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I decided that it was time for a new o2 sensor as the one i have has over 315000ks on it. Did a little research and found that the 4 wire sensors have a inbuilt heater and a dedicated ground (as apposed to the ground being through the exhaust manifold)

So i bought one off ebay for about $50

I decided that i would pick up my ground (black wire) and 12v supply (black wire with white stripe) from the check connectors near the drivers side strut tower. The sensor output i connected in the stock place near the gearbox.
The sensor came with hi temp glass sleve and i added that ribbed covering as extra protection.

Voltmeter was playing up so i cant give you a reading or see if it was working.

Unfortunately my camera batteries died as i was walking back inside to upload them.

Any questions?

Can you get some new batteries to upload the pics?

On a serious note, other than the voltmetre check that hasn't happened yet, does the oxy sensor seem to work better when cruising around?

Cheers

Ok here are some pics

This is where i connected the heater wire and the ground. The Black/white wire is the 12v positive and the Black wire is negative



This shows the cable with a 4 pin connector on it (i stole it off the old fuel tank sender) that enables me to remove the o2 sensor if needed.
I crimped and heatshrinked all connections and added some ribbed cable trunk as well. You can see the fibreglass sheath from the o2 sensor to the new 4 pin connector

nice... might have to get me this setup too...

One question... those two plugs that you sourced ground and 12v, i thought they were some sort of diagnostic plugs for subaru dealerships to read from... would this have an effect on the ECU or am i totally off point, meaning that what you've done is all good?

Cheers

umm..does the sensor need a constant power supply in a 4 wire factory equipped car or does ECU turn power off at op temp ?

4 wires - you have not named fourth wire ??

pwr, earth, ecu, ????

Does it make a difference to car running/fuel consumption?

jono wrote:umm..does the sensor need a constant power supply in a 4 wire factory equipped car or does ECU turn power off at op temp ?

4 wires - you have not named fourth wire ??

pwr, earth, ecu, ????

I picked up the power from the same supply as where the californian l series sourced it, (it had a 3 wire sensor), its on whenever the ignition is on.
There are 2 grounds, one for the sensor, the other for the heater, they are just joined together.

On the sensor, the 2 white wires are the heater (one 12v, the other ground) the black is the signal output to the ecu and the grey is the signal ground (joins to one of the white wires)

I have noticed it runs a bit smoother (not straight away, but i think the ecu had to learn the new sensor) and i havent filled up since i installed it so i cant tell about fuel comsumption.
One thing i did notice is that the green LED on the side of the ecu (o2 monitor) now flashes a lot quicker

This is the one i got... http://cgi.ebay.com.au/OXYGEN-SENSOR-O2 ... -UNIVERSAL

I see that seller has both the 3 wire and 4 wire sensors for sale in his ebay store. Forgive my ignorance, but why would one use a 4 wire as opposed to the original 3 wire? I thought the 3 wire also had a heater and if not then why is one beneficial?

two earths ? four wire sounds better than three ?

Yeah the 3 wire has 2 heater and a signal wire, the signal ground is still through the exhaust pipe like the 1 wire one

My EA82T L series with 3 plug ECU looks like 1 wire to me, does this sound right or am i looking on the wrong place?

yeah they were all one wire ones, except for some califorlian models, they have much tougher emissions laws. I think some jap models had a second sensor after the cat too.

and some markets did not even use an O2 sensor at all ! teaching me that all efi's do NOT need an O2 senor if set up as such from factory. eg VK commondore efi of 1984

The 3sfe (twincam 2l)Toyota Camry is another that didnt have an o2 sensor.

I think that the EDM ea82T did not have an o2 sensor either, from what ive read on the USMB

Its mainly a emission control device, and assists in fuel economy

It basically gives the computer a voltage feedback so that it can adjust the light throttle mixtures to keep the cat converter in its temperature efficient window . I would not remove one if the engine had it std , fuel consumption can suffer if there is no feedback signal .

A .

discopotato03 wrote:It basically gives the computer a voltage feedback so that it can adjust the light throttle mixtures to keep the cat converter in its temperature efficient window . I would not remove one if the engine had it std , fuel consumption can suffer if there is no feedback signal .

A .

I thought the o2 sensor was there to keep the engine running at optimum fuel efficency, not to keep the cat converter at its temperature efficient window... how do carbie fed engines get around this?

Cheers