How do you know if the catalytic converter is bad?

[alazo1]

The engine on the maxx470 is idleling funny. rpm revs up and down. It will do it in medium speed as well. When I bring the choke up a little all seems well but this has never happened before. Fuel filter has been changed. Spark plugs have been changed, air filter is a few months old. I took the fuel line out and it's pumped about 20 ounces in a minute so that seems ok.

The catalytic converter is making rattling noises. Can this be the problem.

How do you know when the catalytic converter is bad? What kind of symptoms will happen when it's going?

thanks,
Albert

 

[Bob Foster]

Pound on it with a rubber mallet if it falls off its broken.

They get plugged up and usually have lots of crap rolling around in them and you can hear the junk bouncing around in them when you hit them. Its quite normal to hear some stuff bouncing around in them but if you hear a bunch it could be bad.

An inexpensive place to get them is http://www.rockauto.com

They usually stink at start up when they're bad too.

 

[Lee Stockwell]

http://www.bearriverconverters.com/data/CatOpp.pdf

 

[The Great Oz]

If you hit it and it rattles, the engine has been running too lean. In the biz they call this the "box of rocks" because the material inside is broken and the loose material can plug the exhaust flow. Exhaust repair shops won't warranty a replacement unless you can show them auto shop certification that the engine is now running properly.

If you're running rich they plug up and don't make any noise.

Bad oxygen sensors are often the cause.

 

[rwcarpet]

The irradic RPM's sound like a vac leak??

My 405 ran with a cat and would not run well if the air pump was bad. Does the Max use an air pump?

 

[alazo1]

Thanks guys. I have to take this thing in. It's running like crap. I think the blower is going too.

Albert

 

[alazo1]

Well, today the tm is running fine. I took it in anyways and was told that it could have been a bad batch of gasoline. eitherway hopefully it will keep runnning ok.

The blower is another thing all together

BTW, the machine does have an airpump.