Catalytic converter additive

Due to a malfunction, cylinder 3 was not firing in my auto and dumping
raw fuel in the cylinder .
The problem was fixed, but now the check engine light is continuously
showing that the catalytic converter is defective. Does any one know
of an additive that might reverse this problem? Cats are expensive
(:= ]

Larry

On Jun 17, 2:36*pm, iconlarry > wrote:
> Due to a malfunction, cylinder 3 was not firing in my auto and dumping
> raw fuel in the cylinder .
> The problem was fixed, but now the check engine light is continuously
> showing that the catalytic converter is defective. Does any one know
> of an additive that might reverse this problem? Cats are expensive
> (:= *]
>
> Larry

you sure it's not just a bad O/2 sensor???

"iconlarry" > wrote in message
...
> Due to a malfunction, cylinder 3 was not firing in my auto and dumping
> raw fuel in the cylinder .
> The problem was fixed, but now the check engine light is continuously
> showing that the catalytic converter is defective. Does any one know
> of an additive that might reverse this problem? Cats are expensive
> (:= ]
>
> Larry

How far have you run it since this happened?
A good run on the highway might help, but if it doesn't you may
be looking at an oxygen sensor rather than the catcon.

Now, I have experienced that some cars, particular some Chrysler
Corp models, are harder on converters than others. Some of those
things just collapse internally.

iconlarry > wrote:
>Due to a malfunction, cylinder 3 was not firing in my auto and dumping
>raw fuel in the cylinder .
>The problem was fixed, but now the check engine light is continuously
>showing that the catalytic converter is defective. Does any one know
>of an additive that might reverse this problem? Cats are expensive
>(:= ]

No, but a good long highway drive might get the thing hot enough to burn
out contamination. Then again, it might not.

It might also be possible to drop it, clean it out with acetone, and put
it back. Then again, it might not.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

iconlarry > wrote in news:3084c9a4-a68d-42fa-980d-
:

> Due to a malfunction, cylinder 3 was not firing in my auto



What kinda car?



> and dumping raw fuel in the cylinder .



Oooh, bad, BAD. Raw fuel like that is death to the cat.

Depending on how long you've been driving it that way, the raw fuel may
have sintered the cat's surface to the point where it fails the OBD-II
threshold test.




> The problem was fixed, but now the check engine light is continuously
> showing that the catalytic converter is defective. Does any one know
> of an additive that might reverse this problem? Cats are expensive


What's the actual code you're getting? P0420?


--
Tegger

"Tegger" > wrote in message
...
> iconlarry > wrote in news:3084c9a4-a68d-42fa-980d-
> :
>
>> Due to a malfunction, cylinder 3 was not firing in my auto
>
>
>
> What kinda car?
Picky, picky, picky....
>
>
>
>> and dumping raw fuel in the cylinder .
>
>
>
> Oooh, bad, BAD. Raw fuel like that is death to the cat.
>
> Depending on how long you've been driving it that way, the raw fuel may
> have sintered the cat's surface to the point where it fails the OBD-II
> threshold test.
>
>
>
>
>> The problem was fixed, but now the check engine light is continuously
>> showing that the catalytic converter is defective. Does any one know
>> of an additive that might reverse this problem? Cats are expensive
>
>
> What's the actual code you're getting? P0420?
>
>
> --
> Tegger

On 06/17/2011 12:29 PM, Scott Dorsey wrote:
> > wrote:
>> Due to a malfunction, cylinder 3 was not firing in my auto and dumping
>> raw fuel in the cylinder .
>> The problem was fixed, but now the check engine light is continuously
>> showing that the catalytic converter is defective. Does any one know
>> of an additive that might reverse this problem? Cats are expensive
>> (:= ]
>
> No, but a good long highway drive might get the thing hot enough to burn
> out contamination. Then again, it might not.
>
> It might also be possible to drop it, clean it out with acetone

anything acetone can dissolve, heat will burn so no point using it.

when run too hot because of raw fuel dump, the catalytic metal wash
diffuses too deep into the ceramic matrix for it to work. i'd clear the
code, then go for an italian tune-up. if the code returns,
check/replace the sensors, and if they don't resolve the prob, replace
the cat.


>, and put
> it back. Then again, it might not.
> --scott


--
nomina rutrum rutrum

jim beam > wrote in
t:


>
> when run too hot because of raw fuel dump, the catalytic metal wash
> diffuses too deep into the ceramic matrix for it to work.



The surface of the cat's element is wispy, like cotton candy. That gives it
a tremendous amount of surface-area for the physical volume of the element.
Remember that cats work on adsorption principles, not absorption.

When excess amounts of raw gas are admitted to the cat, the wisps overheat
and melt, just like when cotton candy gets wet. This action (called
"sintering") greatly reduces the available surface area, and thus the
effectiveness of the cat. That's ultimately what sets a P0420 on cars with
excess HC going into the cat.

The cat is meant as a clean-up device ONLY; its life depends on proper
combustion in the first place.



