hollowed cats
Thread Starter
Racer
Joined: Jan 2006
Posts: 479
Likes: 1
From: Cape Coral FL
hollowed cats
hey guys!
last night a buddy and i hollowed my cats out and bolted them back up in with band clamps.
it wasnt a much louder sound and the CEL has yet to come on.. but i also do feel an increased throttle responce.. any idea what the problem is? a leak in the connection maybe?
also im noticing that the tail pipes are extremely warm, i think that is a side effect of the cats being taken off..
thanks for your input guys!
last night a buddy and i hollowed my cats out and bolted them back up in with band clamps.
it wasnt a much louder sound and the CEL has yet to come on.. but i also do feel an increased throttle responce.. any idea what the problem is? a leak in the connection maybe?
also im noticing that the tail pipes are extremely warm, i think that is a side effect of the cats being taken off..
thanks for your input guys!
Thread Starter
Racer
Joined: Jan 2006
Posts: 479
Likes: 1
From: Cape Coral FL
im not sure even if its not for more hp or very little it picks up a little more.. but from what ive read and heard it suppose to sound a lot louder..
i wanted to do it more for the sound..
i wanted to do it more for the sound..
Le Mans Master
Joined: Jan 2001
Posts: 5,785
Likes: 6
From: Lafayette Colorado
Originally Posted by Nulltime
Think its good for something like 5hp? I could be wrong.
Keith
Last edited by kromberg; Oct 27, 2006 at 10:28 AM.
Racer
Joined: Mar 2006
Posts: 464
Likes: 0
From: silverdale washington
change front o2 sensors, hotter than normal tailpipes can be a lean condition and you not gettting a cel show they do not have an accurate reading to begin with. and get sims for the rear they are only like 20 dollars.
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Originally Posted by dwarmenzerk
hey guys!
last night a buddy and i hollowed my cats out and bolted them back up in with band clamps.
it wasnt a much louder sound and the CEL has yet to come on.. but i also do feel an increased throttle responce.. any idea what the problem is? a leak in the connection maybe?
also im noticing that the tail pipes are extremely warm, i think that is a side effect of the cats being taken off..
thanks for your input guys!
last night a buddy and i hollowed my cats out and bolted them back up in with band clamps.
it wasnt a much louder sound and the CEL has yet to come on.. but i also do feel an increased throttle responce.. any idea what the problem is? a leak in the connection maybe?
also im noticing that the tail pipes are extremely warm, i think that is a side effect of the cats being taken off..
thanks for your input guys!
Gutted mine... I wish I did not.. All I got was louder which was what I was looking for..
What I did not want was STINK! My garage smells and my clothes smell of fuel..
Worse in the summer..Trust me.. the CEL WILL come on.. takes some time..
Thread Starter
Racer
Joined: Jan 2006
Posts: 479
Likes: 1
From: Cape Coral FL
Originally Posted by TYSON1997
change front o2 sensors, hotter than normal tailpipes can be a lean condition and you not gettting a cel show they do not have an accurate reading to begin with. and get sims for the rear they are only like 20 dollars.
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Racer
Joined: Mar 2006
Posts: 464
Likes: 0
From: silverdale washington
you can buy sims from any auction site for about $20, the fit any gm car, however they are not plug and play like the good ones, you have to hard wire them in, 3 wires not a big deal at all and not like anybodys gonna see them. If your exhaust really is alot hotter than before, like headers glowing red then you could burn it up.
Burning Brakes
Joined: Sep 2005
Posts: 877
Likes: 0
From: Feasterville PA
Originally Posted by dwarmenzerk
oh no headers wernt glowin or ne thing from what i saw, but i did notice the tail pipes were hot to the touch.. someone said that larger injectors would make the car run less lean
Race Director
Joined: Apr 2001
Posts: 19,329
Likes: 15
From: Saint Augustine, FL
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Drive it a while. It will take some time for the computer to learn the new Air/Fuel ratio. One of two things is going to happen. The computer will adjust to the ideal parameters, or a code is going to be thrown. WOT is probably off also now. You really probably should get it tuned. Also, if you didn't disable the rear O2's, you'll get a code.
I personally would never gut the cats. But that's just me. As chuckster pointed out, the stink can be pretty bad.
I personally would never gut the cats. But that's just me. As chuckster pointed out, the stink can be pretty bad.
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Originally Posted by JR_VETTE
Drive it a while. It will take some time for the computer to learn the new Air/Fuel ratio. One of two things is going to happen. The computer will adjust to the ideal parameters, or a code is going to be thrown. WOT is probably off also now. You really probably should get it tuned. Also, if you didn't disable the rear O2's, you'll get a code.
