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Author Topic: Why do people delete rear o2 sensor? Just curious...  (Read 9244 times)
royce5950
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« on: August 15, 2016, 02:12:56 AM »

I was thinking about it just now and I figured I'd go ahead and ask. This seems to be the right place to do it. I was wondering why some individuals wish to edit/erase out their rear o2 in tunes? I used a spacer for my rear o2 (right angle bung spacer) and I have never had any codes for not having a rear o2 sensor. I have full turbo back and no cat. My setup is 3" DP, 3" racepipe that tapers down to 2.5", then 2.5" mandrel bent pipe all the way back to a round magnaflow. My racepipe has a threaded bung for the rear o2 sensor and when I bought everything necessary to build my seup (DP, Racepipe, Various t304 mandrel bent tubing... etc) I just purchased a right angle spacer and vcds gives me a pass in regards to my readiness... well I haven't ran a readiness test since I flashed but I think I'm good... Anyways for me personally the right angle adapter has suited me well...

Either that, or do people code it out so that they can remove the rear o2 and replace it with a one-wire o2 sensor that delivers a signal straight to an AFR gauge rather than the ECU? In that case it makes sense.

Just wondering  Smiley
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fknbrkn
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« Reply #1 on: August 15, 2016, 02:48:40 AM »

why some people byuin some kind of "right angle spacer" when its much easier to code out second o2 ?
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royce5950
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« Reply #2 on: August 15, 2016, 03:45:44 AM »

Well that answeres that  Cheesy. People probably buy the spacer before they, or if they ever learn how to properly code it out. fuken thank you!
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adam-
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« Reply #3 on: August 15, 2016, 04:59:25 AM »

Because you got lucky.  Most people get a code.  Not even that, if you remove the rear O2 (because it only monitors the cat), you can remove the sensor and put a wideband in.
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vwaudiguy
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« Reply #4 on: August 15, 2016, 08:37:27 AM »

(because it only monitors the cat)

Not true. There's been much debate on this topic if you search. Proof is in the FR.
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royce5950
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« Reply #5 on: August 15, 2016, 08:39:17 AM »

Yeah the idea of replacing with wideband would be great for a AFR gauge assuming you (figuratively speaking, I know you already have a wideband) already have a wideband for lambda. Well technically you could leave the narrowband if thats what you had and install a wideband for the rear bung, but my first priority would be converting to wideband in the pre cat bung.
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royce5950
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« Reply #6 on: August 15, 2016, 08:45:21 AM »

Its true, I have also read much proving that post cat o2 has responsiblities/duties related to the functions of other parameters within the ECU. Ross-tech refers to the rear o2 acting as a snitch that reports back to the ECU alerting the ECU whther or not a number of processes have been carried out properly in regards to various duties the engine requests to be performed by a handful of components in the engine. Such as oil, temps and more. not just AFR and cat stuff. But I too thought that rear o2 was only a snitch for the health of the cat/the presence of the cat until just recently.
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vwaudiguy
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« Reply #7 on: August 15, 2016, 09:54:10 AM »

Its true, I have also read much proving that post cat o2 has responsiblities/duties related to the functions of other parameters within the ECU.

This is the only part of your last post that is true.
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turboat
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« Reply #8 on: August 15, 2016, 02:29:30 PM »

Not true. There's been much debate on this topic if you search. Proof is in the FR.

Thats interesting to see, I was under the impression it was just for cat diagnostics, but experience with a R32 golf has shown otherwise.
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IamwhoIam
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« Reply #9 on: August 15, 2016, 04:56:26 PM »

The sensor doesn't need to be disabled, removing the sensor in order to not get a cat code is a retarded move.
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Carsinc
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« Reply #10 on: August 15, 2016, 07:49:35 PM »

The rear 02 sensor has many jobs on some cars less on others,
The rear 02 can/does drive fuel trims on many cars this is the main
problem people face when removing them. They can be removed in
all of our cars but there is much more work in some and pretty easy in others.
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royce5950
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« Reply #11 on: August 19, 2016, 06:49:38 AM »

This is the only part of your last post that is true.

I agreed with you?

Anyways this is from ross-tech website

The rear O2 sensor is used mostly to monitor the presence and/or condition of the catalytic convertor, although in some applications it also contributes to trim information. Based on feedback from the snitches (pre-cat sensor, post-cat sensor, MAF and more...), the ECU learns to apply a correction factor to its commands to the fuel injectors. If you know that your employees take longer than the standard allotted time to do a specified job, you will need to adjust for that in your planning (injectors are in a union, so it is tough to fire them). The learned values go between the maps in the ECU's Flash ROM (the "chip") and the signal to the fuel injectors. These learned compensations are known as "trim". So, when you see "trim", it means "compensation".
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Carsinc
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« Reply #12 on: August 19, 2016, 08:27:12 AM »

The sensor doesn't need to be disabled, removing the sensor in order to not get a cat code is a retarded move.

I have had 5 cust in the last 2 years with burnt up thottle drive due to shorted rear 02, that alone
is enough reason for me to want them gone.
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