tom picknose failed second year apprentice
>>> You should know why EGR controls NOX, do you not? Answer that and we will
>>> move forward.
>> Yes, I know how EGR controls NOX. I'm not arguing this with you.
>Good then you know that introducing more inert gas to the intake air does what?
>Lowers combustion temp's. Now you have a plugged exhaust. Exhaust does not
>leave. Because of that there is not a pressure drop or very little pressure drop
>in the cylinder because it's still full or partially full. Because of that
>little to no pressure drop little to no fresh air enters the cylinder at intake
>stroke. The cylinder is full of mostly inert gas. How well is combustion process
>going to be? Not very well. Just like when you dilute the intake air with a
>little exhaust you drop the combustion temp's, with a lot of exhaust you get
>even less combustion temp's. Low enough that the cooling system is way over
>capicity to do a real nice job of taking out any built up heat.
>> What I have seen is exhaust manifolds glowing bright orange in broad daylight
>> due to exhaust restriction, along with (to the driver) a sharp increase in
>> cooling system temperature.
>> The most vivid recollection was on a 1966 FE (428 cid) powered motor
>> home.(the first case I ever saw). The H pipe was of a triple wall design and
>> the inner "wall" collapsed, mostly plugging the exhaust flow. The only
>> noticible concern was overheating and a slight lack of power. (Along with
>> excessive heat radiating from the doghouse).
>Slight lack of power with a pipe that had collapsed makeing a pig plug? What do
>you take me for?
u just proved it yourself
The catalytic converter consists of small amounts of precious metal
deposited on a ceramic substrate. The failure mode is chemical ie
poisoning the precious metal with contminants like lead in gas or
mechanical, breaking up the ceramic substrate. Plugging is mechanical
failure (the ceramic substrate gets broken up into small fine pieces)
normal thermal cycling will eventually cause the ceramic to start to
crumble. Cats are designed to last 100k miles minimum but if the car
is driven only on short trips (every trip thermal cycles the cat) then
early failure could result.
Second, thermal shock will cause the ceramic to break up. Having the
car (and cat) up to operating temperature and driving thru deep water
for a long enough period will cause a thermal shock that could cause
Unlike the earlier two-way converters that could perform their job
relatively efficiently with a lean fuel mixture, the catalyst inside a
three-way converter that reduces NOX requires a rich fuel mixture. But
a rich fuel mixture increases CO levels in the exhaust. So to reduce
all three pollutants (HC, CO and NOX), a three-way converter requires
a fuel mixture that constantly changes or flip flops back and forth
from rich to lean. This, in turn, requires feedback carburetion or
electronic fuel injection, plus an oxygen sensor in the exhaust to
keep tabs on what’s happening with the fuel mixture.
Converters may also fail if they get too hot. This can be caused by
unburned fuel in the exhaust. Contributing factors include a rich fuel
mixture, ignition misfire (a fouled spark plug or bad plug wire) or a
burned exhaust valve that leaks compression. Fuel in the exhaust has
the same effect as dumping gasoline on a bed of glowing embers. Things
get real hot real fast. If the converter’s temperature climbs high
enough, it can melt the ceramic substrate that supports the catalyst
causing a partial or complete blockage inside. This increases
backpressure, preventing the engine from exhaling and robbing it of
power. Fuel consumption may shoot up and the engine may feel sluggish
at higher speeds. Or, if the converter is completely plugged, the
engine may stall after starting and not restart.
now lets see
i bet you get a rich condition
coverter makes heat
engine is more loaded
condition gets richer
hey pick nose
yor failed yeat too
no canada for you