--
Tegger

On 06/19/2011 07:46 AM, Tegger wrote:
> jim > wrote in
> t:
>
>
>>
>> when run too hot because of raw fuel dump, the catalytic metal wash
>> diffuses too deep into the ceramic matrix for it to work.
>
>
>
> The surface of the cat's element is wispy, like cotton candy.

yes it's porous, but cotton candy, it ain't. imagine you had a bucket
of pebbles, and you stuck them all together with a wash of pva glue.
there would be holes between the pebbles that you could pass liquids and
gasses through, but they're stuck together at their contact points to
give them the function of a larger contiguous solid on the macro scale.
no "wisps", just lots of very tiny pebbles.


>That gives it
> a tremendous amount of surface-area for the physical volume of the element.

indeed.


> Remember that cats work on adsorption principles, not absorption.

well, adsorption is certainly part of the catalytic process, but
catalysis is not simply adsorption - the glass in your windows are
exposed to air for instance, and they have an adsorbed layer of air
molecules as a result [and lots of other stuff] - but there is no
catalysis going on.

http://www.thenakedscientists.com/HT...interview/569/


>
> When excess amounts of raw gas are admitted to the cat, the wisps overheat
> and melt, just like when cotton candy gets wet. This action (called
> "sintering") greatly reduces the available surface area, and thus the
> effectiveness of the cat.

ok, sintering does indeed reduce surface area, but it's one heck of a
stretch to call it melting, even on the micro scale. and sintering is
not the only thing going on to kill the cat's efficacy.

"sintering" is most commonly a diffusion process which happens in the
solid state.

http://en.wikipedia.org/wiki/Atomic_diffusion

very very briefly, if you have two solid pebbles touching, and you heat
them [but to a temperature well below melting], you'll get diffusion at
the contact point, and that forms a bond. if sufficient [function of
time and temp], that bond can hold large structures of these pebbles
together, which is where pottery and "ceramics" come from. the longer
and hotter the heating process, the more diffusion, and more
densification. [that's why cheap cups and plates weigh less than
expensive ones. and why overheated pottery sags and deforms because of
liquefaction.]

there are "sintering-like" processes which involve micro liquefaction,
but they're not employed in auto catalyst substrate manufacture afaik.

[these cites below are kind sorta there, but they're technician-grade
and don't adequately explain the relevance and mechanism of the
diffusion process.]
http://en.wikipedia.org/wiki/Sintering
http://en.wikipedia.org/wiki/Powder_metallurgy


> That's ultimately what sets a P0420 on cars with
> excess HC going into the cat.
>
> The cat is meant as a clean-up device ONLY; its life depends on proper
> combustion in the first place.

automotive catalytic converters can handle a lot of abuse. what they
can't stand is poisoning, e.g. lead or other agents, or overheat for
prolonged periods. poisoning kills them because the reagents get bound
into compounds that are no longer catalytically active. excess
heat/time kills them because the surface wash of reagents diffuses into
the substrate and reaction rates slow to the point of ineffectiveness.
that's also why a leaking head gasket can kill a cat, especially on a
honda where it can go unnoticed for an extended period - silicates coat
the cat surface "burying" the active metals.


--
nomina rutrum rutrum

jim beam > wrote in
t:

> On 06/19/2011 07:46 AM, Tegger wrote:
>> jim > wrote in
>> t:
>>
>>
>>>
>>> when run too hot because of raw fuel dump, the catalytic metal wash
>>> diffuses too deep into the ceramic matrix for it to work.
>>
>>
>>
>> The surface of the cat's element is wispy, like cotton candy.
>
> yes it's porous, but cotton candy, it ain't. imagine you had a bucket
> of pebbles, and you stuck them all together with a wash of pva glue.
> there would be holes between the pebbles that you could pass liquids
> and gasses through, but they're stuck together at their contact points
> to give them the function of a larger contiguous solid on the macro
> scale.
> no "wisps", just lots of very tiny pebbles.



OK, porous pebbles, then. I guess "cotton candy" was too wispy an analogy.

<http://openlearn.open.ac.uk/mod/oucontent/view.php?id=398548&section=1.5.2>



>
>
>>That gives it
>> a tremendous amount of surface-area for the physical volume of the
>> element.
>
> indeed.
>
>
>> Remember that cats work on adsorption principles, not absorption.
>
> well, adsorption is certainly part of the catalytic process, but
> catalysis is not simply adsorption - the glass in your windows are
> exposed to air for instance, and they have an adsorbed layer of air
> molecules as a result [and lots of other stuff] - but there is no
> catalysis going on.



The reactions occur on the surface of the washcoat, so "adsorption"
is correct.



>
> http://www.thenakedscientists.com/HT.../interview/569
> /




That page tells you nothing about the ceramic substrate, which is the
"wispy" part.

<http://openlearn.open.ac.uk/mod/oucontent/view.php?id=398548&section=1.5.2>


--
Tegger