Wile E. Toyote

I have an '88 truck with a 22re. It has the 4 wire O2 sensor that goes in before the cat. I don't have the flange on the exhaust to place it there. I have an exhaust manifold off an '86 that had the single wire sensor on the manifold.

What issues could be raised if I put the 4 wire sensor on the manifold? Should I just put a flange on the exhaust and keep it there? If it doesn't matter then why did toyota move it in the first place?


Thanks for an help you can offer.

Flash319

I would not move it. I would think that the placement is there for a reason. If it is to close to the ports it may react to fast causing a constant condition. The ECU monitors at timed intervles and this may throw it off.
Although it may be fine as other vehicals use the one at the manifold only (honda civics).

abecedarian

Take the truck to a muffler shop and have them weld the proper flange / bung in. Even if they don't have one on the shelf, they're easy enough to fab.

Wile E. Toyote

Thanks for the advice.

abecedarian

Also, if you ever need emissions testing done the O2 relocate will likely fail you on a visual inspection. Not that it wouldn't work but there are reasons Toyota moved the sensor downstream... probably to give the PAIR system output time to mix with the exhaust gasses for a more homogenous reading.

Either way- good luck.

Wile E. Toyote

I was hoping that a cheap half a$$ed wire splice would do the trick. Just my lazy side piping up.

abecedarian

may work... but how would you splice a 4 wire sensor into a 1 wire harness?
I could see leaving the two heater wires alone, but then you have 2 other wires left over....

Wile E. Toyote

No I meant just lengthen the 4 wires. I have the 4 wire harness and a manifold with the mounting location for the older style.

22RE_David

I'm not sure as to what will happen, but I know what you're talking about and wanting to do. I have an '89 4Runner and I got a split in my down pipe because one of the hangers came loose and the pipe eventually broke in two from the crack line.

Currently, I have a horrible exhaust flex tube from AutoZone as a temporary fix and I don't want to use this much longer. However, a buddy of mine just got a header and made a full exhaust for his '85 4Runner, so he gave me his manifold and down pipe.

Problem is, like yours, my 4 wire setup is located by the catalytic converter instead of the manifold like in his 1985 setup. I'm going to go ahead and try to install his exhaust manifold and down pipe and re-route the wires and see how it works. I'm assuming that it can't be any worse than my flex tube setup as this system has terrible leaks.

Sure, I'm skeptical about how well this will work, but I'm on a tight budget with a baby on the way and it's at least worth a try. Also, I don't think you'll have to splice any wires. It appears that the wires run under the carpet and may be just long enough to reach the manifold if pulled out and relocated.

I'll post pictures of my results when I'm done.

Hope this helps!

nv4runner

Most O2 sensor wires are also shielded, as this circuit deals with millivolts and any interference would wreak havoc with the computer and injector pulse width. If you have to splice try to make sure that other wires do not cross or parallel the spliced in section.

22RE_David

It was just as I suspected. You can pull up the carpet and move the wires to a different location, with plenty of room to spare. I took pictures step by step, as I was doing it, so you should have no problems doing this. I'm going to write up everything and post the pictures in a little while. I've just got a little work left to do, but I'm essentially done.

22RE_David

Ok, I must warn anyone who attempts this.
I got the relocation done with no problem.(sorta)

I've run into a clearance issue withe the pipe from the 85 4runner running from the manifold to the catalytic converter.
The flange that exits to the cat is right next to the torsion bar mount and I'm not able to bolt back up to the original exhaust.
What's gonna have to happen is I'll have to cut the pipe earlier up and put a curved pipe in so I can mount the old exhaust unless I can somehow bend the pipe from the 85 4runner myself which seems unlikely at this point.

I will still post the pictures for anyone who is still interested though.

Wile E. Toyote

David thanks,
Let me know how it works out for you. I won't have the same problem with the exhaust pipe that you have, cause I have no cat at all right now. Also it's all frankentruck anyway. It is an extended cab on a short frame and currently have no bed. The exhaust I have is just one I picked up on CL for the time being. The exhaust is on, if the move works out for you I'm going to swap out the exhaust manifold and move the sensor.

Thanks for being the guinea pig.