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View Full Version : What is the sensor after the catalytic converter and is it important??



iwamaryu
05-04-2008, 04:50 AM
My situation is Iíve bought an after market downpipe which fits the oxygen sensor (sensor before the catalytic converter on stock) perfectly but the tread for the second sensor (after the catalytic converter on stock downpipe/c-converter) is incorrect. Iíve read a few treads and Iíve heard that sensor measures the efficiency of the catalytic converter. What it looks like is a long probe (pencil shaped) that goes across the pipe diameter after the stock cat-converter. What Iím wondering is that is this sensor important? as I donít need it anymore since the aftermarket downpipe eliminates the cat-converter (besides I canít insert it into my after market downpipe as the tread hole is wrong).

So what should I do? should I just disconnect it? Or should I connect the sensor and mount it at any misc spot on the chassi, that would mean it will always read VERY Clean exhaust ALL the time (since itís not in the exhaust pipe). What will that do? Will the car/ecu try to compensate somehow due to the abnormally clean exhaust?

iwamaryu
05-04-2008, 05:16 AM
by the way , i have a celica gt4 st185 1990. i forgot this was a all celica site. haha

CPincy
05-04-2008, 05:42 AM
as far as i know that is another oxygen sensor?

iwamaryu
05-04-2008, 05:54 AM
i don't see why there would be 2 consecutive oxygen sensors in the same line of path? it doesn't make sense? or does it? what other cars out there that have 2 oxygen sensors in pretty much the same place?

CPincy
05-04-2008, 06:12 AM
my saturn is setup like that so i just figured its the same on the celica

VikingJZ
05-04-2008, 06:12 AM
My Lexus has two or three O2 sensors (Can't remember how many right now).

Lots of cars have multiple ones, especially performance/sport-tuned engines such as a turbocharged engine.

Slider
05-04-2008, 06:26 AM
i don't see why there would be 2 consecutive oxygen sensors in the same line of path? it doesn't make sense? or does it? what other cars out there that have 2 oxygen sensors in pretty much the same place?

It's just for emissions, it's an o2 sensor. Measures if the cat is working right. Removing it will trigger probably throw a CEL but it shouldn't affect how the car runs since the car uses the first o2 sensor for that.

edit: Mounting it in the open might not work since the o2 sensor works when it's hot enough. You might be able to trick the ECU by wiring in a resistor there's several how to's if you google it. There's even one on how to make an o2 simulator so the ECU just gets a signal that everything is fine but the actual o2 sensor is removed.

iwamaryu
05-08-2008, 06:50 AM
http://i65.photobucket.com/albums/h228/iwamaryu/forum/07-05-08_0107.jpg

Thats the sensor i'm talking about above i'm still not sure what i should do with it. should i just connect it and leave it lying somewhere in the eng bay or should i just disconect it?

raydouble
05-08-2008, 06:59 AM
That is unlike any Toyota O2 sensor I have ever see,

Looks to be a pyrometer for exhaust gas temp. readings, maybe.

alltracman78
05-08-2008, 04:01 PM
That's exactly what it is, a pyrometer.

It's used to measure cat temp. Too much fuel burns up the cat.
It shouldnt' cause any problems if it's disconnected.