unheated O2 sensor?

[mechyank]

My charging system is marginal as stock and would certainly not like the extra whatever amp load for a heated sensor. I am using the O2 sensor for fuel economy on a 1100 motorcycle. When I need it most is at cruising speed and the exhaust is sure to be hot. Can I just use an unheated O2 sensor?

[800vtwin]

depends if you want a wideband or narrow band o2.

-narrow band will indicate if mixture is above or below 14.7:1 a/f. (and thats it)
-wideband will give you mixture readings between 7:1 to 22:1 a/f. (or 10-20 on some)

Yes you can run a single wire narrowband sensor with the microsquirt, and use ego control during cruising.

[mechyank]

I'm not sure why someone would want to use a wide band O2 sensor. I think a narrow band sensor would be fine for me.

Next question is whether I want to go with a one wire sensor or a two wire sensor that has a ground wire? I remember reading that it is better to have all the grounds connected at the same point as to avoid ground loops.

[mfro]

I'm not sure why someone would want to use a wide band O2 sensor. I think a narrow band sensor would be fine for me.

Guess it's depending on what your main goal is. If you're main target is fuel efficiency (and you're not restricted by emission control regulations), you'll most likely reach maximum efficiency with maximum power output.

Propably against popular belief, maximum power for a internal combustion engine is not reached at stoichiometric mixture (λ=1 equals to an AFR of 14.7:1) but when running slightly rich: λ=0.83 - λ=0.9 which equals to an AFR of about 12.2 to 13.2.

Narrowband sensors basically only clearly indicate a small mixture band around λ=1 because they are designed to maintain ideal operating conditions for catalytic convertors. They're not really suitable to exactly measure richer AFRs.

[800vtwin]

One would use a wideband to actually know the a/f of their engine. There is no other way to tune fuel. Checking plugs is meaningless on efi. (it worked well on a 3 circuit carburator, but not on a 144+ cell table plus correction factors). Forced air is even more dangerous to tune. Its impossible to build a fuel table without a wideband.

I've never heard of anyone thinking best power was at stoich. (best emissions/complete burn with no fuel cooling). Rule of thumb was always 12.5 for peak torque, 13 for peak hp- but many engines like what they like, even up to 13.5 or 13.7.

Using a narrowband will get you huvering around 14.7 at cruise, but you could go as high as 17 for cruising if you used a wideband. If overall fuel economy is your goal, proper tuning of the whole fuel table will give you best results..

[mechyank]

Ok so wibeband helps in tuning. There are people whom I can get tables from that have the exact same bike. Am I sacrificing anything in going with a wide band O2 sensor compared to to a narrow? Resolution? Can you get unheated wide band sensors and is there a price difference?

[24c]

Can you get unheated wide band sensors and is there a price difference?

AFAIK, there is no such thing, as the only unheated ones are one or two wire narrowband sensors, which have a longer life, but don't work well at idle or under low loads (when there is insufficient heat in the exhaust)...so that's why heating was developed.

PS The price difference ? Widebands are usually more expensive than narrowbands, but they also need a controller...more expense!

[mechyank]

AFAIK, there is no such thing, as the only unheated ones are one or two wire narrowband sensors, which have a longer life, but don't work well at idle or under low loads (when there is insufficient heat in the exhaust)...so that's why heating was developed.

Under low loads unheated sensors don't work well? What do you mean thay don't work well? You mean like cruising? I'm not concerned about Idle. Thanks for the information on O2 sensors all.

[Peter Florance]

I think if you locate your narrow band close enough to manifold, it will get hot even at idle. You'll have to test that to see if it works.

[800vtwin]

I wouldn't rely on someone else's table. There are many reasons:

- you are relying on them for proper tuning.
- what if you want to change something? or something isn't identical? (even an air filter or exhaust changes requirements.)
-actual fuel used.
-who says your engine requires the same table, even with exact same engine configuration, fuel plays a huge role. For instance, in canada- any product sold/developed from the usa will be way rich here. (like a pipe manufacture giving jetting specs for their exhaust- it doesn't work here, rule of thumb is jet 4 sizes leaner) Our fuel has a higher btu content/ better. Same with efi maps- they're way too rich for us. I am sure different parts of the usa as well as canada will all be different, as fuel is made/ imported from different places.
-then there is altitude. A fuel table developed at sea level and then used at a different elevation with a correction factor (say 4000ft) is NOT the same as a developed table at 4000ft with no corrections applied. (Air temperature tuning/ corrections has the same issue's).

Tuning for where you live (altitude and temperature), how you ride, weight/load/gear ratio the engine see's and the fuel you use is by far better (and safer) than just having a running engine from a borrowed table.

If you had a wideband, you can tune your whole table to the a/f ratio you want, even cruise,idle , then just remove the sensor. I'm sure your charging system can withstand the small draw temporarily. You don't need it fulltime. And whenever you do a modification, now you have the ability to just retune. (even tune your buddies bike) A wideband is a handy tool.


(the only reason cars use ego feedback fulltime is because of what I said - fuel and correction factors are not perfect, so finer full time tuning gets better emissions/milage in a wider range of enviroments)- but its not needed.