Eliminating Catalytic Converters


ColoradoSilverado
09-18-2007, 07:11 PM
Is it possible to eliminate my Converters and just replace them with straight pieces of pipe ? Yes, I know it's illegal but my county doesn't require emission testing.

Bert

knogoodidleft
09-19-2007, 06:10 AM
anything is possible, what year/model, im pretty sure there welded on so you will have to cut them off. If your trying to reduce backpressure and still got the stock manifolds on I would advise you to replace them with some long tube headers.

MT-2500
09-19-2007, 08:24 AM
If 1980 or newer any car that is operated on a federal highway is required to have a cat.

Removing the cat can cause engine running problems.

silverado122775
09-19-2007, 08:49 AM
The newer cars with Comps use the readings from the o2 sensors before and after the cat. you will run into issues

'97ventureowner
09-19-2007, 09:31 AM
Is it possible to eliminate my Converters and just replace them with straight pieces of pipe ? Yes, I know it's illegal but my county doesn't require emission testing.
Bert
If 1980 or newer any car that is operated on a federal highway is required to have a cat.

Removing the cat can cause engine running problems.
MT is correct, while your county may not require emission testing, Federal law prohibits the removal of a catalytic converter, even by yourself. And last time I knew Federal law supersedes all local and state laws. I looked online for the text of the law,( it was the Clean Air Act of 1990) and came across this:http://autoparts.lifetips.com/cat/61691/emissions-control/

vortecman
09-19-2007, 05:28 PM
have any of yall ever been to a tractor pull? to see all the smoke these trucks and tractors are putting up into the air is amazing! how come THAT is legal, but my truck would pollute too much without those cats?

silverado122775
09-19-2007, 06:02 PM
First of all Diesel burn cleaner than Gas.
Second, if everybody took there cat off, then THAT would cause a problem. Society is trying to clean the air, not make it worse

ColoradoSilverado
09-19-2007, 06:32 PM
The only reason I want to take them off is because they rattle like a yar of coins everytime I accelerate. New ones are expensive except the universal ones from Autozone that go for $59 a piece. Anyone ever used these ?
It's a 2000, 5.3
Bert

http://tinypic.com/ei2g51

silverado122775
09-19-2007, 09:44 PM
Those should be fine.. you may only need to replace one of them. I highly doubt both cats are bad.

ColoradoSilverado
09-20-2007, 07:01 AM
Those should be fine.. you may only need to replace one of them. I highly doubt both cats are bad.

No, it's both of them that rattle.

Bert

http://tinypic.com/ei2g51

MT-2500
09-20-2007, 08:15 AM
No, it's both of them that rattle.

Bert

http://tinypic.com/ei2g51

Cats are covered under the 8 year 80k emissions warranty and Calf may be more.
Also some are covered under a recalls.
If both are bad you may have a bad batch.
Call the 800 customer service no in your owners manual.
Good Luck
MT

MT-2500
09-20-2007, 08:26 AM
MT is correct, while your county may not require emission testing, Federal law prohibits the removal of a catalytic converter, even by yourself. And last time I knew Federal law supersedes all local and state laws. I looked online for the text of the law,( it was the Clean Air Act of 1990) and came across this:http://autoparts.lifetips.com/cat/61691/emissions-control/


Here is a couple more links to the epa 1990 clean air stuff.
MT

http://www.epa.gov/air/caa/title2.html#iia

http://www.epa.gov/air/caa/

http://www.epa.gov/air/caa/caa203.txt

http://www.epa.gov/air/caa/caa205.txt

Evansamms
09-20-2007, 08:57 AM
I've got almost an identical truck (2000 5.3, 4x4, longbox, ext cab, (not Z71 though)), my right cat started poppin a code about 1000kms after the replacement limit. I picked up two magnaflow s/steel ones of ebay for 140 delivered. of course i had to take the y-pipe out, and weld them in .. ..but it wasnt that bad. Cheapest i could find cats here (halifax, nova scotia), was 140 each for "whitebox specials". Figured i was better off with the magnaflows.

