Hello at all,
I have a '94 samurai with a G16A engine on it with its own ECU but with the orginal 1.3 wiring sistem.
I have to swap the O2 Sensors, My original Samurai's Sensor have 4 wires, the Vitara's Sensor have 3 wires, i don't know how to connect the 1.6 new sensor on the 1.3 electrical system.
I tried to search some informations about the differencens betwen the two wiring sistems, and betwen the functioning of the two sensors, but i didn't find nothing specific for what i was looking for.

I took some photos of the different sensors, and connectors that you can see as attachments

I wish that you can help me

Thank you very much

A 4-wire O2 sensor has two heater wires, an O2 signal wire and the O2 signal return wire
A 3-wire O2 sensor has two heater wires and an O2 signal wire, the exhaust system itself acts as the return.

Connect the three wires that you have and ignore the fourth - the polarity of the heater wires is not important.

So the two pink wires are the heater and the black one is the signal that i have to connect to the ecu?

Probably - but - you really should be checking the wiring diagram for those details.  I wouldn't  be attempting a swap of that nature without the diagrams for both vehicles.

I have diagrams, but they don't show the colours of the o2 sensor's wires.

Checking with the voltmeter touching the two pink wires i have a resistence (very low),  if i touch the black wire and one of the two pinks i have no continuity at all.

I tried to connect the two pinks wires directly to the battery and i felt the sensor slowly gettin warm.

Can this be useful to identify the tasks of the wires?

Don't the diagrams show the pin-outs of the connectors?

The diagrams that i found doesn't shows the colours of the o2 sensor's wires, just the colours of the wiring harness coming from the car.
I'll try to connect the two pinks wires at 12v and the black one to the A19 ECU terminal, taking them from the original connector, and i'll exclude the signal sensor return like you said.

Searching on the web i found this image, that explains the tasks of my original 4 wires o2 Sensor so now i know how to connect (my original o2 sensor is DENSO).

I'll give a try i woldn't shot anything (I wish) and the worst thing that it can happen is that i will have a bad fuel cosumption.

Thank you, you've been very helpful!!!

I'll write if this configuration wil work

Ok the car still not working, and runs better with the original oxygen sensor

Try grounding the fourth wire - the o2 sensor return

This is a nice idea, i'll try!! Thanks as always

I Was wrong, the car runs the same way with both sensor ( Last time i used the car i tried to rotate the distributor and i left it in a wrong timing position, this was the problem).
The car has still the same issue, it works only with the Temperature sensor unplugged and of course runs very rich ........

It appears that the 3 wire systems typically run with both heater 12v and heater grnd wires, and O2 signal wire (voltage) using motor as signal ground .   Make sure that both your computer and motor are grounded,  Bad grounds distort everything.

I tried to ground the engine better with a jump start cable in the previous days, i didn't checked correctly every ground in the engine bay, i'll try but i don't know if this can be the problem.
This Malfunctioning is quite tough to find .......

I tried to ground the engine better with a jump start cable in the previous days, i didn't checked correctly every ground in the engine bay, i'll try but i don't know if this can be the problem.
This Malfunctioning is quite tough to find .......

Other than grounds which are underrated in importance, I would give up on using the 4 wire O2 analyzer and get a three wire plug and O2 analyzer.  If you need to use the 4 wire equipment, wire the O2 sensor ground to the heater ground.  I do not know how you spliced the wiring to the Vitara ECU, but there should not have been a place for the O2 sensor ground at the ECU plug, so you could run it to the ECU ground also.  (My problem with this is that on newer ECU's the there is a resister to ground and the computer checks that voltage for a value to ensure continuity, and "0" isn't acceptable).
Having spliced in a few motor swaps, I would check that the ECU points are going to the correct O2 sensor wires. 

Quote from: LOE92 on February 12, 2017, 10:22:19 AM

I tried to ground the engine better with a jump start cable in the previous days, i didn't checked correctly every ground in the engine bay, i'll try but i don't know if this can be the problem.
This Malfunctioning is quite tough to find .......

Other than grounds which are underrated in importance, I would give up on using the 4 wire O2 analyzer and get a three wire plug and O2 analyzer.  If you need to use the 4 wire equipment, wire the O2 sensor ground to the heater ground.  I do not know how you spliced the wiring to the Vitara ECU, but there should not have been a place for the O2 sensor ground at the ECU plug, so you could run it to the ECU ground also.  (My problem with this is that on newer ECU's the there is a resister to ground and the computer checks that voltage for a value to ensure continuity, and "0" isn't acceptable).
Having spliced in a few motor swaps, I would check that the ECU points are going to the correct O2 sensor wires.

I know that Grounds are importants and Considering that i changed the engine is possible that something that before was grounded fine now is not grounded well and the ecu is reading some wrongs values so i'll try to disconnect every ground and clean the eyelet and the part of metal where it must be tighteen on (even if i did this when i mounted the 1.6 engine).
About the O2 Sensor, i'm actually using the 3 wires sensor (From Suzuki Vitara), and i can't tell for sure if the engine is working differently than before when i was using the 4 wires sensor because the car is still not running fine for the other undefined problem and after doing this test i know that is not caused by the O2 sensor.

Sorry for my english is not my first language , i'll hope that is understandable and thank you kindly for your help!!!