What are you guys WITHOUT a hp tuner or a tune doing to eliminate the rear o2 cel from having no cat? I don't recall any o2 sims for our cars being out. I have in the past used spark plug anti foulers (1-2 of the long ones bored out a little) and inserted the sensor into them to slow down the reading and not set off the light, but it wasn't 100% on every car. Worked perfect on some, and off and on on others. Just want to see what options.

 

I bought a spark plug fouler fix for my catless XTC downpipe, but it didn't fit under the car and i almost ruined the O2 sensor trying to make it fit.

I also bought an $11 MIL fix from ebay for which uses a resistor and capacitor to modify the signal and ground from the o2 sensor, but that didn't work for more than a half an hour.

i was looking at http://www.o2sensorsimulator.com/ as a possible choice before i put my cat back on. I believe actual simulators will work well for the cobalt most of which utilize a 555 timer circuit to replicate the signal of a properly working cat which has a slower waveform. Thats just my opinion though.

 

I think I actually have a 555 timer or 2 laying around somewhere. I never even looked at where the sensor is. No problem welding in a new bung to make it fit though. I'll have to check it out. I already have a pair of them bored out to fit the sensor tip.

Hmm, checked out that link and they're pretty cheap. Instead of wasting my time if the anti fouler won't fit I'll probably just order one of those. If you get one first lemme know how it works.

 

You should be able to use a resistor. I know Lopsidedjester said it didn't work for long, but I've seen them work for years; maybe he just got a bad resistor.

Since the 02 you are needing to simulate was behind the cat, the ECU expects to see a constant reading which lets it know that the cat is working. All you have to do is use the wiring from that sensor and send the ECU the proper voltage and it won't think anything is wrong.

Also, not trying to be rude at all Lopsidedjester, but those "simulators" are simply resistors; the ECU isn't looking for a changing waveform at the secondary 02, only at the upstream sensor.

 

Yeah, but what ohm resistor are we talking? I have tons of them laying around cause I'm always messing around with electronics junk lol.

 

http://zx2racing.com/pages/articles/mileliminators.htm <---- heres a good link on how to make the resistor and capacitor simulator and on what goes on.

it shows that one mega ohm resistor and one micro farad capacitor is needed.

i may have been getting my information mixed up about the sign wave, the wave frequencies are different from the pre-cat and post-cat o2 sensor. I'm not fully sure with or without a working cat if the waveform actually changes for the post-cat sensor, but i do believe that the capacitor is needed on top of the resistor to keep the correct simulated oscillation. Its been a while since i took my circuits analysis class.

 

I'll check out a few things; it's been a while since i've set one up. I just know it's cheaper than buying a premade sim. What you're saying sounds right; I was just saying it does not need to perform crosscounts like the pre cat 02s. I had a friend who would make the setup for me (I verified he used a 555 timer) and then just plug it in.

Edit: http://www.freeinfosociety.com/elect...ew.php?id=2091 : This is a good website. The pictures are clear for the schematic. Just go to an electronics store and you can buy all of this stuff for a little under $5.00 .

 

Thanks guys!