Evan

vortecman
09-20-2007, 09:14 PM
even highflow cats will make your second o2 sensors send errors, won't they?

dirtdriver11
09-20-2007, 09:21 PM
i was getting the po430 code also, i gutted both cats out and still have the problem. both o2 sensors are new on bank 2

Evansamms
09-21-2007, 06:16 AM
Vortecman, The ones i installed werent the real high-flow ones, like you see, just a round tube. They're a replacement style from magnaflow, (dont remember the model number), they look very similar to the stock ones, a little beefier, and claim to flow some high percentage better. I dont remember exactly which ones they were.. but somethin like this link. And i've not had atrouble code since.. . -8000 kms or so

http://cgi.ebay.ca/MAGNAFLOW-CATALYTIC-CONVERTER-99-03-CHEVY-SILVERADO_W0QQitemZ320155907487QQihZ011QQcategoryZ 33629QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

ColoradoSilverado
09-21-2007, 06:58 AM
i was getting the po430 code also, i gutted both cats out and still have the problem. both o2 sensors are new on bank 2

How did you gutted them out ?

Bert

http://tinypic.com/ei2g51

MT-2500
09-21-2007, 08:55 AM
i was getting the po430 code also, i gutted both cats out and still have the problem. both o2 sensors are new on bank 2

Gutting the cat is the same as removing it.
The cats have to be on and working or you will get or you will always get a 420-430 cat code on later computer systems.
You need to get some cats on it and make sure the engine is running right.
Miss fire or engine not running right will also set a cat code.
MT

dirtdriver11
09-21-2007, 10:54 PM
is there a way to fool the computer system? how does that work with aftermarket exhaust?

MT-2500
09-22-2007, 08:03 AM
is there a way to fool the computer system? how does that work with aftermarket exhaust?

Yes there is.
But may be on the border line of illegal.:grinyes:

Some performance chips use what is called a dummie 02 sensor.

It plugs into the 02 sensor wiring and feeds a dummie signal to the pcm to make it think the cat is working.

But I still say for the best performance you need a cat that has some back pressure control.
Removing all backpressure can cause a engine to lose some power.
MT

silverado122775
09-22-2007, 11:48 AM
that's right.. ever try to blow or suck through a straw that is too big? same princple.. you need some back preasure to allow the air to flow out properly.

NoRiceHere01
09-22-2007, 03:37 PM
its not backpressure thats needed.what is needed is a properly tuned exhaust volume. meaning a tuned pipe length/diameter.this has to do with the pulse of the exhaust exiting the cylinder.the exhaust system is designed so that at low rpm the mixture entering the cylinder is held there by a return pulse of the gases that just exited.removing the pipe or increasing the diamter too much affects this pulse and causes a loss of torque, not necessarily horsepower.at higher rpm you dont want any backpressure because it will prevent spent gasses from exiting properly, thus lowering horsepower.the backpressure of the cats is factored into the design of the exhaust tuning, so yes in a way "backpressure" is needed, but only because of the engines tuning.if the cats are removed and the o2 sensors are simulated, the computer will work right, but low end torque probably wont be what it should.thats why in order to run a straight exhaust system, timing and camshaft tuning really should be changed.however if the cats are in place but gutted, and the sensor simulators stop the computer from showing a trouble code, im sure it will pass inspection.here in new jersey only the computer gets emissions tested, not the actual gasses coming out of the tailpipe like on older cars.this being the case, as long as theres no engine code showing you should have no legal trouble, cause they wont know the cats are empty.im sure your state is the same.sorry to ramble but people ask the catalytic converter question all the time.your question tho is basically will gutting your cats fix your problem and the answer is no.you may not hear the annoying rattle anymore, but the truck wont run right if all you do is remove them

vortecman
09-24-2007, 06:15 PM
i think that ended this thread...

maxwedge
09-24-2007, 06:49 PM
Good post for sure , to add, any alteration to function of the cat is also a Federal offence. Back pressure is also useful during egr operation, if so equipped.

vortecman
09-24-2007, 07:12 PM
why doesn't someone put an end to this argument and DYNO all scenarios (CATS w/ muffler, no cats, no muffler, ..and so forth....)

silverado122775
09-25-2007, 11:06 AM
good idea.. we will wait until you are done with the tests :)

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