Restoring rear o2 functionality
Thread Starter
Staging Lane
Joined: Nov 2016
Posts: 50
Likes: 0
From: Westminster, MD
Restoring rear o2 functionality Hi all. I just purchased my first LS1 based car, 2000 Trans Am. I unfortunately live in MD so I'm investigating what hoops I have to jump through to restore the car to be able to pass inspections and emissions. Right now the car has long tubes, ORX, and mufflers dumped before the axle. My game plan is probably going to be scrapping the entire exhaust system and rebuilding from the ground up with emissions friendly parts, or just try and find used OEM manifold and cats, and then bolt up a cheap cat back that I found locally. The real shitty part about this whole process is I need to be able to hook all the emissions equipment back up (no emissions bung on headers and no cats), and not owning a LS1 before or knowing one to reference leaves me with a lot of questions.
Right now the car has the rear o2 sensors missing and tuned out (I do not know how). I need to restore their functionality IF they definitely are required to be activated during emissions testing. Any possibility I could pass emissions with these disabled? Inspection only visually verifies that they are present and connected. If I buy o2 sensors and plug them in, will this activate a code? Also if I need to completely reactivate the system, how would I go about doing this? I also need to restore the AIR system. Were there any computer changes that would have been needed to have been made during the removal? With the reactivation of this equipment, would it be easier for me to try and find someone with a tuner to restore everything, or would picking up a factory PCM on ebay for an easier solution?
Right now the car has the rear o2 sensors missing and tuned out (I do not know how). I need to restore their functionality IF they definitely are required to be activated during emissions testing. Any possibility I could pass emissions with these disabled? Inspection only visually verifies that they are present and connected. If I buy o2 sensors and plug them in, will this activate a code? Also if I need to completely reactivate the system, how would I go about doing this? I also need to restore the AIR system. Were there any computer changes that would have been needed to have been made during the removal? With the reactivation of this equipment, would it be easier for me to try and find someone with a tuner to restore everything, or would picking up a factory PCM on ebay for an easier solution?
the only thing the rear O2's do is measure emissions after the cats to determine if the cats are working properly. thats why they can be tuned out without a problem. You might possibly be able to just add aftermarket cats to your Y pipe but it would suck to buy them and have someone say no to it. going to have to do some research. Find a shop that does tunes in your state and ask them what you will need to do
Thread Starter
Staging Lane
Joined: Nov 2016
Posts: 50
Likes: 0
From: Westminster, MD
I was debating buying one of the two of these:
https://www.texas-speed.com/p-2703-s...t-headers.aspx
or
https://www.texas-speed.com/p-292-te...ed-y-pipe.aspx
Unfortunately the second cheaper option has the disclaimer that the cats are not designed to meet emissions requirements. The first option says that it will only work with shorty or factory manifolds. If I end up getting OEM manifolds I might as well just try and track down the OEM piping with cats and just throw on the cat back to finish it. I don't necessarily want to add cats to the X pipe on the car right now. The car is lowered and the 3" X has about 2" of clearance. I want to downsize to 2.5", convert to Y pipe since the X is under the frame, and raise the car back up to gain my ground clearance.
https://www.texas-speed.com/p-2703-s...t-headers.aspx
or
https://www.texas-speed.com/p-292-te...ed-y-pipe.aspx
Unfortunately the second cheaper option has the disclaimer that the cats are not designed to meet emissions requirements. The first option says that it will only work with shorty or factory manifolds. If I end up getting OEM manifolds I might as well just try and track down the OEM piping with cats and just throw on the cat back to finish it. I don't necessarily want to add cats to the X pipe on the car right now. The car is lowered and the 3" X has about 2" of clearance. I want to downsize to 2.5", convert to Y pipe since the X is under the frame, and raise the car back up to gain my ground clearance.
TECH Senior Member
Joined: Jan 2004
Posts: 5,798
Likes: 16
From: St.Charles MO
Before you go through all this trouble you need to find out what your state (or local shop) will allow.
Some states or shops are fine with LT headers and cats as long as the car isn't throwing any codes (check engine light). Some places that are supposed to do a visual inspection just check if your car isn't throwing codes and don't bother checking the exhaust.
For example my state is supposed to do a visual check and check for codes, most of the places Ive been just check for codes and ignore the exhaust as long as there is no codes being thrown, and my car is cammed, LT headers, and no cats (just installed high flow cats though because I was sick of the fuel smell).
I have the stock rear 02 sensors connected to the y-pipe but the wires are not plugged in (just tucked up) and they are tuned out. Never had a problem.
One more thing you can do is wrap the exhaust to have it look like you have cats, if the shop checks they will more than likely not want to go through the trouble of unwrapping the exhaust to check for cats and just assume they are there.
And another option if you don't want to buy cats is to buy fake ones:
http://www.siliconeintakes.com/dsm-i...ter-p-320.html
Not sure if you care but installing stock exhaust manifolds and stock Y-pipe will not only be a total pain in the *** but make a very noticeable difference in losing power, sound and throttle response, like 30+ rwhp. You will likely not be happy with he difference if you have to pay money to basically hurt your cars performance. If you bought your car in state talk to the original owner and find out how he passed or where he went to.
Some states or shops are fine with LT headers and cats as long as the car isn't throwing any codes (check engine light). Some places that are supposed to do a visual inspection just check if your car isn't throwing codes and don't bother checking the exhaust.
