c5 cat removal??
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,730
Likes: 4
From: Delray Beach Florida
c5 cat removal??
What do i need to do or buy to have the cats removed. i think there is soemthing about the O2 sensors? Obviously i know i need a shop to cut them off, thats the easy part. but what else need to be done. thanks
Drifting
Joined: Sep 2007
Posts: 1,442
Likes: 1
If it is just the pup cats then you don't need to do anything. If you get the main cats cut off then you will either have to get o2 sims or get the o2 stuff programmed out of your computer. I don't know if you can get any o2 sims anymore though.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,730
Likes: 4
From: Delray Beach Florida
As for the pup cats, where are those and where is the main cat? i thought there was only the 2 cats after the manifolds, up under the car
Drifting
Joined: Sep 2007
Posts: 1,442
Likes: 1
I dont know if they were on the 98's or not but they were on my 2001. The pup cats are small cats right off the the exhaust manifolds. The main cats are about a foot or two after the pup cats and are bigger than the pups.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,730
Likes: 4
From: Delray Beach Florida
SOO to get an o2 sim, is hard to find?
Drifting
Joined: Sep 2007
Posts: 1,442
Likes: 1
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,730
Likes: 4
From: Delray Beach Florida
IF i dont get the sims, and i dont get it programed out, what will happen just the check engine light comes on? or will the car run funny?
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Team Owner
Joined: Apr 2001
Posts: 54,204
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From: S.W. Ohio. . . . . . NRA Life Member
now that we know your C5 is a 1998, then there's no need to spend time thinking about pup cats... because it doesn't have them.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Do you have to go through a smog inspection in Houston?? If you do, the chances are that the car won't pass a sniffer test without cats. If TX requires a visual, then that will be a problem. Check the laws first before the torch gets fired up 
Federal law prohibits the removal of working cats, so if you go to a shop and ask them to cut them off, they will most likely say no. The fine, should they get caught is in 5 figures, IIRC around $15K
Even replacing a cat that is working fin with something like a hi-po cat is technically a no-no.
Federal law prohibits the removal of working cats, so if you go to a shop and ask them to cut them off, they will most likely say no. The fine, should they get caught is in 5 figures, IIRC around $15K
Even replacing a cat that is working fin with something like a hi-po cat is technically a no-no.
Thread Starter
Drifting
Joined: Jun 2006
Posts: 1,730
Likes: 4
From: Delray Beach Florida
yes i know the laws
as for Y, my plan is to finish my exhaust. right now i only have cat back. i want to do headers and no cats. so i'm just trying to do alittle preplanning research is all
as for Y, my plan is to finish my exhaust. right now i only have cat back. i want to do headers and no cats. so i'm just trying to do alittle preplanning research is all
Instructor
Joined: Aug 2007
Posts: 155
Likes: 0
From: Bushwood
St. Jude Donor '08
Several issues are referenced here, but I'll take this opportunity to weigh in on something that hasn't been mentioned - noise. All C5 mufflers regardless of factory or aftermarket are tuned for cats. Cat removal and mods make it a bit of a crap shoot as to what the car will sound like. My blown mn6 w/LG Pro LT's, EG Whiplash cam, no cats and Corsa Touring Editions (yes, the quieter of the two) is unbelievably loud! I'll be faced with some tough decisions if replacing my Corsa's w/Ti's doesn't control the problem. Also, don't kid yourself about cat's restriction, and if you are FI, cat problems escalate!
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Tikiman, to answer a couple of your specific questions:
Yes, if you do not have the rear O2 sensors disabled, either by sims or a tuner, the engine will set codes. But they are harmless, and will not affect the performance in any way. The light will just stay on.
However, in Texas, you will fail the smog inspection.
Here, they do not do a sniffer, they simply access the cars computer and check for any issues. Also, they are "supposed" to do a visual check, but very difficult to do on a Vette; I have never had them look under my car.
But, with the O2 code on, that is a dead giveaway to the inspector, so he might look.
O2 sims are getting difficult to get, as stated, none of the vendors advertise them anymore.
But if you are going to get headers, you will need a professional tune, and they can delete the rear O2 signals then.
All they being said, there are a lot of other negtives to running without cats; smell, legalities, unwanted noises.
DG
Yes, if you do not have the rear O2 sensors disabled, either by sims or a tuner, the engine will set codes. But they are harmless, and will not affect the performance in any way. The light will just stay on.
However, in Texas, you will fail the smog inspection.
Here, they do not do a sniffer, they simply access the cars computer and check for any issues. Also, they are "supposed" to do a visual check, but very difficult to do on a Vette; I have never had them look under my car.
But, with the O2 code on, that is a dead giveaway to the inspector, so he might look.
O2 sims are getting difficult to get, as stated, none of the vendors advertise them anymore.
But if you are going to get headers, you will need a professional tune, and they can delete the rear O2 signals then.
All they being said, there are a lot of other negtives to running without cats; smell, legalities, unwanted noises.
DG
Burning Brakes
Joined: Jun 2002
Posts: 1,055
Likes: 0
From: Troy MI
I agree that the exhaust smells. At least on my car with the G5X2 it does. I have no cats on my GTP, but it does not smell like the vette does.
If you are pre-planning the headers, there is really no need to do it until you get the headers.
I took the manifolds off, cut the cats off about 1-2" behind the cats.
I put the headers on, then drove to the exhaust shop. I had a headache after a mile, but it did sound cool...
I just told the exhaust shop to weld up two straight pipes. If the cats are already gone they shouldn't have a problem doing it.
I believe the O2 sims are just a resistor, so you can make them. If you are putting headers on, I would get it tuned anyway. They can delete the code in the tune as others have said.
If you are pre-planning the headers, there is really no need to do it until you get the headers.
I took the manifolds off, cut the cats off about 1-2" behind the cats.
I put the headers on, then drove to the exhaust shop. I had a headache after a mile, but it did sound cool...
I just told the exhaust shop to weld up two straight pipes. If the cats are already gone they shouldn't have a problem doing it.
I believe the O2 sims are just a resistor, so you can make them. If you are putting headers on, I would get it tuned anyway. They can delete the code in the tune as others have said.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Actually, the Sims are a bit more complex; they generate a variable voltage that changes from approx 0.3v to 0.7V every couple of seconds. So, they have a little oscillator circuit apparantly. The computer wants to see a voltage that is changing, and is different from the front sensors. That tells it that the cats are modifying the oxygen content, and are actively affecting the exhaust.
DG
DG
Race Director
Joined: Apr 2007
Posts: 18,048
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From: long Island NY
