YotaChick86

I am doing an engine and tranny swap (also swapping computers) with an 86 22re 2.4 4runner manual that was wrecked, but the engine and tranny are good and an 89 22re 2.4 4runner automatic that has a good solid body. After removing everything from both vehicles and cleaning up and replacing parts I have run into an oxygen sensor problem!
86 engine has a 1 wire oxygen sensor on the exhaust manifold
the 89 had a 4 wire oxygen sensor on the exhaust under the drivers side.
Can I use 89 oxygen sensor on the exhaust since the hook up is there or do I need to rewrite the whole thing to do the single wire from the exhaust manifold?! Does it make that big of a difference?

Hadmatt54

The 4 wire O2 sensor has a heater circuit so that it comes up to temperature more quickly and sends info to the ECU faster, that should be the two black wires. There should be blue and white wires as well and this is the sensor circuit where the computer sends out a voltage signal generally 5 volts on one wire and receives a voltage back on the other wire. This return voltage varies as the sensor resistance changes due to changing conditions in the exhaust stream. This is how the ECU monitors the amount of O2 in the exhaust and as a result makes changes to timing, injector pulse, etc.
The single wire O2 sensor is not compatible with the ECU in the 89, it's older technology...no heater circuit and 86 ECU would send out a signal, monitor how much went to ground and make changes to timing, ect. based on that info.
I think that you have another problem... You are swapping engines, transmissions and ECU's, but you haven't said anything about wiring harnesses and you need to.
The 86 and 89 are not the same, you need to go either all 86 or all 89, you can't mix them up and though they might plug together here's why.
Up until August of 88 the 22re had low impedance injectors, with a ballast resistor wired into the injector circuit. The injectors have a resistance of approx 1.3 ohms and the resistor is a aluminum (silver) box located on the passengers side inner fender, but it's wiring is part of the body harness that comes into the engine compartment from behind the passengers side fender. It's not part of the engine harness.
After August of 88 the 22-re had high impedance injectors and no ballast resistor. These injectors are approx 13.0 ohms. Your problem is this that you can't run the low impedance injectors and resistor with the 89 ECU or the high impedance injectors with the 86 ECU, doing so will burn out the injector driver circuit of the ECU, so you have a couple of choices.
1) swap the entire 86 body harness, 86 engine. transmission, associated harnesses and ECU into the 89.
2) Remove the 86 engine harness and injectors from the 86 engine and install the 89 engine harness and injectors into the 86 engine and use the 89 ECU. To do this you have to remove the intake to get to the wiring and fuel rail.
Personally I'd go with #1, because you are going from an auto to standard, your clutch switch, clutch cancel switch would all be plug and play. Your 86 cluster would be for a standard and would work, sometimes you have to change some of the pin configuration of the wires on an auto cluster. The only fab work would be drilling the holes for the clutch master cylinder in the proper location and installing the bracket for the clutch flex line and cutting the hole for your shifters in the proper location.
One draw back is if you have emission testing where you are you may have to go all 89, because the state won't let you go back in technology. The problem with this is you get into having to wire in the clutch switch, clutch cancel switch, etc.
Hopes this helps. good luck!