Inside a catalytic in use

[Ryan]

This was interesting, and shows why our exhaust glow so damn red when a plug cap dies and one cylinder is just dumping fuel.
https://youtu.be/ekQcy6GN1pM

[oldbike54]

 Interesting .

 Dusty

[Rough Edge racing]

This was interesting, and shows why our exhaust glow so damn red when a plug cap dies and one cylinder is just dumping fuel.
https://youtu.be/ekQcy6GN1pM

 Newer vehicles have a feature to save the catalytic convertor when it starts to overheat....Picture a PU truck pulling a trailer up a long steep grade at 65 mph, the engine running at large throttle opening and high rpm...If the convertors reach a certain temperature, the engine management system actually greatly enrichens the mixture to cool the convertor(s)....

[Triple Jim]

Newer vehicles have a feature to save the catalytic convertor when it starts to overheat....Picture a PU truck pulling a trailer up a long steep grade at 65 mph, the engine running at large throttle opening and high rpm...If the convertors reach a certain temperature, the engine management system actually greatly enrichens the mixture to cool the convertor(s)....

How would that work when greatly enriching the mixture in itself causes the converter to get hot?

[Rough Edge racing]

How would that work when greatly enriching the mixture in itself causes the converter to get hot?

  No extra air so no combustion in the convertor, a rich mixture is cooler......Same principle was used on high output air cooled WW2 aircraft engines, overfueling used to cool the combustion process to prevent detonation...

  I have more info but read this, scroll down to closed loop convertor protection mode...

   https://books.google.com/books?id=rhmIDwAAQBAJ&pg=PA299&lpg=PA299&dq=rich+fuel+mixtures+to+keep+catalytic+convertors+from+overheating&source=bl&ots=xMAUgZvrvq&sig=ACfU3U2y-P7KKEV70799teInra_utzk0pA&hl=en&sa=X&ved=2ahUKEwjh-u6XyuLmAhWQQs0KHVA5DnUQ6AEwF3oECBQQAQ#v=onepage&q=rich%20fuel%20mixtures%20to%20keep%20catalytic%20convertors%20from%20overheating&f=false

[n3303j]

Newer vehicles have a feature to save the catalytic convertor when it starts to overheat....Picture a PU truck pulling a trailer up a long steep grade at 65 mph, the engine running at large throttle opening and high rpm...If the convertors reach a certain temperature, the engine management system actually greatly enrichens the mixture to cool the convertor(s)....

Odd, my Dodge Cummings purges particulates out of the system by burning them out on hot sections of a run. Nothing like pulling the 5th wheel up the mountains to keep the system clean.

If the truck doesn't see a hot section of the run suitable for a purge it will start firing injectors on the exhaust stroke to drive the cat temperature up to the required purge temperature. It's odd watching mileage drop from 17 per gallon to 9 per gallon for a 75 mile period.

Guess DEF takes care of all that now.

[Rough Edge racing]

Odd, my Dodge Cummings purges particulates out of the system by burning them out on hot sections of a run. Nothing like pulling the 5th wheel up the mountains to keep the system clean.

If the truck doesn't see a hot section of the run suitable for a purge it will start firing injectors on the exhaust stroke to drive the cat temperature up to the required purge temperature. It's odd watching mileage drop from 17 per gallon to 9 per gallon for a 75 mile period.

Guess DEF takes care of all that now.

 What year is your truck?All that stuff didn't exist on Diesels until emissions controls got strict and electronic injectors....The new Diesels have become very complicated, so much so that both Ford and GM have introduced new larger more powerful gas engines for 2020...Of interest is the new Ford 7.3 gas engine is designed not to need overfueling to protect the catalytic convertors during periods high power loading...

[Groover]

I'm surprised combustion engines can actually function with that type of restriction....

[n3303j]

What year is your truck?All that stuff didn't exist on Diesels until emissions controls got strict and electronic injectors....The new Diesels have become very complicated, so much so that both Ford and GM have introduced new larger more powerful gas engines for 2020...Of interest is the new Ford 7.3 gas engine is designed not to need overfueling to protect the catalytic convertors during periods high power loading...

Truck is a 2008 Ram 3500 6.7 Cummins
'07-'08 were the "experimental years" with that emissions system.
The emissions additions made the 1 liter larger engine produce less horsepower, torque and fuel economy than its smaller predecessor.
After '08 Dodge got the some of the quirks out of the system.
Then DEF became law (I think around '12). Not a clue what that's all about.

[Murray]

Enriching a diesel makes it run hotter opposite to spark ignition motors.