Resolved Front O2 Sensor Location.

[wing3r09]

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  Hey guys, Made a custom down-pipe to fit my HX35 3" V-band, and now coming to the problem of where to weld a bung for the front O2 sensor. The stock location is right off of the turbo, and not sure if I should put it back near the turbo, or move it farther down the pipe.
  
  The reason I would rather move it down is for looks, and not have a sensor out of my beautiful new down-pipe, but I also want it to run and log correctly.
  
  My A/F sensor is going to be right before the Flex pipe and i was thinking of putting the O2 sensor right next to it(closer to the flex pipe). I have an existing bung after the flex pipe where the A/F use to be but decided to move the A/F closer, could this be a possible spot for the front O2 or is this to far from the turbo.

 

[dexterholland04]

As long as there are no exhaust leaks before the sensor, it doesn't matter where you put it in the exhaust.

 

[wing3r09]

Would it matter before or after the flex section?

 

[Nate355RS]

That's true as far wideband reading accurately, but the further down the exhaust stream the o2 sensor is the more lag you'll have in the AFR readings. It just takes a little more time for the exhaust to hit the sensor. For me I'd like to have the sensor as close to the manifold as possible, especially for narrowband use when exhaust gasses are traveling their slowest.

 

[edged1g]

As long as there are no exhaust leaks before the sensor, it doesn't matter where you put it in the exhaust.

True as far as accuracy, but not as far as timing of the response to mixture changes. From the ECMLink Wiki:

There are a number of situations where you may find it easier to install the WBO2 further downstream (in the rearO2 location on a 2G, for example). The problem is that the sensor responds more slowly to ECU mixture changes the further away from the engine it's placed. As a result, the ECU makes adjustments to the A/F mixture too quickly and “overshoots”, running really lean for a few seconds, then really rich, then lean, etc. To correct for this, you need to change how the ECU adjusts the short term fuel trim

Source: Here

 

[wing3r09]

Edged,

That is for wide band, my post is towards the oem front 02 sensor.

I am assuming they are the same as in timing, and you want the oem sensor to read as quick as it can. The oem location (O2 housing) is right after the turbo. I am going to replicate this in my custom down pipe and get it close to the turbine housing.

 

[edged1g]

Edged,

That is for wide band, my post is towards the oem front 02 sensor.

Yes and no. That is for a wideband being used for narrow band simulation, which in effect, is a narrow band.

Basically, the same rules apply. If the narrow band is too far down stream then the ECU will have a delayed response when adjusting the fuel trims. I would put the sensor as close to the factory location as possible.

 

[tmoney20g]

Another option is, if you have ecmlink or whatever, put the wideband per instructions (Innovate recommends 24" post-turbo) and simulate narrowband with link.

In my 1g, I'll ONLY have the wideband, and I plugged the factory o2 location and removed the o2 wiring from the ecu harness, will weld the bung in probably just before my downpipe flex section, and be able to log wideband thru the ecu on the factory o2 sensor data input pin, while letting link simulate narrowband from that.

 

[wing3r09]

If the narrow band is too far down stream then the ECU will have a delayed response when adjusting the fuel trims. I would put the sensor as close to the factory location as possible.

Answers my question.

This is where I will have the stock o2 sensor welded on custom down-pipe.

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