Tuning to make stock LT1 pass sniffer w/ no cat
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Joined: Oct 2003
Posts: 149
Tuning to make stock LT1 pass sniffer w/ no cat
Is this possible? I have a stock motor with EGR and AIR with Pacesetter long tubes and offroad Y and I have to pass a sniffer test before this month is up. I could swap the PCM at the gas station right down the street from the station.
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Joined: Nov 2001
Posts: 3,515
From: Kansas
Re: Tuning to make stock LT1 pass sniffer w/ no cat
Im gonna say it depends on where you are located. Some people pass with giant cams and some dont with a stock motor. If you knew some tricks you might be able to get close but its hard on the motor and to be honest Im not sure if even that could get you to pass. Most people who have to pass a sniffer leave on their cats...
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Joined: Oct 2003
Posts: 149
Re: Tuning to make stock LT1 pass sniffer w/ no cat
Hmmm thats a good idea. I just picked up a Borla cat back and I guess I could just put it on and then take off the right side tip and put one of the plates there in place of it 
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Joined: Aug 2000
Posts: 4,305
From: North Vancouver, BC
Re: Tuning to make stock LT1 pass sniffer w/ no cat
You can not pass the IM240 sniffer with an open cutout I don't think, they put these big pipes over your pipes and they have massive suction, plus there is a fan up front, anything that comes out before the exhaust tips will get sucked in LOL
The cat makes a lot of difference so I don't know how it would be to pass without cats, but you essentially make the fuel mixture as good as you can or a bit leaner, with a normal sized cam just let the o2's do their job and raise the idle, then take out timing, more timing = more HC, you take out timing to let the exhaust burn in the headers and heat up the exhaust.
The cat makes a lot of difference so I don't know how it would be to pass without cats, but you essentially make the fuel mixture as good as you can or a bit leaner, with a normal sized cam just let the o2's do their job and raise the idle, then take out timing, more timing = more HC, you take out timing to let the exhaust burn in the headers and heat up the exhaust.
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Joined: Mar 2005
Posts: 66
From: St. Peters or Warrensburg, Missouri
Re: Tuning to make stock LT1 pass sniffer w/ no cat
Originally Posted by bunker
You can not pass the IM240 sniffer with an open cutout I don't think, they put these big pipes over your pipes and they have massive suction, plus there is a fan up front, anything that comes out before the exhaust tips will get sucked in LOL
The cat makes a lot of difference so I don't know how it would be to pass without cats, but you essentially make the fuel mixture as good as you can or a bit leaner, with a normal sized cam just let the o2's do their job and raise the idle, then take out timing, more timing = more HC, you take out timing to let the exhaust burn in the headers and heat up the exhaust.
The cat makes a lot of difference so I don't know how it would be to pass without cats, but you essentially make the fuel mixture as good as you can or a bit leaner, with a normal sized cam just let the o2's do their job and raise the idle, then take out timing, more timing = more HC, you take out timing to let the exhaust burn in the headers and heat up the exhaust.
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