precats and emissions
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Re: precats and emissions (kardashim)
In WI? You'd defnitely pass.
The Precats were put in place to clean up the exhaust while the car is cold and the main cats haven't heated up enough to work well. You should be taking your car through emissions when it is fully warm, so lack of precats wouldn't be an issue.
Furthermore, the emissions testing now (for 96 and later vehicles) is done via the OBDII computer port under your steering wheel, they no longer run it on the dyno or even test the exhaust at all. So basically if the car isn't throwing any codes or warning lights, you should pass. I have no cats at all on my car and it would probably pass emissions here. (I'm not gonna try it though :D )
:cheers:
The Precats were put in place to clean up the exhaust while the car is cold and the main cats haven't heated up enough to work well. You should be taking your car through emissions when it is fully warm, so lack of precats wouldn't be an issue.
Furthermore, the emissions testing now (for 96 and later vehicles) is done via the OBDII computer port under your steering wheel, they no longer run it on the dyno or even test the exhaust at all. So basically if the car isn't throwing any codes or warning lights, you should pass. I have no cats at all on my car and it would probably pass emissions here. (I'm not gonna try it though :D )
:cheers:
Instructor
Joined: Sep 2003
Posts: 147
Likes: 0
From: mission b.c.
Re: precats and emissions (kardashim)
up here on the rainy west coast of British Columbia they scan the obd 2 for codes and also run the car on dyno style rollers from 0 to 55mph to test for emissions. they only test the cars in the Vancouver area. sort of weird logic .it would be the equivalent to testing cars in San Diego area only and not the rest of California.you would probably have to check with the testers in your home area to find out the procedure
Thread Starter
Racer
Joined: Jan 2004
Posts: 395
Likes: 0
Re: precats and emissions (02blueelectron)
they do the obd2 and exhaust here. was just there the other day for my silverado. it failed at 117,000...cat conv bad. nice. they also do a gas cap pressure test as well as the dyno. that's what takes so freakin long. plus the people that work there are over 100 years old
Race Director
Joined: Aug 2002
Posts: 16,730
Likes: 1
From: Redacted
Re: precats and emissions (kardashim)
I swapped on a H-pipe from a 03 Z06, which removes the pre-cats and uses a more efficient freer flowing catalyst. I already had z06 cat-backs installed.
I've compared it with a car with the same setup except gutted pre-cats. The Z06 h-pipe is deeper sounding and has more resonance at 1800 and 2400 rpm than the gutted pre-cats car. There didn't seem to be much difference in the sound between regular C5 with pre-cats and without pre-cats. Just maybe a tiny bit deeper and that's it. The Z06 h-pipe makes a lot more difference for whatever reason.
Supposedly, the 02 and later Z06 cats are a new design that doesn't need the pre-s and works better. Seems to be the ticket. Take off's appear on the used market from time to time.
It's not all that big of a difference.
I've compared it with a car with the same setup except gutted pre-cats. The Z06 h-pipe is deeper sounding and has more resonance at 1800 and 2400 rpm than the gutted pre-cats car. There didn't seem to be much difference in the sound between regular C5 with pre-cats and without pre-cats. Just maybe a tiny bit deeper and that's it. The Z06 h-pipe makes a lot more difference for whatever reason.
Supposedly, the 02 and later Z06 cats are a new design that doesn't need the pre-s and works better. Seems to be the ticket. Take off's appear on the used market from time to time.
It's not all that big of a difference.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
Re: precats and emissions (larrysb)
Precats onyl affect emisions on a cold startup. So a tailpipe test after the car is already warmed up will not fail because of missing pre-cats.
If the emision tester is savy, he may notice missing pre-cats and fail the car; that's why I gutted mine (instead of cutting them completely out).
If the emision tester is savy, he may notice missing pre-cats and fail the car; that's why I gutted mine (instead of cutting them completely out).
