Quick exhaust question
Thread Starter
Burning Brakes
Joined: Jul 2011
Posts: 907
Likes: 27
From: The Woodlands TX
Quick exhaust question
Ok, I'm looking at getting a set of LT's with the X-pipe for my 02 Z06. Seeing as the 02 sensors plug in on the headers, before the cats, I am assuming it will throw a code either way, cats or no cats. Meaning the car is going to require a tune to get the engine light off.
So my question is this, If they are going to tune out the check engine light and this is irrelevant to having cats or not, why would you opt for the cats?
Maybe I have just misunderstood it this whole time, but initially I thought the point of having cats was to avoid the check engine light (besides the cleaner emissions of course).
So my question is this, If they are going to tune out the check engine light and this is irrelevant to having cats or not, why would you opt for the cats?
Maybe I have just misunderstood it this whole time, but initially I thought the point of having cats was to avoid the check engine light (besides the cleaner emissions of course).
Pro
Joined: Jan 2010
Posts: 586
Likes: 0
From: Glendale CA
Did you want to get a complete system with the X-pipe? You might have overlooked the after-cat sensor bungs.....there are two pre-cat sensors (like the ones on your headers) and two after the cats.
AGAIN, this is to say the system has cats....off-road systems may be another story.
AGAIN, this is to say the system has cats....off-road systems may be another story.
Thread Starter
Burning Brakes
Joined: Jul 2011
Posts: 907
Likes: 27
From: The Woodlands TX
Did you want to get a complete system with the X-pipe? You might have overlooked the after-cat sensor bungs.....there are two pre-cat sensors (like the ones on your headers) and two after the cats.
AGAIN, this is to say the system has cats....off-road systems may be another story.
AGAIN, this is to say the system has cats....off-road systems may be another story.
Burning Brakes
Joined: Oct 2004
Posts: 931
Likes: 35
From: Rowlett, Texas
Yes, there are 4 O2 sensors; 2 ahead of the cats that read the exhaust and tune the engine, 2 behind the cats that check for cat performance. When you tune out the cat sensors you turn off the rears only, as they have no effect on the engine tuning, they just set a CEL light if they detect poor cat performance.
- You really need a tune to take full advantage of the headers, but the engine will run pretty decently without a tune, just leaves 15 HP or so on the table.
- If you don't use cats, the rear sensors will set the CEL, but it won't affect engine performance in any way, it's just annoying.
- If you use Hi-perf cats, you MAY still set the rear O2 CEL, as the HP cats are not as efficient at cleaning up the exhaust.
So, you can go cats or catless, and the tuner can adjust the system (and tune out the rear sensors) to achieve max performance.
However, most guys on here recommend at least using the hi-flow cats, as they take away negligible HP, add a bit of low-end torque, and smell MUCH better, and they are environmentally and inspection- friendly.
If you just throw on the headers with or w/o cats and don't tune it, it will run okay, it will probably set the rear sensor CEL, and it won't gain very much HP.
DG
- You really need a tune to take full advantage of the headers, but the engine will run pretty decently without a tune, just leaves 15 HP or so on the table.
- If you don't use cats, the rear sensors will set the CEL, but it won't affect engine performance in any way, it's just annoying.
- If you use Hi-perf cats, you MAY still set the rear O2 CEL, as the HP cats are not as efficient at cleaning up the exhaust.
So, you can go cats or catless, and the tuner can adjust the system (and tune out the rear sensors) to achieve max performance.
However, most guys on here recommend at least using the hi-flow cats, as they take away negligible HP, add a bit of low-end torque, and smell MUCH better, and they are environmentally and inspection- friendly.
If you just throw on the headers with or w/o cats and don't tune it, it will run okay, it will probably set the rear sensor CEL, and it won't gain very much HP.
DG
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Pro
Joined: Jan 2010
Posts: 586
Likes: 0
From: Glendale CA
Alrighty.....here it goes....and btw you'll also find alot of info if you search "air tubes" or "O2 sensors" in the C5 section....people have pics too 
The AIR TUBES are small piping that are located on BOTH the driver and passenger side, connected to one of the 4 pipes of the header. these are connected to the matching air-tube piping located again on both sides. NOTE: the 00-04 has a different position for the passenger side air tube than the 97-99...don't as why
FUNCTION OF THE AIR TUBES are just to blow fresh air in the manifolds and HEAT UP THE CATS FASTER (as part of EPA regulations, to get the cats working faster which = less hydrocarbons in air)......hence it has NO OTHER FUNCTION THAN TO QUICK-HEAT YOUR CATS (and make your car sound like a vaccum cleaner on startup
) so I pulled my AIR relay (fusebox next to battery) and blocked off the air tubes on the headers, and just left the car's coming air tubes in place.
Hope this helps
The AIR TUBES are small piping that are located on BOTH the driver and passenger side, connected to one of the 4 pipes of the header. these are connected to the matching air-tube piping located again on both sides. NOTE: the 00-04 has a different position for the passenger side air tube than the 97-99...don't as why
FUNCTION OF THE AIR TUBES are just to blow fresh air in the manifolds and HEAT UP THE CATS FASTER (as part of EPA regulations, to get the cats working faster which = less hydrocarbons in air)......hence it has NO OTHER FUNCTION THAN TO QUICK-HEAT YOUR CATS (and make your car sound like a vaccum cleaner on startup
) so I pulled my AIR relay (fusebox next to battery) and blocked off the air tubes on the headers, and just left the car's coming air tubes in place. Hope this helps
Thread Starter
Burning Brakes
Joined: Jul 2011
Posts: 907
Likes: 27
From: The Woodlands TX
Alrighty.....here it goes....and btw you'll also find alot of info if you search "air tubes" or "O2 sensors" in the C5 section....people have pics too
The AIR TUBES are small piping that are located on BOTH the driver and passenger side, connected to one of the 4 pipes of the header. these are connected to the matching air-tube piping located again on both sides. NOTE: the 00-04 has a different position for the passenger side air tube than the 97-99...don't as why
FUNCTION OF THE AIR TUBES are just to blow fresh air in the manifolds and HEAT UP THE CATS FASTER (as part of EPA regulations, to get the cats working faster which = less hydrocarbons in air)......hence it has NO OTHER FUNCTION THAN TO QUICK-HEAT YOUR CATS (and make your car sound like a vaccum cleaner on startup) so I pulled my AIR relay (fusebox next to battery) and blocked off the air tubes on the headers, and just left the car's coming air tubes in place.
Hope this helps
The AIR TUBES are small piping that are located on BOTH the driver and passenger side, connected to one of the 4 pipes of the header. these are connected to the matching air-tube piping located again on both sides. NOTE: the 00-04 has a different position for the passenger side air tube than the 97-99...don't as why
FUNCTION OF THE AIR TUBES are just to blow fresh air in the manifolds and HEAT UP THE CATS FASTER (as part of EPA regulations, to get the cats working faster which = less hydrocarbons in air)......hence it has NO OTHER FUNCTION THAN TO QUICK-HEAT YOUR CATS (and make your car sound like a vaccum cleaner on startup
) so I pulled my AIR relay (fusebox next to battery) and blocked off the air tubes on the headers, and just left the car's coming air tubes in place. Hope this helps
Pro
Joined: Jan 2010
Posts: 586
Likes: 0
From: Glendale CA