Wideband O2 sensor location.. Which would you choose?

[samcat]

Simple question, and having done some digging it looks like a complex subject..

Wideband O2 sensor for my Innovate Motorsport LM-2 (and ultimately EFI).

Not so concerned about location for Innovate testing, as that will be done ad-hock then sensor removed.. But when its EFI this becomes a permanent install.

All of these locations would have the sensor pointing sideways (3oclock position, maybe even 2oclock)





My thoughts:
A
Pros:
[*]Hidden from sight/wandering hands (car is a weekend warrior anyway, so low risk)
[*]Far from tailpipe exit so less likely to get a dodgy reading due to exhaust breathing fresh air in

Cons:
[*]Tight, not even sure if it will fit. To weld it nicely will require removing the header from the engine


B
Pros:
[*]Easy to get to/weld
[*]Far from tailpipe exit so less likely to get a dodgy reading due to exhaust breathing fresh air in

Cons:
[*]Tidy wiring will require some creative thinking. Could potentially fit it on the opposite side.

C
Pros:
[*]Easy to get to/weld
[*]Somewhat hidden, probably as much as A

Cons:
[*]To close to exit? So reading could be affected by fresh air in breathing (there is 18" to the exit from here, including the muffler)



I am leaning towards C, but am concerned about the breathing in fresh air risk..

Thoughts please!

[sideshow]

When the header is brand new and weldable, A is where I would place even it was at 9 o'clock. Now because what you have is no longer virgin metal, anywhere from B & C would be more tempting.

[samcat]

Can always bring it back to Virgin metal.. It's thick and that's just surface rust.

[Clonebug]

15 degrees from vertical and 10 degrees from horizontal is what the interweb says.
I put mine at either 10:00 o'clock or 2 o'clock.

It needs to be high enough to stay out of the condensation during the cold start and warming up the exhaust pipe.

[Steve Arndt]

I choose B. Easy to weld it up since you can pull the muffler and get to it at your leisure.

[MarioVelotta]

I prefer A. It's only one bung and you can put any different muffler on without causing more work later.

[Piledriver]

A, as close to vertical as you can get it, even if you get an extended bung and put it on at an angle leaning forwards.
This will also keep it away from potentially *fatal water splashes.

It will also clear the body done like that.

A Ford 18mm spark plug anti-oiler adapter (or two) might get it done for an extender if you can't find/make one in SS cheap.
Same Ford plug works as a ... plug if/when you remove the sensor.
Never leave the sensor in unpowered.

*fatal for the sensor, anyway, outside doesn't matter, what's going on INSIDE the header is what matters.
I lost a ~year old sensor recently likely due to running E85 and hitting a really cold day.
(LOTS of water happening right after start up, perhaps even some raw fuel)
An extended bung would have likely prevented that.

I'm back to the ~5 year old original sensor I retired and kept for a spare last year
(reads identically AFAICT)

Make absolutely certain the active area of the sensor body under the threads does not contact the hole in the header or it will read rich.
It can get some build up on it which will do the same, so make some extra room.

[samcat]

Well... Its welded. After lots of offering it up, scratching heads and trying to get a good answer without stripped the header from the car it ended up being option D..




The pic makes it look more exposed that it is... Bulk of the sensor is hidden under the exhaust, straight cable run. Have started internal wiring ready for this, probably gonna get it hooked up and tested next weekend.

When the header comes off later this year I will go with adding another bung in position A, as upright as I can get it.. But for now this will do.

[CBDZ]

I've got a similar dilemma. But mine is on a tri-mill off-road exhaust. Do I place the sensor in the collector? On a single cylinder pipe, or elsewhere? I'm worried about it being to close to fresh air if placed on the collector, but also worried about a bad reading if only sampling from one cylinder.