O2 Sensor (Oxygen) Mounting Location

[wilbo666]

I've never really had much choice in where to put the oxygen sensor/s in the past, this time however I do!

I wish to mount the factory narrow band sensor and a wideband (Bosch LSU 4.2) sensor...

Wideband:
PLX says 24+ inches (~610cm) (I have a PLX, Page 1)
http://www.plxdevices.com/Installati...UsersGuide.pdf

WBO2 says 1m from the turbo! (Page 2)
http://wbo2.com/lsu/lsuinstal.pdf

Innovate says nothing...
http://www.innovatemotorsports.com/s...C-1_Manual.pdf


Narrow band:
The factory have this right off the dumps pretty well... I'm planning to mount it about 12" back from the turbo, I assume this will be fine


What are people thoughts / experiences?

More info, 2JZGTE VVTi, with T78 turbo on ebay manifold, 3.5" exhaust


Cheers
Wilbo

[Duk]

Innovate are quite clear that the sensor should not be subjected to temperatures over 500*C and that the sensor should not be mounted so that condensation can be trapped within it (preferably not below 3 or 9 o'clock).
Any mounting that safely far enough away from the turbo (heat), I'd be at least 20cm away from the turbine outlet, before the cat and not able to have condensation pool/drain into it is ideal.

[wilbo666]

Yep, I can read PDF's too (When I said innovate say nothing, that is nothing in direct regards to distance... temperature isn't distance... )

I'd love to see some thermal imagery of my exhaust, or better yet the air temp inside the exhaust at min & max load, but alas I don't have that information, so I have no idea where the 'above 500deg C' red, do not cross line is meant to be Hence me asking ze question

And I don't have an exhaust temp probe that I can fit

1m is quite a far distance (WBO2), and would put it just before the gearbox xmember... that seems a bit ridiculous to me...(if I can measure...)

~610cm sounds a bit more realistic (PLX)

So I think I'll just put it at the bottom, pretty well around where the front of the gearbox starts, that sort of area

Cheers
Wilbo

[30psi 4agte]

wilbo
1m is right. It will put you about the gearbox xmember like so



Almost all wideband O2 sensors have their own heater elements in them. This is what the extra wires are for. they are heater wires.
Having too much heat for a wideband sensor is bad as they can overheat. You can actually mount the sensor at the exhaust tip and get good readings - you may have seen some dyno operators stick what looks like a wideband sensor up the exhaust tip when tuning. This is because it is just a wideband sensor.
The major difference with having it closer to the engine is the reaction time. This is the time the sensor takes to realise the current mixture ratio.
Its about finding the closest spot without getting the sensor too hot. Id err on the cooler side of things.

Factory sensors have no heater elements (most factory sensors some have wideband style) hence the single or two wires. They need to be positioned closer to the major heat source as they require the heat to sense the correct mixture and are calibrated to suit.

[wilbo666]

Thanks 30psi 4agte...

Most factory narrowband O2 sensors there days are heated as well by the way! Yet the factory mounts them very close to the turbo exit...check out how many factory sensors are heated when you are next at the wreckers, it's a lot!

Well aware of dyno operator style setups, and I've made and used one of these for a mate in the past.

Btw the extra wires come from the difference in how the sensor operates, not for the heater.

From WBO2...

Narrow band:


Wide band:





This also provides more info which I hadn't read in the past... apparently the heater heats the sensor to 600Deg C....http://wbo2.com/lsu/oxygen13-17.pdf

I guess further back is safer at the sacrifice of response as you say

Cheers
Wilbo

[30psi 4agte]

yep .sweet ......i see what you mean.
It has been a while sine i have had to look into the exact operation of the sensor. This is a bit of a refresher course
Trade school was 12 years ago. and there has been alot of scotch consumed in this time.

[oldcorollas]

further back is safer for overheating. the sensor can heat itself up to operating temp, just takes a little more current, but nothing drastic.
better to have it further away and take an extra amp for heating during cruise, than to overheat and continually kill sensors just to get an extra 0.01sec reaction time (which, btw, is much faster than the actual response of the criver circuits i am pretty sure)

fit just before the cat?

[BrianRA23]

I installed mine about 20cm in front of the cat due to concern about the heat generated in the cat itself and it also gave me the 1m of more from the engine.

I will be transferring it to another car soon and I will be getting a bung suitable for a k-type thermocouple welded to the exhaust nearby at the same time. This is just to confirm the sensor is not getting too hot as it will throw the readings off. The cost of an extra $20 for sensor and bung is small after you have purchased the wideband kit and display.