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Old 06-21-04, 04:06 PM   #1
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Air Pump

I've seen a lot of people say that disconnecting the air pump will burn out the catalytic converter. I don't see how this is possible.

The air pump provides fresh air to the cat to oxydize the HC and CO in the exhaust. The oxidation process is exothermic, it gives off heat. The reason the air pump is there is because there aren't enough O atoms released in the first catalyst (the reducer, NOx to N2 and O2) to oxydize all of the HC and CO atoms and more O2 needs to be introduced.

The only thing that happens when you disconnect the air pump is that there won't be enough O2 to fully oxydize the exhaust and you'll fail emmisions.

Has anyone actually removed the airpump and burned out a cat?
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Old 06-21-04, 04:35 PM   #2
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I've done the 1st half of disconnecting mine (and it made a HUGE positive power increase on just a typical stock 1st gen GSL) but Ari up at Rotary Performance in Garland, TX told me it would clog it up with carbon. He said depending on the driving habits (really fast in my case) and the condition of the engine, it may be an average of 6k miles or 6 months. I haven't noticed any differences yet and it's been at least 2000 miles since I disconnected mine... I just need to get my new exhaust system in to cut the damn thing off. (the CAT that is)

Also, I've heard in these forums that it will "melt the cat" and clog it up and who knows what else, so, for what it's worth you know as much as I do (and obviously you know more about the oxidation and stuff that I'm clueless about.) Good question though... I'm gonna be watchin' this thread closely.
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Old 06-21-04, 05:59 PM   #3
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Well, you said yourself that it needs O2 to oxidize the HC and CO. Where do you think the HC and CO go without that process? CO goed out the tailpipe I suppose, and HC builds up on the catalyst. Eventually it gets clogged, right?
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Old 06-21-04, 06:08 PM   #4
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There's no reason why the hydrocarbons wouldn't go out with everything else. It's the hydrocarbons that make the uncatylized rotary exhaust so damn stinky.

You need alot of heat for carbon to build up. That's why it builds in the combustion chamber instead of somewhere in the intake.
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Old 06-26-04, 02:11 AM   #5
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how else do you think it stays cool other than air under it?
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Old 06-26-04, 04:23 PM   #6
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Quote:
Originally posted by mazdaverx713b
how else do you think it stays cool other than air under it?
Huh? The air injected by the air pump is meant for oxidation, it INCREASES the temperature within the cat. It's not a cooling system.
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Old 06-26-04, 04:52 PM   #7
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Carbon DOES buildup in the cat if you disconnect the airpump. When I bought my car the previous owner had the airpump tube disconnected. The car didn't run. What was the problem? The cat was so damn clogged with carbon that the exhaust gasses couldn't even get through anymore. I hollowed out the cat and the car ran great.
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Old 06-26-04, 04:56 PM   #8
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By the time the air reaches that Cat, it would be nearly 150 degrees. The acv itself would get to that temp or more. This itself would progress the longer its ran and would be nearly the temp of the cat itself (which would be really hot do to eaxust gas). The only thing that the pump is going to do is suply with mostly oxygen and some gas fumes possibly do to its fed from the air cleaner. There would be no way to "cool" the cat enough to make any differece, except mabye water, which cools the best on contact.
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Old 06-28-04, 02:23 PM   #9
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what if you take your cat off? It is possible it will clog anything inbetween the muffler and header?
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Old 06-28-04, 02:36 PM   #10
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Nah.
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Old 07-01-04, 10:02 AM   #11
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how exactly do you "hollow out a cat"?? (catalytic converter, that is.... I can see a bunch of "cat" jokes comin' on....
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Old 07-01-04, 10:06 AM   #12
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1) Insert broom stick
2) beat like hell.
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Old 07-01-04, 04:41 PM   #13
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So it looks like no one has actually "burned out" a cat by removing the air pump.
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Old 07-01-04, 05:24 PM   #14
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No need to hallow out the cat, just buy a pre-silencer...
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