Will no CATS on a C5 drastically affect emission readings?
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,300
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From: Mississauga, Ontario Corvettes were built to be driven...not trailered
St Jude Donor '07-'08-'09
Will no CATS on a C5 drastically affect emission readings?
Looking at an off road exhaust system that includes headers and no cats, as this no doubt will offer better breathing over a CAT system. Question is will the no CAT system pass emission standards.
Just interested if anyone is running a no cat system on the street that is still DMV legal with respect to emissions?
TIA...
Just interested if anyone is running a no cat system on the street that is still DMV legal with respect to emissions?
TIA...
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
One word sums it up!!! NO !!!!!!!!! You will NOT pass emissions! You can run a set of high flow cats and pass. The few hp that they will cost you is insignificant over the smell and emissions hastle over running no CATS!
BC
BC
Drifting
Joined: Apr 2004
Posts: 1,530
Likes: 250
From: CT
I believe it's legal in some states taht don't require emissions testing but you would need to check Ontario law.
If they do a tailpipe sniffer test, your toast.
Here in Connecticut they only do an OBD2 download so if you go to the right place (where the inspector won't question the exhaust smell) you can usually get by.
Hope that helps.
If they do a tailpipe sniffer test, your toast.
Here in Connecticut they only do an OBD2 download so if you go to the right place (where the inspector won't question the exhaust smell) you can usually get by.
Hope that helps.
Race Director
Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
No cats = illegal everywhere, period.
But, depending on the type of emissions test/inspection you have, you can still pass.
My state only does the OBDII computer system check, they do not sniff the tailpipe, nor do they visually check for cats or anything. My car flies thru and passes with no cats.
If a sniffer test is involved, there is still chance you could pass it. Yes, people have done it before. This just goes to show how unnecessary cats have become on modern computer-controlled engines, these cars can run clean enough to pass a sniffer even without cats. Imagine that.
If there's any sort of visual inspection, you will obviously fail that, unless you simply gut a set of cats or better yet, run a straight pipe through the cat housing.
But the bottom line is, even if you sneak it through an emissions test, doesn't mean it's legal.
But, depending on the type of emissions test/inspection you have, you can still pass.
My state only does the OBDII computer system check, they do not sniff the tailpipe, nor do they visually check for cats or anything. My car flies thru and passes with no cats.
If a sniffer test is involved, there is still chance you could pass it. Yes, people have done it before. This just goes to show how unnecessary cats have become on modern computer-controlled engines, these cars can run clean enough to pass a sniffer even without cats. Imagine that.
If there's any sort of visual inspection, you will obviously fail that, unless you simply gut a set of cats or better yet, run a straight pipe through the cat housing.
But the bottom line is, even if you sneak it through an emissions test, doesn't mean it's legal.
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,300
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From: Mississauga, Ontario Corvettes were built to be driven...not trailered
St Jude Donor '07-'08-'09
Originally Posted by AGVI
Can you fabricate a removable CAT setup?? Just pop 'em back in when you go for testing?
US guys...thanks for the feedback...CATS it is
Pro
Joined: Jul 2005
Posts: 671
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From: Huntsville, Ontario Ontario
Originally Posted by AGVI
Can you fabricate a removable CAT setup?? Just pop 'em back in when you go for testing?
Its a nice ceramic coated system from the headers to muffler hook up as well.
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Originally Posted by Bill Curlee
One word sums it up!!! NO !!!!!!!!! You will NOT pass emissions! You can run a set of high flow cats and pass. The few hp that they will cost you is insignificant over the smell and emissions hastle over running no CATS!
BC
BC
My Z06 has supercharger, bigger injectors, LT headers and no cats and it passed Ca smog testing. It is who tunes your PCM that makes it pass or not.
My tuner had me go for a smog pretest which was tailpipe while in a threadmill. He wanted me to use my PCM scanner and have it in record mode during the test. A pretest is not counted against you if you fail.
I then emailed the scanner recording and the smog test results ( which car failed at that time) which he analyzed
JR then did a custom tune which he emailed me which I flashed in and waited until PCM relearned and then went back to same smog test station and car passed !
As long as the tuner knows what they are doing and what the tailpipe exhaust makeup readings are they can get the engine tuned so that the exhaust makeup is correct without having CATs.
If station of course did a visual then car would fail but how many smog stations jack a car up and even look ?
Le Mans Master
Joined: Oct 2002
Posts: 6,772
Likes: 1
From: Tampa FL
Originally Posted by boosted_z06
Wrong !
My Z06 has supercharger, bigger injectors, LT headers and no cats and it passed Ca smog testing. It is who tunes your PCM that makes it pass or not.
My tuner had me go for a smog pretest which was tailpipe while in a threadmill. He wanted me to use my PCM scanner and have it in record mode during the test. A pretest is not counted against you if you fail.
I then emailed the scanner recording and the smog test results ( which car failed at that time) which he analyzed
JR then did a custom tune which he emailed me which I flashed in and waited until PCM relearned and then went back to same smog test station and car passed !
As long as the tuner knows what they are doing and what the tailpipe exhaust makeup readings are they can get the engine tuned so that the exhaust makeup is correct without having CATs.
If station of course did a visual then car would fail but how many smog stations jack a car up and even look ?
My Z06 has supercharger, bigger injectors, LT headers and no cats and it passed Ca smog testing. It is who tunes your PCM that makes it pass or not.
My tuner had me go for a smog pretest which was tailpipe while in a threadmill. He wanted me to use my PCM scanner and have it in record mode during the test. A pretest is not counted against you if you fail.
I then emailed the scanner recording and the smog test results ( which car failed at that time) which he analyzed
JR then did a custom tune which he emailed me which I flashed in and waited until PCM relearned and then went back to same smog test station and car passed !
As long as the tuner knows what they are doing and what the tailpipe exhaust makeup readings are they can get the engine tuned so that the exhaust makeup is correct without having CATs.
If station of course did a visual then car would fail but how many smog stations jack a car up and even look ?
Race Director
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From: Science Bitch! Mississauga, Ontario
Canadian Events Coordinator
Originally Posted by 4GTABODT
Actually Les, the system I'm looking has that as an option...I was just seeing if I had to go the extra mile to get them but based on the above feedback, it looks like I have no choice...besides, I forgot about the "smell" factor when you don't have CATS... I ran the 86 with no CATS and the odour was quite noticable...not as bad as one of your SBD's but close
US guys...thanks for the feedback...CATS it is
US guys...thanks for the feedback...CATS it is
Thread Starter
Le Mans Master
Joined: Mar 2002
Posts: 5,300
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From: Mississauga, Ontario Corvettes were built to be driven...not trailered
St Jude Donor '07-'08-'09
Originally Posted by AGVI
SBD's?
and his "Silent but deadly" routine...smells a bit like
Pro
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Originally Posted by Neablas
what tuner was that? .. would he do mail in?
He only has the PCM 1 day if you mail it to him but you need to give him a complete list of changes made to car, what smog tests your county does and best case is if you can email him a PCM scanner recording so he knows exactly what changes needs to be special to your car.
I have had 2 friends also with superchargers and in Ca that used JR and their C5s also passed smog without cats.