I personally would never gut the cats. But that's just me. As chuckster pointed out, the stink can be pretty bad.
I personally would never gut the cats. But that's just me. As chuckster pointed out, the stink can be pretty bad.
Minor correction.. Gutting the Cats has nothing to do with the A/F.. There are 2 sets of O2's
the first set right off the exhaust manifold are there to measure A/F and the computer adjusts there..
The 2nd set are located AFTER the cats...and they simply monitor the A/F in regards to emmissions.. too much emission sets a Cel...That is it..The computer could care less what happens...
In fact you can drive around forever with the CeL lit and the worst thing that can happen is you will fail inspection.. if you have that in your state..
Florida does not...
Racer
Joined: Mar 2006
Posts: 464
Likes: 0
From: silverdale washington
correction, If you gut the cats and the exhaust flows better and scavenges better there is going to be more air in the combustion chamber and therefore will require more fuel. It will obviously affect the a/f ratio. Next rear 02 sensors do not monitor emissions. And you wont get a code because of high emissions. The computer uses the rear 02 sensors to verify that there is an oxidation reaction taking place inside the cats, by the lack of oxygen in exhaust after cats. The computer will allow the engine to run lean if it thinks that there is not enough oxygen for oxidation reaction. . hence hotter than normal exhaust. Obviously they did put some thought into this though and there is limitations on what it will allow the a/f to be. You wont be able to seize a motor because of a bad 02 sensor.
Race Director
Joined: Mar 2000
Posts: 17,602
Likes: 20
From: Palm City Florida
Originally Posted by TYSON1997
correction, If you gut the cats and the exhaust flows better and scavenges better there is going to be more air in the combustion chamber and therefore will require more fuel. It will obviously affect the a/f ratio. Next rear 02 sensors do not monitor emissions. And you wont get a code because of high emissions. The computer uses the rear 02 sensors to verify that there is an oxidation reaction taking place inside the cats, by the lack of oxygen in exhaust after cats. The computer will allow the engine to run lean if it thinks that there is not enough oxygen for oxidation reaction. . hence hotter than normal exhaust. Obviously they did put some thought into this though and there is limitations on what it will allow the a/f to be. You wont be able to seize a motor because of a bad 02 sensor.
Flowing better has been a big debate.. 2-5hp.. on 350hp the computer would certainly adjust but would be minimal at best..
And you are correct as far as it not measuring EMMISSIONS specifically.. I realize that but was trying to keep the explanation simple.. The poitn I was trying to make is that the rears have zero to do with the PCM and A/F
Racer
Joined: Jul 2006
Posts: 447
Likes: 0
From: San Jose Ca
Originally Posted by slayer6x6
Thats odd, if anything your exhaust should have been hotter with working cats. A working catalyst generates alot of heat.
Originally Posted by chuckster
Minor correction.. Gutting the Cats has nothing to do with the A/F.. There are 2 sets of O2's
the first set right off the exhaust manifold are there to measure A/F and the computer adjusts there..
The 2nd set are located AFTER the cats...and they simply monitor the A/F in regards to emmissions.. too much emission sets a Cel...That is it..The computer could care less what happens...
In fact you can drive around forever with the CeL lit and the worst thing that can happen is you will fail inspection.. if you have that in your state..
Florida does not...
the first set right off the exhaust manifold are there to measure A/F and the computer adjusts there..
The 2nd set are located AFTER the cats...and they simply monitor the A/F in regards to emmissions.. too much emission sets a Cel...That is it..The computer could care less what happens...
In fact you can drive around forever with the CeL lit and the worst thing that can happen is you will fail inspection.. if you have that in your state..
Florida does not...
Melting Slicks
Joined: Jan 2004
Posts: 3,012
Likes: 15
From: Jensen Beach FL
Originally Posted by chuckster
Gutted mine... I wish I did not.. All I got was louder which was what I was looking for..
What I did not want was STINK! My garage smells and my clothes smell of fuel.. Worse in the summer..
Trust me.. the CEL WILL come on.. takes some time..
What I did not want was STINK! My garage smells and my clothes smell of fuel..
Worse in the summer..Trust me.. the CEL WILL come on.. takes some time..
Racer
Joined: Apr 2005
Posts: 348
Likes: 2
From: Miami Fl
hey dwarmenzerk,i see you're in cape coral,i'm in miami and i can shut down your rear o2's so you don't get a cel light and even lower your fan temps for a 160 thermostat if you haven't done that yet,i can also see if you ecm is pulling timing and do some data log,i have a scanmaster and also hp tuners pro,pm me if interested.