Contour Enthusiasts Group Archives Forums Modifications Duratec Performance Headers vs. Emissions

I am dying to put some headers on, but am worried about emissions test and getting state inspected. I have noticed that a bunch of you have headers... Do you just run outlaw and worry about the ticket when you get one or what?

Thanks

I have them and am not really worried about anyone seeing them. The only time it would be a problem here is during annual vehicle inspection and I am reasonably sure the guys I go to have no idea the car had precats and even if they did you can't see the headers that well. I have never had a police officer even look at the engine in any car I drive so it shouldn't be a problem. As long as you keep the main cat on the car it is still very quite and shouldn't draw any unwanted attention.

thanks for the input
how do the precats work with the headers? my main question is is there any way to pass state inspection with headers?

The precats are gone when you install headers so they don't work. When you have your car inspected do they just visually check it or do you have actual emission testing. Others claim it will pass emission test but I don't know that for sure so I won't say. Even if you can pass emission testing you still are not really legal because you have removed emission equipment.

Thanks. I am pretty sure they actually test the emissions. I will have to find out for sure. How do you like your Borla Cat back. Can you hear the exhaust when your cruising on the highway, compared to the factory svt exhaust.

The Borla is nice, it was quite even with the headers but sounded much better than stock. Since I took off the last cat it is much loader but still sounds good, little to no rasp. I am sure if you installed Borla with precats and main cat still in place it would sound pretty much stock (slightly louder).

I passed the Colorado rolling emissions test with flying colors w/gutted pre-cats and a SHOShop Y-pipe w/hi flow cat. As far as a visual test, there is not much room to see if you have headers when looking from above. From below they can be seen, but they don't really stand out that much like on a Honda or something along those lines. HTH

Alex in Boulder, CO
95SE MTX
157hp 151tq before latest mods...

thanks

I responded to this same question at length receintly and you may find it with a search.

A couple of highlights.

Pre cats are part of the emissions system and tampering or removing is illegal.

OBD II systems (96 and newer) have a cat monitor built into the EEC system and will set the check engine light if the cat is removed or if it is not working well.

The cat monitor only monitors the pre cats on our cars. The readings on a smog test may be clean enough to otherwise pass, but the test would be failed from the CEL.

The CEL can be turned off momentarily by disconnecting the battery or removing the fuses to the EEC momory long enough for the memory to be dumped. It will stay off until the next time the cat monitor runs, which can be as soon as an hour or two of driving or as long as several weeks depending on when conditions are right for the cat monitor to run.

When the monitors have not been completed (there are several, not just the cat monitor) there is a code in the processorer that says it has not completed yet. In the near future, at least in California, if the code showing the monitors have not run is present, a smog test cannot be done.

There are several sources that sell devices that fool the EEC system into believing that the cat is OK. It will keep the monitor from detecting that the cat is not working. This is of course not legal. Another answer is that you can extend the wiring for the rear O2 sensors and mount them behind the main cat, but this isn't really legal either.

The main purpose of the pre cats is to clean up the exhaust more quickly after a cold start. The first two or three minutes are the most critical. They really are not needed much after that, that is why the tailpipe readings may be clean enough without the pre cats. Anyway, it is your choice and your risk.

Can't help you on this one. OK did away with inspections last year. Won't have to worry until EPA mandates emmisions tests or Tulsa goes back on the dreaded "dirty air list". As far as CEL's go, MSDS headers come with mil-eliminators. Have had no cel's since install.