Has anyone tried making/using a catalytic converter warmer?

[roflwaffle]

Originally Posted by dichotomous

anyways, like I said I am likely to be putting on a high flow cat, should keep my exhaust pretty free flowing and increase the efficiency of the motor, using less gas and cleaning the gas that is used (the 2.25" pipe models are designed for a 5.7l V8, my 2.0l I4 should be well scrubbed). I am not advocating anyone remove their catalytic converter.

Putting a cat that's too large will increase light off times and pollution compared to a cat that's the right size. Not that you shouldn't replace a leaky beat-up one, just that using something too big will probably result in a significant emissions increase on startup.

Originally Posted by dichotomous

now dont get me started on the polution that CREATING the cat costs, there is way more pollution and horrible things going in the environment from the production of platinum and rhodium and the ceramics that make up a cat, way more than it will prevent from my little car or bike running 30,000mi a year.....

Proof or I call B.S.

[roflwaffle]

Originally Posted by Christ

Problem with pre-heating the cat - Engines run slightly richer during warm up as a means to heat the cat quickly. A cold cat can handle the excess fuel without gross pollution.

A cold cat is what results in the most pollution.

Originally Posted by Christ

Pre-warmed cat + cold engine == engine still running rich and cat over heating.

AFAIK that shouldn't happen. The ECU should start reading info from the post cat oxygen sensor within a few seconds and if the mixture is too rich lean it out.

Originally Posted by Christ

At least I think. I have no proof to back this up, other than what I know about excess fuel entering the catalyst, and causing it to heat up substantially.

It typically needs that heat to function properly. What can kill it is running rich all the time which will generate too muchheat and start to melt the honeycomb the catalyst is on.

[Christ]

Originally Posted by roflwaffle

AFAIK that shouldn't happen. The ECU should start reading info from the post cat oxygen sensor within a few seconds and if the mixture is too rich lean it out.

You assume, by this statement, that all cars are OBD-2... not all cars have a post cat O2 sensor, and even a large number of those that do, only use it to see whether the catalyst is actually doing something, not to adjust the fuel/air mixture.

IIRC, it wasn't until the advent of OBD-2b that the post-cat O2 sensor's signal was used to help adjust AFR in comparison to the signal from the pre-cat sensor.

[Christ]

Originally Posted by roflwaffle

Putting a cat that's too large will increase light off times and pollution compared to a cat that's the right size. Not that you shouldn't replace a leaky beat-up one, just that using something too big will probably result in a significant emissions increase on startup.

The cat he's talking about is CARB exempt... so it can't be all that bad.

[tasdrouille]

Christ,

Platinum catalytic converters cans sustain over 1600 F continuously. During normal driving my EGT are 700-900 F at the first o2 sensor in my elantra. To be frank, I never saw it go above 1000 F. I doubt a bit that a rich running engine at startup could make an already hot cat exceed 1600 F.

[Christ]

I wasn't really referring to damaging the cat.. the heatshield on the cat is only meant to be effective in it's normal operating range... and it's normally in pretty close proximity to the body... heat shield fails, it heats up the body, and 1600* translates to cabin fire.

How do I know this? I had to replace the carpet in 2 cars because I didn't think running too rich for any period of time would cause a problem. Then I found out that excess fuel causes the cat to heat up more than it should, and it kinda dawned on me at that point.

Originally Posted by 2carpros.com

Question: 2004 Nissan Sentra 1.8_mileage: 41,000. I just bought a low mileage Nissan Sentra. The fuel economy is terrible, not what I would expect from a V6. It sometimes hesitates to start. It warms up very fast but the interior gets unusually warm as though the catalytic converter is working overtime. The excess heat comes up through the floor. What is the likely cause and solution to this problem?

Answer: Scan computer for fault codes. You will probably find one indicating that your engine is running too rich which causes the catalytic converter to overheat. Check the fuel pressure regulator and check for faulty fuel injectors.

And more information:
Catalytic Converter

[theunchosen]

I'm going to say it here as well. . .but I am going to summarize.
In putting the gasoline in your engine well over 150 lbs of CO2 are created from the refining and transport to you. The most damage you can possible generate in CO2 is a theoretical max of 20 lbs. plus a few tiny amounts of particles from the tailpipe and from the power plants you drop 1lb of expent hazardous to the environment(much more so than your measely .odd grams of anything) coal.
Better Fuel economy at ANY cost = cheaper= more ecologically friendly. the other post is on the VW Jetta TDI vs gas. . .I'll edit a link into it
http://ecomodder.com/forum/showthrea...ison-6184.html
its post 19. . .

[roflwaffle]

Originally Posted by Christ

The cat he's talking about is CARB exempt... so it can't be all that bad.

Well, CARB exempt for a much larger engine anyway. The only way to find out would be through testing but I'm pretty sure a cat designed for a larger engine will take longer to light off than one designed for a specific engine size. It could be designed for a range of displacements, and in that case it should work o.k. but if it's specifically designed for use w/ a larger engine I have my doubts.

[roflwaffle]

Originally Posted by Christ

You assume, by this statement, that all cars are OBD-2... not all cars have a post cat O2 sensor, and even a large number of those that do, only use it to see whether the catalyst is actually doing something, not to adjust the fuel/air mixture.

IIRC, it wasn't until the advent of OBD-2b that the post-cat O2 sensor's signal was used to help adjust AFR in comparison to the signal from the pre-cat sensor.

Even then it still wouldn't get hot enough over warm up. We need obscenely rich, like unburnt gas all the time, to heat up a cat to the point where it's damaged. Not just a little richer during warm-up. At least AFAIK.

[Christ]

Read the link. Being overheated for an extended period, even just slightly overheated, can damage the cat.

And the hi flow cat that he's talking about is CARB exempt as an aftermarket replacement for *any* vehicle. It's listed as a Hi-flow universal cat. FYI.

Check Magnaflow's website for it, in case I'm wrong.