There are several things with nothing connected but not sure which it should be. If in fact this thing should have a one wire oxygen sensor. Anyone have a pic of where the one wire ones connect?

 

Here's a Youtube of a guy testing it on an 86 PU:

Try googling "86 4Runner O2 sensor wire" and hit "images" and you'll see some pictures.

 

If it is a 87 or older engine that who ever did the swap just bolted the exhaust manifold from the vehicle back on.

Thus you have the O2 sensor bung in the pipe in front of the cat when if this is the engine harness from a older engine the O2 sensor harness comes out of the ECU across the front of the truck in the split loom with all the other wires

To the area at the coil and igniter then down to the O2 sensor

If I could find my camera it hides all the time it gets lazy then find the charger I would take a picture

 

85-87 have the O2 sensor in the exhaust manifold. The newer trucks have the sensor in the exhaust pipe and is near the transmission/transfer case. What color is your injectors? White is 85-87, red can be 88-95. If you can post a picture of your engine bay, there are other things that can help identify what you may have as to which Test Connector, if you have a sensor in the thermostat housing, which plug is on your wiper motor, What is the date code on the drivers door jam?

 

Thinking about this some more if there is no hole in the floor by the drivers seat then this can`t be a 88 it might be titled as a 88 .

Just what does the plate on the door say for the production date??

Life in working on older Toyota vehicles is never boring

Put a used exhaust system on??

Got the one for a 88 now the bung for the O2 sensor is not where it should be and now a 4 wire sensor and nothing to plug it into

 

The door plate will tell what year and month it was made. I forget which month it changes model. It is September or October I think??

 

I believe that it is actually a 87. I will have to double check the VIN plate when I get home. I know that the exhaust on it isn't right, as it doesn't quite line up right. I believe it came off the wrecked 89 that I have. Pretty sure at this point that it should have had the sensor that went into the manifold. Anyone have a good picture of the connector that the one from the manifold should hook up to? At this point I am 99% this is what is going on.

 

A signal wire connector round at one time yellow most likely weathered with age with a black wire

 

I believe that I know which one that you are talking about. Pretty sure it is laying somewhere on the fender right near the coil. Question. Is it possible to connect the 4 wire that is currently downstream in the truck to this plug and it still operate?

 

It depends on just what ECU you have in the truck!!

If you have the one for the 88 or 89

It will have the pin outs on the ECU to run the 4 wire O2 sensor

All the heater circuit does is heat the sensor to the exhaust temps get hot.

To put it simple you have a big mess

Figure out just what year you want it to be then change things as needed so all the parts play well together.

That is about the easiest way to get things straighten out.

 

How can you tell the year of the ECU? I don't care what year it winds up as long it is alright. It runs fine now just have the CEL coming on until you let off and get back on it. The codes show just the oxygen sensor. The port you paper clip to get the codes jsbtge old round yellow one that plugs into the rubber boot on the fender.

Other than the light it runs pretty good. I've been driving it like this for about 3000 miles now

 

From your description of getting the codes, using a round port and a paper clip, you have an 85 or 86 setup on the drivers side.. The 87 and newer has the square port on the passenger side.

From my experience when a CEL comes on and off due to acceleration and deceleration, is usually due to a vacuum leak.

On the cover of the ECU there is a 10 digit number (xxxxx-xxxxx) sometimes you can put those numbers into Google and it can bring up what year the ECU goes to. It has been a long time ago since I tried it but there are some Toyota part sites that will let you enter those numbers and tell you what year the ECU is for.

 

If you have the round port with the clip in it like the picture in the video, it is 85/86.