Emissions Testing

[Vostok]

So from what I can gather pretty much every aftermarket tune available for our cars comes with the feature to disable the second set of oxygen sensor monitors.

New emissions laws require that the second set be active in order to pass. I failed today due system monitor items being "not supported" in almost every category.

I do not own a handheld tuner personally so I do not have the privilege of flashing a stock tune every time I need to pass the test.

From a performance standpoint, what does disabling the second set do exactly?

I'm hoping that the gains are negligible and that I can just leave the second set on all the time. Obviously saving time and money on not having to ever replace a set of sensors is a gain but is there anything other than this factor involved?

[EMAS]

From a performance stand point just turning off the rear o2 sensors by itself does nothing to change the performance. However turning off the sensors is usually done when all of the cats are removed. The rear sensors are only present to check if the cats are working as they should. If the car does not have the front cats turning on the rear o2 sensors will still result in the car failing because they will activate a code that indicates that the cats are not working as they should.

[Vostok]

So essentially, the tuners drop the second set basically....just because they could (legally)? Which is no longer the case...

[TAKEDOWN]

This is not good

[Vostok]

This is not good

Nope. I thought the EPA was laying off a little bit but seems to be quite the opposite. :shake:

[TAKEDOWN]

I've got stainless steel works full set up, I'm not sure what's gonna happen now. You are the second member I've heard have the same problem in our area.

[justbob]

Third. I have zero monitors turned on. It gets worse, they do in fact consider transmission codes as emissions related due to the fact if it isn't shifting right, it will make your engine work harder.

I have eight trans codes that have been turned off AND a removed blinking OD light because my tuner couldn't get the car to go into open loop on the dyno.

I have had enough. Between emissions, owning it for 9 years, and every single thing costs $1,000 plus it seems, I will probably drive it till the end of October, let IL take my plates and off load the car next spring in favor of a muscle car to drive and a long term project '29 Ford rat tudor. This car has been nothing but in my way of my true passion of design and fabrication of old iron. "Only so much money to go around..."


Self proclaimed Builder Of Badassery.

Buy it, Break it, Build it BETTER.
"Since 2004"

[james005]

Don't know if they will work but was thinking of putting these on when I start actually upgrading my 03.

http://www.latemodelrestoration.com/item/SVE-MILO2/1996-04-Mustang-SVE-Mil-Eliminators-O2-Sensor-Simulators

[RacerX]

You DO NOT NEED the second set of cats to pass an actual emissions test! You DO need to have all O2s turned on in the tune! This is a fact! Exhaust leaves the engine, is checked by first set of O2s Pre-1st Cat, then hits the second set of O2s PRE-2nd CAT! There is NO O2 sensor after the second cat, hence no measurement taking place after that cat!!!

[nh muscle]

Why does your tune have everything off? Thats a little messed up. I would call martyo or lideo and tell them what you need to pass or you could just return to stock and let it go ready then get your sticker and return to full fun!

[RacerX]

Turning off the rear O2s prevents the PCM from monitoring the cats and the O2 heaters/monitors from turning on. Depending on the tune, if you have all O2s turned on and the PCM sees the cats getting too hot, it will richen up the mixture no matter what you're commanding to cool the cats so you don't destroy them. That's why it's just easier to turn them off. With the stricter emissions testing coming out in more states, these simply need to be turned on and whomever wrote your tune in the first place should be able to take care of it for you no problem.

[nh muscle]

Yes what bill said. he has a black marauder. They have more problems going ready and passing emmissios testing!

[lji372]

Borrow a buddies stock car and switch the dash and plate, tell them the PCM is out of a bone yard if they mention an unmatching vin # in the PCM:dunno:

[Vostok]

I already have a plan in motion, it will be taken care of and I will pass eventually. I was just trying to establish if the rear o2's activity have any affect on performance. So far from all the information I've gathered there is none, other than politics and possibility of a check engine light coming on intermittently for rich condition?