wade99z

My car used to have headers, but the prior owner put the stock manifolds and y-pipe back on a couple of years ago because the headers never sealed well. He left the O2 sims on (there are 3 sensors correct?). I noticed the front O2 sims while doing some maintenance and CAGS delete the other night. There appeared to be another sim zipped tied in on the side of the tranny. Is that a third one?

No codes, BUT ... the faq for headers says DON'T use front O2 sims.

I've heard from one source that the O2 sensors are just tattlers, while the FAQ seems to indicate they affect the A/F mixture, which was what I would have guessed.

Which is it? I haven't had this car but a few weeks and am just planning for down the road. I live in Texas, and we have visual/scan emissions.

Thanks!

conan

iTrader: (5)

You should have 4 sensors to before the cats and two after the cats.

BlutVonSchwachen

iTrader: (7)

As stated above, there should be 4. Two of the o2 sensors, are located before the cats, which are known as your pre-cat o2 sensors. These are the ones you never want to through a simulator on. They are there to let the PCM know how well it's controlling your AFR. I never tried simming them, but I dont think it would throw a code right off. Sims make the computer think the o2 voltage is within proper range, thus no reason for it to throw a code. Though overtime the PCM may wise up and notice the o2 reading never changing and then throw a code, but dont quote me on that. If they are simmed, you will want to get them back into the exhaust as soon as possible. The other two o2 sensors are your post cats, these let the PCM know how well the Cats are functioning. They are simmable, and deleteable, but unless you plan on running off-road without cats, there is no reason to take them out. They are there to protect your cats from burning up.

TheBlurLS1

iTrader: (8)

The front O2's are not designed to run within a certain range like the rear O2's. You must NOT put a simulator on those.

The rear O2's only tell the inspection station guys if your cats are working or not, they do nothing to extend their life. The rear O2's have NO say so in how the car runs. If you run aftermarket cats, you will (99% of the time) still need to adress the rear O2 sensor problem as if you didn't have cats at all.

Since they are set to stay within spec between a certain range, there's a 99% chance that the output range of those cats is not going to be within spec, thus setting off the SES light.


As for the sim ziptied to the side of the tranny, he might have already done the CAGS delete. Check out http://www.installuniversity.com/ins...sity/index.htm for some pics. There are a bunch of plugs back there that look about the same (speedometer, reverse lockout, 2-3 lockout (which is the one you need), etc).

BlutVonSchwachen

iTrader: (7)

That wasnt exactly what I inteded to try and get across. I know the voltage from the front 02 sensors have a large range, but what I was thinking is that using sims on the front may not throw a DTC right off the back, and may be able to run before faulting. Not sure exactly, but I didnt mean to suggesting using them on the fronts at all. I apologise if that was what was brought out of my reply.

orangeapeel

iTrader: (18)

You don't want your front O2's in closed loop.

silverlt1ss

02 sims suck

orangeapeel

iTrader: (18)

Correct. And in most cases it is easier just to get a tune and have them deleted permanently.