So I have a 1984 toyota dolphin RV with the 22R carburator motor that had a post cat O2 sensor made for the extra weight of an RV, I ost the exhaust system on the road and wound up putting in a new non cat system but lost the O2 sensor that was after the cat. Gas milage started to go down after about 3k miles when my OBD1 started to adjust, now with the O2 sensor not present to "close the loop" the motor runs rich.....i know there are heated and non-heated O2 sensors but how do i know which one i have??? Will those Universal two wire O2 sensors work?

 

Maybe I'm way off base here and carbed Toyotas had features that I am unaware of.
How is an electronic control system able to act on a carbed engine? Electrically varible jetting, or such???
I can see that a post cat 02 sensor could keep tabs on cat efficiency for emissions testing purposes, but for engine control??
Please educate me about this.

 

All the early 22R engines I saw had the o2 sensor before the cat

Why yours would be down stream from the cat I can`t see why it being a motor home would make a difference.

Most of the early O2 sensors are one wire.

What happened to the harness connection on yours the plugs should still be there unless that was just cut off when the exhaust was replaced.

 

I worked on a California Emissions truck that had an O2 sensor on it as well. I was surprised to see it had one and I know the truck was in original form. Being and 84, it should be the single wire one in the exhaust manifold. I too am not sure how an O2 sensor can really work on a carbed truck. There is a little mini computer in the passenger kick panel that controls it. It is only on California Emissions Models from my experience.

Toyota did not use the 4 wire sensor until 88 and then it was in the exhaust pipe near the transfer case area. Being a Dolphin, I cant see why it would be any different then any truck unless yours is just something really different. Under the hood on the passenger side, there is a label ( if it is still on there) telling which truck you have. It will be Cali Emissions or Fed Emissions.

Stay away from Bosch and Universal sensors. They are great for other trucks but not Toyota.

Here is the one I am sure you need. http://www.sparkplugs.com/Automotive-Sensors-c239.aspx DEN234-1056

Here is where you should have the sensor for an 84.

 

I have also never seen an '84 Toyota pickup with a downstream O2 sensor. I have seen the RV manufacturers extend the exhaust, frames, drive shafts, etc, but not the electronic controls of the engine. If anything, I believe it could have less emission controls because it is in a heavier duty weight class.

The O2 sensor should be on the manifold, as the picture by Terrys87 shows. In my experiences working on these trucks, including some RVs, O2 sensors in those years were only on California smog models, where the signal are processed by the computer and the mixture is controlled by a device called an EBCV. The EBCV controls the mixture in the carb by a small amount. I think it is able to release some of the pressure drawn by the venturi, but I am not exactly sure. I would actually like to know if anyone knows for sure. There is also an EACV, also controlled by the O2 sensor and computer, that lets air into the exhaust so the catalyst can work optimally.

Are you sure that it was an O2 sensor? I parted out a Toyota motorhome once, and the motorhome part was definitely not Toyota quality. I could easily see a wire from the motorhome falling off or getting torn and looking exactly like an O2 sensor wire.

There is no system in a carbureted Toyota that is going to adjust after 3k miles. If it ran good for that long then something else is the problem.

 

I had a 83 Pick up with the 22R

It had a O2 sensor it was in the exhaust in front of the cat in fact the wire for it had a grommet in the drivers side floor .

Been a few years I don`t recall just where.

 

I have seen Cali Emiss Models and the Fed Emiss Models. I understand the Canadians have models that is still yet a little different. I have not seen a Canadian model and wonder if that is possibly something different as well?

 

Imported to Canada would not have to meet the USA Emission Standards.