help exhaust glowing

jeffcoslacker wrote:

> Steve Wrote:
>
>>Kevin Bottorff wrote:
>>
>>
>>>jeffcoslacker > wrote in

<snip>

>>>>if external air is admitted before sensing? I'm fascinated.
>>
<snip>

>What did you think I meant by multiple sensors?


My bad- I missed the "before sensing" clause. Indeed the whole point of
multiple O2 sensors is to have at least one of them always able to sense
the raw O2 content of the exhaust coming out of the engine before its
either corrupted by the reduction catalyst or by air injection. The
downstream sensor measures how well everything works as a system, and
enables OBD-II level diagnostics. IOW, the upstream sensor controls the
fuel trim, the downstream sensor tells if the emission controls are
working. But the whole point is that, even today, air injection is still
used to make the oxidation catalyst perform better. LESS air is used,
and the big belt-driven air pump is indeed almost (if not) extinct. But
air injection lives on.

But getting back to the ORIGINAL post- I still say that a glowing
exhaust is most likely the result of a misfiring cylinder (or several)
since that is the process that dumps ready-to-burn air/fuel mix into the
exhaust stream.

Steve Wrote:
> jeffcoslacker wrote:
>
> > Steve Wrote:
> >
> >>Kevin Bottorff wrote:
> >>
> >>
> >>>jeffcoslacker > wrote in
>
> <snip>
>
> >>>>if external air is admitted before sensing? I'm fascinated.
> >>
> <snip>
>
> >What did you think I meant by multiple sensors?
>
>
> My bad- I missed the "before sensing" clause. Indeed the whole point of
> multiple O2 sensors is to have at least one of them always able to
> sense
> the raw O2 content of the exhaust coming out of the engine before its
> either corrupted by the reduction catalyst or by air injection. The
> downstream sensor measures how well everything works as a system, and
> enables OBD-II level diagnostics. IOW, the upstream sensor controls the
> fuel trim, the downstream sensor tells if the emission controls are
> working. But the whole point is that, even today, air injection is
> still
> used to make the oxidation catalyst perform better. LESS air is used,
> and the big belt-driven air pump is indeed almost (if not) extinct. But
> air injection lives on.
>
> But getting back to the ORIGINAL post- I still say that a glowing
> exhaust is most likely the result of a misfiring cylinder (or several)
> since that is the process that dumps ready-to-burn air/fuel mix into
> the
> exhaust stream.

It could be...I just figured that most people would notice something
strange and the post would be like "My car has been running like crap
and now..." or "I've been getting terrible gas mileage, and now my
manifold is glowing..."...but perhaps I assume too much...

Anyways, you got me on that secondary injection...wasn't part of my
understanding of the system, and I apologize for doubting you.


--
jeffcoslacker
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silicon212 > wrote in
:


>
> The Russian cars of the 80s had cats?
>
>


In Canada they did after a certain point.

--
TeGGeR®

TeGGeR® > wrote:
:
>
>> The Russian cars of the 80s had cats?
>
>In Canada they did after a certain point.

Until they fell off, anyway. Like everything else on the Lada.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

So very likely the exhaust system or at least the converter(s) are
already damaged. Excessive fuel from cyl miss-fire; most likely
multiple miss-fire is the likely cause. Rising combustion temps will
increase exhaust temp. Excessive exhaust temp that hinders combustion
will in most cases lower combustion temp.


--
JustSayGo
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"TeGGeR®" wrote:
>
> silicon212 > wrote in
> :
>
> >
> > The Russian cars of the 80s had cats?
> >
> >
>
> In Canada they did after a certain point.
>
> --
> TeGGeR®

My 86 Jeep CJ7 didn't come with a cat, the 87's did though.

Maybe that's the cut off year?

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Mike Romain > wrote in
:

> "TeGGeR®" wrote:
>>
>> silicon212 > wrote in
>> :
>>
>> >
>> > The Russian cars of the 80s had cats?
>> >
>> >
>>
>> In Canada they did after a certain point.
>>
>
> My 86 Jeep CJ7 didn't come with a cat, the 87's did though.
>
> Maybe that's the cut off year?




Could be. Leaded gas was banned in Canada around about 1987.

Some cars had cats earlier. The Mazda RX-7 had one for 1981. In that case,
it enabled Mazda to get rid of the trouble-prone thermal reactor.


--
TeGGeR®