O2 location on OBDII mid-pipe for 95M3

[m3f_aeronaut]

Is the O2 sensor heat or flow sensitive? I'm putting a OBDII midpipe on a 95. I marked the location that put the sensor out of the way yet easy to replace, but it's quite a bit closer to the header than the stock 95 mid pipe.



OBDII mid-pipe, marked for O2 bung and install on 95.





OBDI mid-pipe.

[m3f_enderw88]

That location should be fine as long as it really clears the transmission under loads. The only real problem is that you are only sensing from one pipe. The original location is after the collector so it is seeing exhaust from all cylinders.

[m3f_aeronaut]

Understood. Common hearsay is that reading only 3 cylinders is no issue on OBDI.

[m3f_climax_mr2_e36]

Let me know if you need o2 sensors. I have them for a 96m3 and a 99 m3. Not sure if the 96s would work on the 95, but if one of these has the part number that you need, then i could sell it to you for a better price than you would get it elsewhere. Shoot me an email if you want em.

[m3f_Richardsperry]

I put mine just in front of the inboard cat.. (almost where the original would be.)

[m3f_enderw88]

Understood. Common hearsay is that reading only 3 cylinders is no issue on OBDI.

It shouldn't be a problem.

[m3f_aeronaut]

I put mine just in front of the inboard cat.. (almost where the original would be.)

Thanks, I'll crawl back under the car and see what that looks like.

[m3f_das borgen]

OP, sorry to revive a thread but can you please lemme know approximately the location of your o2 on the midpipe measured from the header flange and also at what angle relative to vertical plane (front-back)?


I'm doing this soon

Thanks

[m3f_aeronaut]

I'll get you some measurements and pics soon. Is this weekend too late?

[m3f_Richardsperry]

It really doesn't matter where you put the O2 sensor, as long as it's in front of any cat. Wideband sensors don't like to be too close to the head, (no less than 18"), narrow band not so much.



As to positioning, the sensor needs to be within aprox 20 degs of vertical. (helps keep condensation off the sensor.

[m3f_das borgen]

I'll get you some measurements and pics soon. Is this weekend too late?

Nope, not too late at all.


I'm not gonna drive her for another couple of months easily due to snow, salt, etc. But I wanna get it to a welder as soon as I can find the info.


Thanks a ton


And Richard, my main concern is clearance to other components, not so much performance since I already know what to expect, as you describe.

[m3f_aeronaut]

Here we go.....



From the location on the original 95 midpipe:





I decided to put the O2 sensor in this area on the 96+ midpipe (note red circle, NOT white markings):





From this pic you get a good idea where it's located in a small section of the midpipe:





And this shot represents the angle pretty well. 5 deg or so. The angle is not needed for clearance, but I thought it would help with access to the sensor for removal/install:





There's a lot of clearance around the sensor at this mount point and angle, so you won't have to be exact to fit fine.

[m3f_das borgen]

Perfect sir, thanks a million

[m3f_aeronaut]

Happy to help!

[m3f_Richardsperry]

Yep that's the spot. (RedX)


It won't clear the bottom of the car on the outboard pipe. Says I who has a bung and plug there...Lol (I was inking of putting the wideband there. I didn't check that b4 I welded them both in)