o2 sensor repositioning or deletion factory 2jz ecu Question

["Z" UTE]

Guys I have run into a minor hurdle with the 2JZ-GE install into the old Crown ute. The factory ECU and loom supports 2 x o2 sensors one for the first batch of 3 cylinders and the next one for the rear batch of 3 cylinders. These sensors on the factory manifold are located just before the cats.

Problem is I can only fit an exhaust manifold that has provision for one o2 sensor.

Questions are can I delete one o2 sensor by fitting a delete emulator, something that supplies a constant voltage, or would I be best bunging the one available hole in the manifold and relocating the pair of o2 sensors further down stream in the exhaust? Will extending the loom by about 1 metre to accomplish the repositioning have any detrimental effect on the senders output? These are the 4 wire o2 sensors.

Yes I have tried 4 different exhaust manifolds and I am stuck with the single o2 orifice manifold, or a full custom set of extractors, not really where I want to spend a bucket of dollars.

Any definitive answers here would be hugely appreciated,

cheers Chuck.

[thechuckster]

better to just shift them further down the exhaust. Being 4-wire sensors they heat themselves up and thus don't need proximity to the head to get warmed up quickly.

extending the loom won't matter, just make sure they point downwards wherever you fit them.

just make sure they are ahead of the CATs.

["Z" UTE]

Thanks Chucky, that was my line of thought, had a chat with the son over tea tonight and he confirmed what you have said. Busy motor mechanic/auto electrician son. You would think he would be a lot of help to the old man, but he hates cars! As for cats, I will not be fitting any of those nasty bastards. Old 1970's commercial vehicle should get me by that reg.

cheers Chuck.

[e30-323ti]

Can you not splice/split the input/output to the one O2 sensor??

["Z" UTE]

Splicing the o2 sensor wires has become a moot point. The one orifice available in the manifold would position the sensor in such a way that my steering box could not be fitted, so will be putting them in down stream.


That being said, from my understanding, an emulator connected to one o2 sensors wires instead of the sensor, would give a constant perfect range o2 analysis, the ECU would then only be affected by data from the remaining connected sensor.

The emulators are commonly used in the good old usofa when guys use an aftermarket ECU, particularly on motorbikes,


cheers Chuck.

[thechuckster]

O2 sensor data is only used on cruise and warm idle. Given the perilous nature of fuel prices, anything that lets you balance economy with performance is a good thing.

Also, if the ECU discovers that one sensor is rich and the other is lean it may report an error or do something worse. It will also get confused during trailing throttle (decel) as the ECU will cut fuel and get mismatching signals.

It's a minor PITA to fit the sensors but it's less sensible to fudge sensor data.

[wagonist]

seeing as you've got to relocate them anyway, you may as well fit both.

But would there have been any issues soldering the 2 output wires back to the ECU together so that there was an identical signal?

Sorry for the hijack, but I've got a similar question where I need to relocate a 4 wire sensor from out of the cast manifold near the head (the original has a cat welded into the manifold) to further downstream? I'm guessing 1 metre by the time you go from in front of the engine near exhaust ports (FWD car) to somewhere between the engine & firewall.
I would like to delete it too, but the car spends time just idling & driving "normally".

[dumbass]

If u have to lengthen wires,
Lengthen the engine harness side as they are normal wire
And not the oxy sensor wire as they sometimes are stainless

[wagonist]

good advice.

I'm still curious about the connecting of the wires together. In my situation, I may be going turbo later, which means probably moving the O2 sensor back to the dump pipe on the front of the engine.
If I solder "parellel" wires to the existing (but make sure that 1 plug is left empty), will the ECU get confused?
Much easier to do now while the loom is out of the car & being modified.

But I'm sure others would like to know if twin O2 sensors can be tricked into both reading off 1 by just soldering wires together.

[thechuckster]

Well the ECU is measuring voltage on the O2 line relative to the ECU Sensor earth (whereas for a temp sensor or TPS the ECU is working out the resistance to ECU sensor earth). And from a distant memory, I recall someone saying/writing that the O2 sense circuit would have a high impedance interface ... so in theory you could get away with bridging the O2 sense pins and just using one sensor.

but that's just a wild guess. Would be easy to test on the bench i suppose?

[wagonist]

ok, so seems like an emulator seems to be the alternative if one of the sensors needs to be deleted.

In my case, I'm probably better to cut the wires at the back of the engine & fit a new plug for the O2 sensor there
But then fit the opposite plug onto the rest of the wires at the back of the engine, so that if I decide to relocate the sensor to the front later, I can unplug the sensor at the back, plug the loom to the front of the engine in & then replug in the O2 sensor in its "original" spot at the front of the engine.
This is if someone happens to fit a 2nd sensor for whatever reason, only 1 will be active.

Confused...

As long as there's continuity in the circuit, should an extra plug matter?

["Z" UTE]

Yeah was definately thinking of lengthening the main harness rather than the o2 snesor cables. Would suck balls later on down the track to have to do some rewireing just to fit a new o2 snsor.

Wagonist, as far as leaving the plug "dangling" that should not be a problem, as you are now recieving info from the extended parrallel wires. Effectively leaving your existing plugs intact and simply fitting additional plugs on the parallel wires, sounds lke the way to go.


If you google o2 emulators, you will find some home buildable circuits, Jaycar is your friend for all small electronic bits. The guys will be extremely helpful if you are trying to do something out of the ordinary. Gets there grey matter stimulated rather than having to answe bumb ass questions about how to plug a blue Ray into an analogue TV!


cheers Chuck.