Why won't an O2 sim work on my car?

[Ttop34]

The first one I had on my car gave me a 138 or 183 code which was like high voltage on sensor 1 band 2 or something like that. Why am I getting this? I got my o2 sime from Thunder Racing and I've already switched them out once and how my SES light is on again. I'll take it to Autozone tomorrow but I bet they are going to tell me the same thing again.

Is there anything else I can do? What exactly does the o2 sensor want to read? Less o2's or more? What if I mount my o2 sensor outside the pipe somewhere? What if it's sealed off from all air? Then it would read less o2's right? I really want to fix this problem so I can tell when my car is having a problem and when it's not.

[Backfire]

Mounting an O2 sensor outside the exhaust won't work for a couple of reasons. First, the sensor needs to be hot to work properly. Second, there is a lot more oxygen it the atmosphere than in you exhaust. If you could get it to read outside, the car would think it is running very lean due to the excess O2.

As far as mounting an O2 sim, the location shouldn't make a difference. The sim doesn't "read" anything, it simply sends an oscillation voltage to the computer, right around ideal conditions. The problem might be what computer the sim is calibrated for. I don't know if O2 sensors read differently in different cars, but maybe its not reporting in the proper range for the 3.8 PCM? I am not sure what the correct ranges are, but that is what I would look into.

[Ttop34]

Well I just got it again after I already sent back my o2 sim to ThunderRacing once and got it switched out.

I got the 138 code again. It's a o2 sensor Circut Low Voltage Bank 1 Sensor 2. Why the heck am I getting low voltage with an o2 sim?

By the way, the post cat o2 sensor has nothing to do with performance. It only checks how well your cat is working and if it reads something it doesn't like it sends a SES light.

So what about some how tricking the o2 sensor? Maybe wrap it with something and weld it to the exhaust pipe so that it will get hot and not read any o2's since it's sealed from any air? Heck, we have several technicians here, why haven't we figured a better way to build an o2 sim rather than paying $50 for it.

[RedbirdV6]

Uh the sim does not read anything, it mearly sends one constand electrical signal to the pcm

[Ttop34]

Well I'm talking about putting the old o2 sensor back on and some how tricking it to think that it's reading everything fine, not using the o2 sim.

[strange_trp]

<blockquote>quote:</font><hr>Originally posted by Ttop34:
we have several technicians here, why haven't we figured a better way to build an o2 sim rather than paying $50 for it.<hr></blockquote>

anyone using o2 sims is most likely bypassing the catalytic converter (this is the only thing an o2 sim is good for really). i do not condone this practice and as a professional i will not tell a vehicle owner how to accomplish this task. it's like you asking a doctor the best way to poison someone.

plus, you'll never successfully use a sim in the pre-cat position. signal frequency and amplitude are both out of spec on the low side of pcm parameters.

[ April 15, 2002: Message edited by: strange_trp ]</p>

[Ttop34]

Well what about those who are using high flow cats? Our o2 sensors will still send a SES light so we have to use a o2 sim to keep that off.

I'm not trying to put on on the pre cat sensor, I'm using it for the post cat sensor.

[strange_trp]

using it for post cat sensor and getting codes? hummmm. check continuity of o2 sensor signal wire to pcm with a digital meter. if ok, check for short in this circuit (could be shorting to ground or to b+ from sensor heater circuit).
i don't think you need a post-cat sim for the high flow cats. i thought they were clean enough to pass the catalyst efficiency monitor... try putting the old sensor back in and resetting pcm.

[Ttop34]

Oh wow. Well I'm going to give Matt a hollar some time soon. He has what is now the second fastest N/A V6 Fbody in town(second to me) and is also a EE major. Thanks for the suggestions Strange_trp.

[ucmeflyby]

Here's an interesting article on how to build an MIL/SES eliminator. It's like an O2 sim, but it doesn't take the place of the O2 sensor, just modifies its signal. A lot of the mustang guys running x-pipes use them, worth a try.

http://www.zx2racing.com/mods/mods_mil.htm

[ April 18, 2002: Message edited by: ucmeflyby ]</p>