Hi,

I'm going to build downstream O2 sensor simulator. Does somebody know something about wiring of that sensor ? Socket has four pins. One is for +12V (actually about +14), next one is GND. That two support heater. So I suppose next pair of pins are connected to ECU. I need information which one ECU reads voltage from and what range of voltage ECU expects to get from sensor. Unfortunately my sensor is broken so I can't measure it

Thanks for your help.

 

According to the Chilton's guide, the signal you'll want is off the white wire (the other wire is most likely a ground for the signal). If you're actually measuring something on your car (I haven't tried this BTW, but it's what Chilton's says), use a pin or some flat piece of metal to backprobe the white wire on the O2 sensor connector. Stick the meter's red probe on the backprobe, and touch the black probe to any old ground. You should have a measurement of somewhere between 0mV and 900mV, with 900mV meaning a low oxygen reading. (I really should try this, as my ECU's been throwing codes about a high reading on the rear O2 sensor...)

Just out of curiousity, what exactly are you simulating, and why?
GMT

 

Thanks for info. Actually I'm going to remove my cathalic converter to see if I can get any power gains. Anyway my sensor is broken so I'm gonna to replace it with that simulator even if I decide to leave my cathalic converter on its place.

 

Gotcha. When you said simulation, I was thinking computer or mathematical model or something, and I just couldn't picture what you were trying to do. Instead, it sounds like you're just trying to fake out your ECU with a dummy O2 sensor. I'm not even sure it's necessary. AFAIK, the downstream sensor isn't used at all when calculating the air/fuel mixture. Of course, if you're trying to avoid getting any error codes thrown (and the MIL light coming on), you will have to do something to fake out the ECU, but I don't think it should affect performance.

If you do end up trying to fake out the ECU, I'd go look for a little voltage regulator (that runs on 12V and produces 5V or something), then just use a voltage divider to drop the 5V down to somewhere between 0 and 0.9 V. You could do it off the +12V that's already there, but I'm not sure how stable that is (probably varies between +12V and +14V like you saw), so that's why the regulator is a better solution.

Standard Disclaimer: I sure haven't tried any of this, but it sounds like it should work to me. Ain't my fault if you burn your ECU tho. If you want to be a little safer, add a fuse on the signal going to the ECU. There's probably one there already, but you want one you can replace easily (ie one that's not a surface mount fuse on the ECU mainboard).

As a side note, I'll throw my vote in for not removing the cat. I'm not sure how much you'll get for gains, and it's really bad for the environment.

GMT

 

Ill buy one off ya. The rear O2 must thorw codes because when you remove the cat youll get the 0702/0703 ers.

 

hm.. my 96 max never threw any codes if i removed the cat converter..