Bleating?" I mentioned it in passing in my reply to Tegger, had I
known it would get your panties bunched up, I probably would have
reconsidered...

>
> >
> > Word in the pipeline is there may well be a NOx sensor. Then again, we
> > were supposed to have 42 volt electrical systems by now also.
>
> red herring.

Red herring in a discussion where someone asked how a NOx failure was
detected?
Please, show as much desperation as you see fit. It's rather amusing.

aarcuda69062 > wrote in
:

> In article >,
> jim beam > wrote:
>

> So what? That doesn't mean that the temperature will be higher at the
> outlet.
>
>> if there's no increase in temp towards the rear of the cat, it's
>> not working properly.
>
> Anecdotal at best. A test based upon more myth than science.



I have an infrared thermometer (it cost $75). When I first got it, one of
the things I tried to find out was whether or not the temperature of the
cat was in fact higher at outlet than inlet.

My results with two cars (both with cats that were known to be working very
well) were inconclusive. The aftermarket cat on my Integra showed COOLER at
output. But I know from my emissions-test results that this cat was doing a
superb job of processing the measured chemicals. The OEM cat on the Tercel
showed about 30F WARMER at output. Both cars were driven the exact same
manner and distance before I did my measuring.



> Some functioning cats DO have a higher outlet temperature, some
> functioning cats however DO NOT have a higher outlet temperature, but
> to state that all functioning cats must have a higher outlet
> temperature is flat out wrong. It has been tested and proven to not
> be the case.
>


--
Tegger

aarcuda69062 > wrote in
:

> In article >,
> jim beam > wrote:
>
>> > Nothing there to disprove anything I've said so far.
>> > The picture shows two ceramic bricks, it doesn't however define
>> > that there roles are separate or different.
>>
>> read the text dude:
>>
>> "Rhodium shows some advantages over the other platinum metals in the
>> reduction of nitrogen oxides to nitrogen and oxygen:[31]
>>
>> 2 NOx ??? x O2 + N2"
>
> 100% consistent with my first reply to Tegger. i.e., "rhodium shows
> some advantages over the other platinum metals." IOWs, all of the
> noble metals in the cat react with the pollutants, some work better
> than others. Just as my first reply to Tegger stated.



Somewhere I have a magazine article written by a particular Ford engineer
(Bill Cannon). This fellow was involved with the very earliest catalytic
converter development efforts from the early-'50s up to the mid-'70s.

In the article, Cannon recounts his research team's quest for a suitable
catalyst. It was discovered very quickly that the mining industry had
already been using platinum-based cats for at least a decade, to control CO
in the mines. But since the proposed automotive device needed to be
compatible with tetra-ethyl lead (mine-gas was unleaded sub-regular),
platinum was unsuitable. This prompted the lengthy search for a different
material.

The government body that drove all this in the first place (can't remember
the name of it) was initially not concerned with CO, only HCs, which set
the focus for the search.

After many years of testing and research -- which revealed that a very
large number of metals had considerable HC-catalyst properties -- they
settled on tungsten. The test tungsten cats survived satisfactorily for
80,000 miles, this in a day when cars rarely went much past 100,000 miles.
Cannon gives charts which show the relative performance of the various
tested metals.

Unfortunately, by that time, the government body (can't remember if it was
the EPA by this point) suddenly decided that CO must be controlled as well.
This junked 20-years of research, and forced everybody back to the original
metal, platinum. And that's why they started to phase-out leaded gas.

Since that time, palladium and rhodium have been adopted as well.

This is all from memory, mind you. I'd need to go through a 2-ft stack of
magazines to find this article.


--
Tegger