For example my state is supposed to do a visual check and check for codes, most of the places Ive been just check for codes and ignore the exhaust as long as there is no codes being thrown, and my car is cammed, LT headers, and no cats (just installed high flow cats though because I was sick of the fuel smell).
I have the stock rear 02 sensors connected to the y-pipe but the wires are not plugged in (just tucked up) and they are tuned out. Never had a problem.
One more thing you can do is wrap the exhaust to have it look like you have cats, if the shop checks they will more than likely not want to go through the trouble of unwrapping the exhaust to check for cats and just assume they are there.
And another option if you don't want to buy cats is to buy fake ones:
http://www.siliconeintakes.com/dsm-i...ter-p-320.html
Not sure if you care but installing stock exhaust manifolds and stock Y-pipe will not only be a total pain in the *** but make a very noticeable difference in losing power, sound and throttle response, like 30+ rwhp. You will likely not be happy with he difference if you have to pay money to basically hurt your cars performance. If you bought your car in state talk to the original owner and find out how he passed or where he went to.
What part of MD are you in? I'm in Silver Spring. I'm going to replace my stock exhaust with LT's, cats and y pipe. The LT's have an O2 bung, and I've bought 3" SS cats that have an O2 bung as well. I've been told that the rear O2 sensors will not work that far down the line, but will see. Have been hesitating starting this project though and am most concerned about getting the old header bolts out.
Thread Starter
Staging Lane
Joined: Nov 2016
Posts: 50
Likes: 0
From: Westminster, MD
What part of MD are you in? I'm in Silver Spring. I'm going to replace my stock exhaust with LT's, cats and y pipe. The LT's have an O2 bung, and I've bought 3" SS cats that have an O2 bung as well. I've been told that the rear O2 sensors will not work that far down the line, but will see. Have been hesitating starting this project though and am most concerned about getting the old header bolts out.
TECH Regular
Joined: Apr 2015
Posts: 423
Likes: 2
From: Rochester, NY
I think your over thinking this. Unless your area does a sniffer test (such as in CA and NY city), modding our cars isn't too difficult and by able to pass inspections.
I'm in upstate NY (not the city), and here they only need to do a visual inspection & ODB scan for codes.
The ODB scan is easy, HP Tuners or other software can tune any codes to not throw an error & pass. I have tuned out my rear O2's and AIR.
The visual scan, unless the garage is a die-hard shop they should only care and look for cats and exhaust system. I use LT with CATS (if you go race style w/o cats, well than that's what you bought "Race only". I plug my rear o2 bungs, but it will be super easy to install old non functioning O2's if the garage really wanted to see them. AIR and EGR, they don't bother or care, for some model years don't even offer EGR (such as the 2001, 2002 years).
Hope this helps at least some.
I'm in upstate NY (not the city), and here they only need to do a visual inspection & ODB scan for codes.
The ODB scan is easy, HP Tuners or other software can tune any codes to not throw an error & pass. I have tuned out my rear O2's and AIR.
The visual scan, unless the garage is a die-hard shop they should only care and look for cats and exhaust system. I use LT with CATS (if you go race style w/o cats, well than that's what you bought "Race only". I plug my rear o2 bungs, but it will be super easy to install old non functioning O2's if the garage really wanted to see them. AIR and EGR, they don't bother or care, for some model years don't even offer EGR (such as the 2001, 2002 years).
Hope this helps at least some.
Trending Topics
Thread Starter
Staging Lane
Joined: Nov 2016
Posts: 50
Likes: 0
From: Westminster, MD
The thing that I haven't gotten an exact answer on is how the tuners turn off these codes. Do they disable the EGR and AIR systems completely, or are they turned on but spoofed to be working correctly. From my researching the emissions testing equipment check for "ready codes". If these systems are disabled then these ready codes will flag their equipment. If they're spoofed to be working then awesome.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo I'm in Westminster so not too far. I bought the car as is with race headers on it, ORX, bullet mufflers with dumps. I just purchased Pacesetter long tubes with the air and egr bungs and the Texas Speed catted Y. The downstream o2's aren't that critical. You may be completely fine and if not you can always buy defoulers to plug them into to trick them into working. Wouldn't happen to have any of the EGR or the AIR system lying around would you? I'll also be selling these non emission compliant long tubes once I pull them off and replace them if you're looking for something cheaper. Not even sure of the make right now. PM me if you're interested so this thread can stay on topic.
TECH Regular
Joined: Apr 2015
Posts: 423
Likes: 2
From: Rochester, NY
The thing that I haven't gotten an exact answer on is how the tuners turn off these codes. Do they disable the EGR and AIR systems completely, or are they turned on but spoofed to be working correctly. From my researching the emissions testing equipment check for "ready codes". If these systems are disabled then these ready codes will flag their equipment. If they're spoofed to be working then awesome.
For emission checks you would not want to disable it, instead change the Error Mode to "No Error Reported" & keep the SES light Enabled option checked (HP tuners, I'm unsure of the language for other software).
This allows those codes the function, but never report an error.
Thread Starter
Staging Lane
Joined: Nov 2016
Posts: 50
Likes: 0
From: Westminster, MD
There are a few options to tune the codes.
For emission checks you would not want to disable it, instead change the Error Mode to "No Error Reported" & keep the SES light Enabled option checked (HP tuners, I'm unsure of the language for other software).
This allows those codes the function, but never report an error.
For emission checks you would not want to disable it, instead change the Error Mode to "No Error Reported" & keep the SES light Enabled option checked (HP tuners, I'm unsure of the language for other software).
This allows those codes the function, but never report an error.
