Oxygen sensor bungs - M696

[metroplex]

I noticed that the stock exhaust pipes have smaller bungs upstream of the factory oxygen sensors. Why are these smaller bungs there? Are there wideband O2s that can fit these threads?

[Speeddog]

Those are 'sample' ports used for mixture tuning.

[scaramanga]

what size threads are on these ports? could it be that my arrows sport a .9mm pitch?
I'm wanting to buy an adapter so i can place a temperature sensor in there.

[brad black]

1/8 bsp.

[scaramanga]

I just measured the plug again , it really is a .9mm pitch and not 1/8 bsp.

[Speeddog]

1/8 BSP has 28TPI.

That's 0.907mm pitch, so close you can't tell using a pitch gauge.

And it's 0.383" diameter, which is 9.73mm.

If there were M10x0.9 screws, they'd likely fit.
But I've never seen any, and M10x0.9 isn't on any metric fastener chart I've got.

[scaramanga]

agreed, there are no off the shelf fittings with a .9mm pitch.
I just picked up a 1/8 bspp compression fitting and did some comparing.
but of course before comparing i try'd screwing it in  . it wouldn't go in more than the first thread, if i lubed it and forced it, it would go , but i don't want to do it that way.
original plug = 9.5mm with .9mm pitch
1/8 bspp = 9.8mm with 28tpi
i can see the difference in the pitch. if we cannot find a company that makes them i'll have a couple machined.