on second thought I drive a rover so I obviously don't care too much about how efficient my CC is!

 

too funny... hell, I don't even have any cats... or a resonator. Just one lonely center muffler

 

All I am saying is that all 4 have a purpose in engine management.

I agree that RAW fuel kills cats. I had an bad injector which lead to the cat destruction. proper atomization and still burning fuel post combustion is what heats up the cats.

And whoever said I was wrong - I was using a basic statement. The compounds react to oxidation, which is based on temperature, so in very basic term, they measure temperature. That is what I meant..

Again, though... my whole point is that the post cat O2's have a function other than turning on a light...

 

I must disagree with this statement. My brother-in-law dumped a gallon of raw fuel on a cat and it did not die. It did, however, lose all it's hair...

 

Not trying to be a dick, but that's still wrong. O2 sensors detect a difference in oxygen between two samples. The catalyst that performs this works better at a certain temperature range, but ideally the o2 sensor would be HELD at that temp to give better readings. Any temperature correlation is ideally factored out of the sensor. There isn't any correlation between the exhaust temperature and the detected difference as long as the probe is operating in its desired range. Its possible you could use an o2 sensor as a thermometer if you really wanted to extrapolate all the variables and create the proper look up tables and do the math, but that doesn't mean it is simply a high temperature thermometer. Thermometers measure absolute temperature. O2 sensors measure the difference in oxygen content between two samples.

 

LOL thats awesome!

 

Bee dump dump clank.

 

John Bonham you are not...

 

This is a good read, wish I had gotten home from work sooner...good work Cosmic.

As for O2's reading O2 levels, this is why our trucks throw a O2 code when the spark plugs start to wear out or you have mis fires, a incomplete combustion sends more raw fuel downstream and the O2's go out of wack and BAM!, check engine light with a O2 code.

I saw a episode of "Deconstructed" on the Discovery? Channel, they took a catalytic converter apart and they said it takes 5-6 miles of driving for one to reach full operating efficiency.

I would tend to think that cat's die quicker with frequent short trips, but thats just my opinion.

As for the engine running rich when cold (cold engines need more fuel [think full choke] and the cats need raw fuel to reach temp) last winter I did a experiment.
I kept track of my MPG for one week, I let the truck warm up for 10 min before leaving for work and 10 min before heading home.
Did this for 5 days.
Then the next week I did not let the truck warm up, I just drove it gently until fully warm, again both to work and home from work.
I drove the exact same route, used the same fuel, no deviation for the two weeks.
Warm up MPG ~15.
Non warm up MPG ~10.

As for the post cat O2's, how do you think they did it before 4 O2's were required?
Do all pre-OBDII cars run rich all the time?
I have done the research, post cat O2's do nothing for engine fueling.
I too used to believe that you needed all 4 O2's and that O2's were nothing more than thermometers...I was wrong.

This is very good Cosmic, keep it up.

 

You are correct, they basically work by providing a nice home for a reaction to take place and use a honeycomb structure meant to maximize the surface area available. Their performance profile follows a nearly linear dropoff as surface area is lost over the life of the converter.