Challenger

So my 85 22r pickup has an o2 sensor on it. I thought that the o2 sensor was only for efi vehicles so it can tell the mass air flow sensor more/less air. Am I wrong?

drew303

Your wrong.

look behind the passanger side kick panel. There is a Emissions Control Module (ECM)

don't ask me what it does... cuz I have no idea

yotakorey

I had an 85, 22r with the same 02. never had any issues

myyota

Same here, I had an 85 4Runner with a 22R and it had an 02 sensor as well. I never could really understand why it needed one because it wasn`t fuel injected, but it was there.

Challenger

Well I guess there's a method to the madness so I'll go get a new one.

slow-mo

Hello all yotatatechers, new member here, but not new to my 1987 pickup 2WD. I've owned it since day one. I didn't see an area for newbies to post introductions so I thought I'd first get that out of the way.

The 22R California models, like mine & I'm assuming Challenger's since the location is Norcal (northern California), have a oxygen sensor for the purpose of emission control. The carburetor in the California model is a feedback carburetor type. That much is stated in the factory service manual. However, the computer only controls, or alters, the air side of the mixture, not the fuel side. The fuel side is fixed via the carburetor and it's actions. edit to add: I should state that there is one electrical devise on the carburetor that does control fuel, but that's a different story than this one. When the o2 sensor reads an out of spec reading (rich) it will do 2 things at the same time. One, the computer will activate the EBCV (Electronic Bleed Control Valve) and also activate the EACV (Electronic Air Control Valve), a.k.a. Air Suction. Both operate at the same time to correct the air fuel imbalance. The EBCV introduces air into the carburetor prior to combustion to lean out the mixture and the Air Suction introduces air into the exhaust, after combustion, to allow the rich fuel mixture to burn more completely prior the the catalytic converter.

If you like some interesting reading, all of this information can be found in the FSM under Emission Control System.

nordicwargod

Excellent description slow-mo. I know this is an old post I'm bring back from the dead!
I'm putting my 87 back together after rebuilding the engine and have been researching these exact same things. If you are going to use your stock carb and you don't have the above equipment mentioned you are probably going to run into problems with running issues and bad fuel mileage. In open loop the carb is running rich. It does this by default. The o2 sensor gives it the signal after the engine warms up to adjust the mixture by the above methods.
In a nutshell if your carb is running too rich you kiss your converter goodbye in short order and if its running too lean you will damage your exhaust valves and maybe cause your headgasket to fail.
If anyone tells you that you can remove all the emissions equipment and your carb will work fine is either full of cra#, or someone who has really put time into learning exactly how this system works and has made proper adjustments.
I would not know how to fool the carb into running right unless you have the 02 and other stuff.

user 82300

My 84 4Runner California model 22R has an O2 sensor on the exhaust manifold and a catalytic temp sensor on the cat. It depends on if your California, Federal, or Canada emissions vehicle. Took me few months to find the cat temp sensor too. It's just an EGT probe after getting an old service manual lol.

nordicwargod

Interesting. I've been looking at my 85 fsm and I don't see a cat temp sensor. I don't have one on my 87 either. There are temp sensors that turn on the egr, the eacv [the air injection before o2 sensor in the exhaust], and the all important outer vent control valve. But nothing to the cat.
In my opinion this california system system WITH the 02 sensor is much simpler than the federal/canada system with the belt driven air pump. It may be more efficient too!
Thinking of getting an air/fuel mixture gauge to see how the carb switches from rich to lean as I'm driving.
Hated this emissions stuff when I was younger but now I can see how it can actually help mileage and longevity of the engine.
If anyone has a link that describes what is happening with each system of this particular period of toyota engines please post it.

user 82300

85 won't have the cat temp sensor. And my 84 has the belt driven air pump with the air injection pipe going to exhaust manifold etc. the cat temp sensor on the cat seems to be and 84 and older system. When I switched from an oem manifold to a header the 02 sensor was relocated from manifold to bottom of down pipe. Doesn't seem to make a difference in fuel/air readings etc