FZJ80 Failed CO Emissions and Code 25

[FZJFirefly]

Maybe I am misunderstanding what you did --if what you did was install a 95-97 O2 sensor on a 94 --- but in my opinion you screwed up here. The 95-97 O2 sensor is not compatible with the 93/94 computer, and changing the connector does not fix it. The issue is not just that the connectors are different -- it is the ohm values the sensor provides during operation.

So maybe I misunderstand, but if it were my I would source the correct 93/94 O2 Sensor (and switch back to the old style connector).

Preferably OEM Toyota if you can find it. The OEM Toyota sensor you can use for both locations on the 93/94 is 89465-69115.

And while you are at it get two of those sensors.

You’re right with the values. Just bought a multimeter and tested the ohm value of the new o2 sensor at 13.5ohms when the fsm states 5-6.5ohms. So I’m going to order those o2 sensors and hope that fixes the majority of my issues

 

[FZJFirefly]

I can't help you. The Cats are a big expensive project and they are also pretty robust. The best test I know is an infrared thermometer. Check the from of a hot cat and the back, the back needs to be something on the order of 100 degrees hotter. If the front and back are the same temp, you have a Cat issue. I simply run too many old cars with original Cats to focus on them as a primary fault, unless they throw a unique code. I had a P0425 on my wife's Lexus that I ignored right up to the test. I fixed an exhaust leak in the flex pipe a foot away and after a week or so the P0425 disappeared.

There is a ton of info on here about the IAC and in the FSM. I never touched mine beyond confirming the resistance on the pin outs.

I do not think adjusting the IAC is all that difficult, but I recall taking it apart carries risks.

I tested the cats with a heat gun after that most recent fail and it was about exactly 100 degrees hotter out of the back then exhaust going into the cats

 

[OffRoadScott]

You’re right with the values. Just bought a multimeter and tested the ohm value of the new o2 sensor at 13.5ohms when the fsm states 5-6.5ohms. So I’m going to order those o2 sensors and hope that fixes the majority of my issues

I do not recall if I have replied to this post about the OHM resistance on your O2 sensors. But I was having very similar issues and checked the VAF and it was GTG, then checked the O2 sensors the resistance was way off like yours were. I replaced mine with Bosch O2 sensors, against the recommendation of others on this forum but Bosch has been around for years. I have had to do 2 emissions test here in AZ and pass every time now.

 

[BTLSHP]

I do not recall if I have replied to this post about the OHM resistance on your O2 sensors. But I was having very similar issues and checked the VAF and it was GTG, then checked the O2 sensors the resistance was way off like yours were. I replaced mine with Bosch O2 sensors, against the recommendation of others on this forum but Bosch has been around for years. I have had to do 2 emissions test here in AZ and pass every time now.

I read your Bosch Sensor post with great interest and fantasy's about what I could do with the money saved. I chickened out.

I wonder if the recent court decisions rejecting the 10% tariffs means we are back to the old ways with Partsouq and Japan4x4?

 

[BTLSHP]

I tested the cats with a heat gun after that most recent fail and it was about exactly 100 degrees hotter out of the back then exhaust going into the cats

So, I think you can tick those off of your risk list for now. I have no idea how mine would have been replaced. The flanges and bolts were one. If you are in the FSM near the O2 Sensor pages is the test procedure for the VAF. I went no further than confirm the resistance. The next step would be to gently clean the vanes and their pivots with air. Not me.

Good luck

 

[OffRoadScott]

I read your Bosch Sensor post with great interest and fantasy's about what I could do with the money saved. I chickened out.

I wonder if the recent court decisions rejecting the 10% tariffs means we are back to the old ways with Partsouq and Japan4x4?

Just checked Amayama and they are including the fees when you proceed to the cart to check out.

 

[FZJFirefly]

Okay well now I’m just confused. It got better than the purple one but it’s still worse than the yellow one. Also I noticed they turned overdrive off when testing it would that cause it to have more emissions due to higher rpm or is it negligible?

O2 sensors helped the idle a lot but still feels a little low as well.

Is it time to bite the bullet and replace cats?

 

[BTLSHP]

I would not jump into cats. You have a decent temp differential there based on my '94 a year ago. You have something wrong with your idle, any signs of a fuel pressure issue/injector leak?

What my daughter did was go back for her "free" test and they directed her to the State help lab. The guy there was incredibly helpful.

Sorry you are still in this mess. Ours had been test free for 6 years before getting to CO. I was biting my nails.

Sorry I do not Know how to rotate this. It is one of our failed tests. Note our CO line on the right side of the graph was up and down, where yours was a flat line. Curious.