Emissions Question

[96Camaro]

How would I go about taking off all of the emissions things on my car like the cat and whatever those things are called hooked up to the headers . I am thinking there is some things I would need to block off and all of that. But I'm sure some of you guys have done it before so any help is appreciated. Hope I stated my question clearly enough.

[N20LT4Bird]

Why do you want to remove emissions? This will most likely devalue your car as no one will want to purchase it in a state where emissions laws are present......not to mention its illegal in any state and there really is little power gain from it.

However, if youre just asking for the sake of asking.......if you were to remove the convertors from your car, you will need to omit the rear O2 sensors from the computer program....or buy simulators. The PCM will pick up the inefficiency of the cats (or lack there of) and trip an SES light on the dash.

The other emissions equipment is the AIR system and the EGR. The AIR can be removed by disconnecting the aspirator tubes in the headers and removing the pump on the front of the motor. The holes in the headers will need to be plugged with a fitting. The EGR can be removed by removing the valve, tubes and fittings and bolting a block off plate on the manifold. This will also trip an SES light.


I wish the previous owner of my car left it all in place because the emissions laws have just come to be in upstate NY and I am going to have a hard time in a couple of months when i go to inspect it....so dont do it. It doesnt make any sense and its really a woodchuck move.

[Injuneer]

I'll cast another vote for leaving the emissions alone. There is no power gain from removing the EGR, AIR or EEC systems. The gain from removing the cats is negligible. All you will do is reduce the weight of the car a bit, and in the case of the AIR, reduce a small amount of clutter. You will also create a bunch of problems with SES lights that will need corrections. And, a system like EGR can actually provide benefits other than reduced emissions, including reducing the potential for detonation (knock) under sertain conditions. Removing the PCV system components can actually damage your engine.

I built an 800HP nitrous stroker, and kept 100% of the emission equipment intact, and functional. It didn't cost me any measureable HP at all. Only when I retired the car from the public streets and turned it into a "track only" car did the emissions come off.

[96Camaro]

Well what I really wanted to know this for is because if I were to get headers that dont come with the emissions hook up deal. And I'm not sure if taking off the cat will help much or not. But thanks for the input, would like to hear more from you guys on this.

[Injuneer]

When you say you are "taking off all of the emissions things on my car ", its a bit too general. If what you really mean is how do you work with "non-emissions" headers, its a different story. First, the Hooker Super-Comp lomg tubes don't even have the bungs for the O2 sensors, so you need to make sure that's not what you are talking about. Or if you are going for Hookers, you will need to make sure they have the O2 bungs added to the collectors BEFORE the headers are coated (if you're gettingthem coated). Most other brands have at least the O2 sensor bungs, and many of them offer an option for both EGR and AIR.

So.... all you are really talking about, assuming your headers have no connections for the EGR riser tube and the two AIR injection ports, is removing EGR and AIR. You will need block-off plates for the holes on the rear of the intake manifold that the EGR valve and the riser tube bolt to. You can get those plates from SJM Manufacturing. Then when you remove the EGR solenoid and the vacuum lines, you'll need a small vacuum cap for the nipple on the driver's side of the intake manifold. And, you oeither need to build an EGR "simulator" circuit to fool the OBD-II PCM into thinking the system is still there (actually, to do the simulator, you need the solenoid left in place), or you need to have the EGR diagnostics turned off in the PCM. If you have an sort of emissions testing where they plug into the ALDL connector, you will be in trouble, because "programming out" the EGR diagnostics results in the system showing up as "not ready" when they do the emissions scan.... a couple of those and you fail.

On the AIR, pull the air supply hose off the intake ducting and cap the connection with a 5/8" vacuum cap. Unplug the AIR pump and unbolt it from the front of the engine. Remove all the plumbing, which usually requires cutting the aluminum tube that runs under the timing cover to the passenger side of the engine. Then there are some electronics and vacuum parts that need to be removed (how much depends on whether your car had the AIR pump recall work done). Then there's another vacuum cap for the line running to the driver's side of the intake. And yet another need for a PCM reprogramming to delete the AIR system diagnostics.

To me, it just makes a lot more sense to get headers that have the required emissions connections, and keep all the systems intact.

[96Camaro]

ok well thanks for the help. So you all are basicly saying that getting headers with emissions and the o2 sensor holes are a better idea then to go with headers without those things?

[N20LT4Bird]

ok well thanks for the help. So you all are basicly saying that getting headers with emissions and the o2 sensor holes are a better idea then to go with headers without those things?

yes....

[Injuneer]

ok well thanks for the help. So you all are basicly saying that getting headers with emissions and the o2 sensor holes are a better idea then to go with headers without those things?

I'll try to explain it a little more clearly.... you MUST have O2 sensors, or the complete PCM control system for you car will not work properly.

The PCM needs the feedback from the O2 sensors to maintain the A/F ratio. Without that control, your engine can run rich and foul plugs and give poor gas mileage, or run lean and lose power and detonate.

It is technically possible to force the system to run "open loop" without the O2 sensors, but that is not really practical unless you have frequent access to a dyno for tuning, and plan to recheck the tune every time you make any alteration to the engine.