4AGE O2 sensor comfirmation....

[BNU77S]

G'day,

I'm most of the way threw a 4age conversion into my lil TA22.

I got a set of extractors made up but it needs a screw in 'bung' type of O2 sensor.
I never got the O2 sensor with my half cut and I want to make sure I get the right type.

I've searched on her and there is a lot of talk about them but I can't find any definate answers. Or i'm to excited to read

So basically what screw in o2 sensor should I get?
Single wire, 4 wire, what? I'm so close now and I don't want to be waiting for the wrong part to come in.

Any help would be greatly appreciated

[oldcorollas]

the signal from a 1, 2, 3 or 4 wire sensor is the same and can be used by the ECU.

the first differences is whether the sensor tries to ground throuhg the exhaust (1, 3wire) or if there is a dedicated ground for the sensor (2, 4 wire)
the second difference is if the sensor is unheated (1, 2 wire), or if it is heated (3, 4 wire)

heated is better than unheated, as you can put it further away from engine.
dedicated ground wire for sensor is better than relying on the electrical connection from the sensor housing to the exhaust, to the head, to the block, and eventually back to the ECU.

but in the end, any of them will work.

[BNU77S]

So any screw in one will work but a heated 4 wire is best.

[oldcorollas]

yes, you can make any work, with a couple of extra wires, and 4 wire heated is best.

[BNU77S]

Thanks for the help. Can't wait to get this thing on the road

[toyoda]

The heated sensors are controlled via the ECU using a Duty Cycle that varies across the driving range plus measuring resistance via a pulse.
As Old Corolla says use any of the 02 sensors and just use the sensor side - not the heater side.

Toyoda

[oldcorollas]

do stock ECU's do that for narrow band?
i've only ever seen ones that turn the heaters on, and the increasing heater resistance with temp reduces the current and maintains the temperature...

you would not use a heated sensor and not connect the heater.

[toyoda]

Yep, For Narrow band 02 as well as wide band A/F.

E.G. : ( DR = Duty ratio)

A= after the engine is started, the heater is controlled at 100% to heat up as fast as possible.
B= Once the O2 or A/F sensor generate a signal, the heater controls by estimating the sensor temp, based on initial air and coolant temp.
C= from here onwards the ECU controls the heater element based on driving conditions. At low vehicle speed/load the DR will increase
D= during idling the DR will increase even more to keep the sensor temp at level
E= since more and hotter exhaust gasses passing the sensor, the heater doesn’t need to be activated to keep the temp high

[oldcorollas]

wideband is totally different conotrol tho..

do you have any documentation about heater control of the narrow band sensors?
i had doc from Bosch (or NTK??) to say that heater power was just 100% all the time, and the heaters resistance controlled the current as temp increased.... but of course now i can't find it

[toyoda]

As requirement for Euro IV, the heater element of a O2 sensor needs to be monitored once / trip. The ECU performs this by measuring the current the heater element is drawing. With a standard resistance value of 11-16 Ohm at 20 degrees to 23-32 at 800 degrees, the ECU has a window in which the current can fluctuate. All current measurements outside the window are considered as heater failure.
High current detection threshold is 2A (cup type) or 3.5A (planar type)
Low current detection threshold is 0.3A. To check for low current, the heater should be warmed up and engine conditions should be as such that the sensor needs only a DR control to keep its temp high enough (conditions A and B)
Intrusive heating is a fixed DR control onto the htr element to monitor the low current flow


Old Corolla - Pm Me your Email Address and I will see what I can send you - it will be PDF though.


Toyoda