Aztom

Hey everyone I recently pulled out my 94 Toyota it's been sitting about 2 years started right up had a code for rpm signal which was igniter wiring got that fixed and o2 sensor code 21 of coarse it didn't run well didn't rev up and was running really rich. I drained the gas new plugs new fuel filter and pulled the o2 figured I'd try cleaning it since the stores were closed it was really black. But either way most of what I read the code come on after a while where mine is instant I can unhook the battery re hook it up just turn the key on and the code is there so is the o2 really bad and messed up or is there another problem
22re 5sp 2wd

scope103

Code 21 is when there is an open/short in the heater circuit of the sensor. So it will not go into closed loop as quickly. So it is probably not the cause of your running rich.

But you can test the sensor: http://web.archive.org/web/201503060...42oxygense.pdf

Aztom

thank you sir I will check that. My main question is more of can the o2 go bad from sitting because I didn't have that code when I parked it and 2 if the o2 is bad can the o2 itself cause it to read open/short or is there some wiring problem. Thanks for the help

abecedarian

Anything is possible.

Corrosion of connectors is possible.

Aztom

thanks scope for correct answer. Threw a new o2 in still had cel for 21 tried another ecu and it threw 21 and 25 must be for one with 2 o2 sensors went back to the first one and had no continuity on one of the heater wires to the ecu

helidriver

I replaced my O2 (22REC 1987 type) after getting #5 code. New O2 sensor.... still getting #5 code....

Aztom

whats code 5? I did fix mine. I believe 87 have a single wire o2 sensor. But I'm not sure on that. I had a 4 wire o2 sensor and one of the wires had no continuity in it like it was cut somewhere. It wasn't but I had to run a new wire

helidriver

So was your problem in the harness wire from the O2 connector to the ECU? I have the single wire to the connector to the harness. Not sure how many relays/fuse blocks it goes through to get back to the ecm? Thats what I want to check, the wires/harness to the ECM, because I changed brand new sensor (didn't test the old one figured it was 10+ years old and ready either way).

Hey, side note...... If I shake the ingnitor coil?......? Should I hear fluid in it???!?

Also, is there vacuum on the lower end in the crankcase? This whole thing is trying to figure out why I have a misfire situation and throwing a Code 5, O2 circuit/sensor/ECM. If my oil dipstick rubber seal is dry like a rock and shrunk could it be a vacuum leak source/"un-metered air source to cause a rich ratio and thus causing the O2 code trigger??? Top top end at the intake and at the brake booster vacuum is 17.5 steady, no leaks up top.

Aztom

no idea I ran a whole new wire didn't seem like it went through any fuses or relays. Just straight to the ecu.
Yes there is fluid in the coil
there maybe a very slight amount of vacuum at the bottom of the crankcase from the pcv however that wouldn't cause it to throw any codes

87-4runner

You might try the 82 Supra AFM if, you can find one. They're a little pricey but with your mods it might be a help with air and fuel ratios...
the 82 is plug and play