Oxyegen Sensor test procedure...found it!

[babasvr4]

Had all sorts of trouble finding this, listed under Fuel, EFI etc was expecting it under Emissions!
Hope this helps out those who may be experiencing excessive fuel consumption.
The connector itself is located in the centre console(remove the large side skirt)
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With thanks to Dave for explaining it so well till I could find the doc.

[kiwigalant]

Dude that's awesome info! I wish I had known how to do it earlier then I would've tested my oxy sensors already. Did dave give you any other tips or anything? I'm guessing because the oxygen sensor is removed and it suggests 'racing' the engine that it should definitely make the engine run rich and you can check the oxygen sensor says that?

[babasvr4]

Dave helped out because I couldn't find the doc on the procedure.
There are 4 wires, 2 black one white and one blue. The 2 black provide power for an
internal heater element at start-up I believe the other two being signal wires back to the ecu.
I think that in the case of failure the ECU uses fail safe values that run the mixture rich.
As my fuel usage has gone through the roof I thought I would check this out, at idle I get a value
or 80mv constantly so I think mine is ok...

[Davezj]

Dude that's awesome info! I wish I had known how to do it earlier then I would've tested my oxy sensors already. Did dave give you any other tips or anything? I'm guessing because the oxygen sensor is removed and it suggests 'racing' the engine that it should definitely make the engine run rich and you can check the oxygen sensor says that?

you don't remove the O2 sensor from the exhaust you just disconnect the plug and use some jumper wires to to fool the ecu into thinking the sensor is still plugged in, but if you leave the sensor plugged in you can just prob on the the blue wire thorough the back of the connector and see if the voltable changes on the the blue signal wire 0.6-1.0V you should see a change on it and 80mV is not enough to assume it is working 80mV is only 0.08V the snsor might be dead.
get the car warmed up and at idle the vitage should switch 0V to 1.0V quite rapidly.
or you can just plug evoscan in and monitor O2 sensor you will see it bouncing from 0V to 1.0V if it is working.

[kiwigalant]

Yeah I meant removed from the ECU haha. Alright I'll try that, just grounding to the chassis with the multimeter or through the plug ground?

[Davezj]

I am not sure, i would have thought you could use a chassis gnd to measusre the blue wire, but is that does not work then use the white wire.

i am not sure if the signal is refference to chassis or not. it probalbly is but don't know for sure. Try it and repot back with your findings.
you could alway try and oscilloscope on the signal wire which how i measured mine originally but i use evoscan now, it is good enough.

[kiwigalant]

I am not sure, i would have thought you could use a chassis gnd to measusre the blue wire, but is that does not work then use the white wire.

i am not sure if the signal is refference to chassis or not. it probalbly is but don't know for sure. Try it and repot back with your findings.
you could alway try and oscilloscope on the signal wire which how i measured mine originally but i use evoscan now, it is good enough.

Yeah would make it easier for me but probing connectors will have to do me for now. I was on youtube all night watching videos about testing other sensors so it's helped me understand the logic behind it, just have to couple that with what the voltage/resistance should be.

[babasvr4]

You know just thinking out aloud here, I may just swap my original out and replace it, not a lot of money and easy enough to do.
Small price to pay for peace of mind.

[wintertidenz]

Or spend a bit more and put in a wideband with narrowband emulation to the ECU. Means you can more accurately see your air/fuel ratio, and later tune it.

[Confused]

Nick Mann said to me that every VR-4 he's put a wideband O2 sensor into, even without doing anything else other than hooking up the narrowband emulation to the stock ECU, has resulted in better fuel economy.

I can believe that - a wideband O2 sensor has a very small window where it changes voltage output between 0v and 1v, a wideband is designed to read more accurately, and therefore, the narrowband emulation is bound to be more accurate.

For less than the price of a new Mitsubishi narrowband sensor from Camskill, you could have something like this PLX SM-AFR (http://www.ebay.co.uk/itm/301055623178) delivered to you. It's then only 3 wires to connect (2x power, 1x narrowband output) to the car's wiring.

[fassi1]

O2 sensor on VR4s responds very slowly at idele, at least 2000rpm is needed.
The reason for bad economy with stock narrow band sensors is their age, they are at least 14-15 years old so response at closed loop to ECUs changes to a injection timing is simply very slow and not very accurate. All the wideband sensors fitted to VR4s are brand new and that is the reason for better economy.
Old stock O2 sensor replaced with new stock O2 sensor will also improve economy as well as new wideband sensor.
At closed loop when ECU's target is lambda 1, usage of stock narrowband O2 sensor or wideband O2 sensor will result in exactly the same performance.
At open loop ECU ignores O2 sensor so it doesn't matter how old it is.

[wintertidenz]

With some widebands you can adjust where the narrowband emulation sits to adjust fuel slightly though - which, if you know what you are doing, can give greater economy.

[kiwigalant]

Might be a stupid question, but where is the plug of the oxygen sensor? I see the lead goes up into the passenger footwell, I'll try looking there, but if someone could give me a clue if I don't manage to find it that would be nice lol.

[kiwigalant]

Yep I'm stupid, found it on passenger side of the centre console. Took photos of the plug and where it is located as well as the procedure so I can write a guide. It's so hard to hold two probes in the plug with one hand or even with two. I'm going to make up the 'special tool' with some wire and connectors from an old/broken plug.

[babasvr4]

Pulled my O2 sensor out today after the new 4 wire replacement turned up.
Got to admit it was easy, expected an epic struggle under the car with the old sensor but it came out like
a granny's tooth!
Did the strip and join work in the cabin using the quick connectors supplied and run it while I data logged the bastard.
The previous sensor at idle showed a mass of vertical lines between 0 and .8v with no visible gaps, this one shows, again at
idle .2v -.8v but with a consistent spacing easily seen.
Something has changed, a few days driving should provide a little more evidence of either an improvement in fuel economy
or nothing...then I'm back to looking into injectors or boost leaks I guess.
Oh and the sensor!
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[434po1]

Hi guys

Quick question, I have just purchased a 2nd oxy sensor for my vr4, however, the plug has been removed. So I'm going to replace the plug from the unit I will remove, but my question is about the 2 black cables, does it matter which way round they are connected? I can't see any difference between them?

Cheers

Kevin

[Davezj]

Hi guys

Quick question, I have just purchased a 2nd oxy sensor for my vr4, however, the plug has been removed. So I'm going to replace the plug from the unit I will remove, but my question is about the 2 black cables, does it matter which way round they are connected? I can't see any difference between them?

Cheers

Kevin

no it does not matter which way round they are connected, it is just a heater element.