[RESOLVED] Why Eliminate O2 Sensor?

[snowborder714]

I have read about people eliminating the rear O2 sensor (not sure if people eliminate the one on the housing or not). Why do people do this? I know some exhaust systems don't have a bung for it but why do people choose not to weld one on? This is where a wideband O2 sensor would go...do those people just not use one?

I've searched and found a lot of threads about people asking if they can eliminate it, the effects of doing it, or how to trick the ECU to thinking it's still there, but haven't found any info on why it's done.

 

[CanadianTSi]

I would assume most Exhaust Manufacturer's don't weld in the bung to keep costs down therefore most people don't go through the hassle of getting a bung welded in.

Because it affects absolutely nothing most people find it easier to simply leave it out.

 

[snowborder714]

Ok. I can understand the keeping cost down but how does it not affect anything? Doesn't the ECU need to read what that sensor is 'seeing'? Otherwise, why do people get O2 simulators?

Also, don't you need it to pass emissions? I live in a place where that exists, sadly

 

[romeen]

Ok. I can understand the keeping cost down but how does it not affect anything? Doesn't the ECU need to read what that sensor is 'seeing'? Otherwise, why do people get O2 simulators?

The purpose of the rear O2 sensor is to ensure that the catalytic converter is functioning properly. If you remove the CC then the sensor will detect this and cause the CEL to illuminate. Other than that it will not affect the performance of the car. If the CEL is on all of the time you will be unaware if the ECU throws any other codes not too mention that it can be annoying having the light on all of the time. The O2 simulator tricks the ECU into thinking that the sensor is still there and funtioning properly (ie-that there is still a functioning cat in place), hence no CEL.

If you still have your catalytic converter then there is no reason to remove the sensor or use a simulator. Since you have emissions testing I'm assuming you still have your cat.

 

[snowborder714]

I do have to have a cat. Would eliminating it in ANY way (with or without simulator) cause a failure for emissions?

 

[romeen]

I don't know but I don't understand why you would wan't to. My guess is that it probably won't skew the emissions. However, if the inspector visually checks for the presence of your cat they may notice if you have messed around with your sensor.

But again, based on your setup I see no reason why you would want to remove it.

 

[CanadianTSi]

My car Passed Emissions just fine without it.

 

[delta448]

I do have to have a cat. Would eliminating it in ANY way (with or without simulator) cause a failure for emissions?

That depends on how well your car is tuned and what condition the engine is in. Unless, as mentioned, there is a visual inspection. A good tune will pass most emissions tests.

I have heard of people removing the cat and driving a metal pipe through the inlet/outlet with a heavy hammer to remove the inner material. Almost the same effect as removing it. This is kinda illegal though, it shows you knew what you were doing and deliberatly bypassed the converter's function.

 

[snowborder714]

The only reason I'm considering removing it is I would want to swap a test pipe in for track days and such. And (I think) if I put it in, it'll throw a CEL.

My car isn't tuned but the engine's a rebuilt 6 bolt with only 8k miles or so on it. I don't have anything to tune it with right now.

And ya, I've heard about clearing out the cat because the other car I used to drive had that problem (although it cleared itself out which was kind of odd).

 

[oldman]

The only reason I'm considering removing it is I would want to swap a test pipe in for track days and such. And (I think) if I put it in, it'll throw a CEL.

Then swap it out at the track, who cares if you throw a CEL at the track, like already said many times, its only function is to tell the ECU you have a working CAT, absolutely no effects on performance or drivability.

 

[snowborder714]

But if it throws a CEL at the track (guaranteed for swapping out cat for test pipe), how do I know if it doesn't throw it for some other reason?

 

[oldman]

But if it throws a CEL at the track (guaranteed for swapping out cat for test pipe), how do I know if it doesn't throw it for some other reason?

You don't and that's the chance you take unless you have logging capacity. Other than that, just remove it altogether and use a simulator, you can't have the cake and eat it too, a decision has to be made.

 

[snowborder714]

Ok. I figured that was the answer but wanted to ask anyway.