FZJ80 Failed CO Emissions and Code 25

[FZJFirefly]

Hey Everyone!
Just bought a FZJ80 in Utah a few weeks ago with replaced cats. Trying to get emissions yesterday and it failed on CO GPM with 79.105 with a limit of 20. Replaced the distributor cap & rotor, spark plugs, spark plug wires, and replaced all the small vacuum lines with silicone ones. Tested today with 64.7612 CO GPM any one have any clue why its emissions of CO are so high when the truck has a code for continuous lean?

Thanks in advance!

EDIT: Wanted to add it’s a 1994 and the CEL Code 25 turns on and off as it feel likes and isn’t a constant code it also sometimes has a low idle at about 350-500rpm and other times it’s at about 550-700

EDIT #2: I’m calling the Code 25 fixed as since I’ve replaced all the small vacuum lines it’s been over 200 miles without it showing

 

[MileHigh80Guy]

Check your timing with a gun, could be a vacuum leak, exhaust between engine and O2. My wiring was FUBAR, could be something along the chain there or simply a bad O2. Toyota makes them again for OBD1 trucks, but check the FSM for the O2 wiring values and resistance readings.

 

[OffRoadScott]

Check the resistance on the O2 sensors. The FSM calls for 5.5 ohm.

 

[FZJFirefly]

Check your timing with a gun, could be a vacuum leak, exhaust between engine and O2. My wiring was FUBAR, could be something along the chain there or simply a bad O2. Toyota makes them again for OBD1 trucks, but check the FSM for the O2 wiring values and resistance readings.

Gotcha, I’ve already replaced the 1-3cyl O2 sensor with a new connector to the 95-97 sensor as my old o2 sensor had a pin corroded and broke off inside the connector. I’ll check the 4-6 one though. Also replacing the last of the vacuum lines I couldn’t get to as I bought more silicone lines

 

[MileHigh80Guy]

Quick and dirty, unplug the battery first, reset the code and then swap the O2 harness plug to the other one. See if the code follows.

Saw on your Rising suns post that you repinned the OBD2 ones, but these are the parts you need. Those posts were made when the stopped selling them and the other non oem market dried up.

There were 2 part numbers, same sensor, different length pigtail.
Now they have the same longer pigtail and one part number.

Oxygen Sensor #89465-69115 | Autoparts.toyota.com - https://autoparts.toyota.com/products/product/sensor-oxygen-8946569115

 

[FZJFirefly]

Quick and dirty, unplug the battery first, reset the code and then swap the O2 harness plug to the other one. See if the code follows.

Saw on your Rising suns post that you repinned the OBD2 ones, but these are the parts you need. Those posts were made when the stopped selling them and the other non oem market dried up.

There were 2 part numbers, same sensor, different length pigtail.
Now they have the same longer pigtail and one part number.

Oxygen Sensor #89465-69115 | Autoparts.toyota.com - https://autoparts.toyota.com/products/product/sensor-oxygen-8946569115

Oh good to know for my 4-6 one. However I didn’t just rewire I completely swapped the connector to the new style as the old one had a pin corroded into it. Also the code 25 stopped coming back after I replaced most of the small vacuum lines so I’m going to try an oil change and a few bottles of red heet next time I go and hope it makes a difference!

 

[discoverydave]

Oh good to know for my 4-6 one. However I didn’t just rewire I completely swapped the connector to the new style as the old one had a pin corroded into it. Also the code 25 stopped coming back after I replaced most of the small vacuum lines so I’m going to try an oil change and a few bottles of red heet next time I go and hope it makes a difference!

 

[BTLSHP]

Ugh, We had issues with our '94 after delivering it to my daughter. We went through a couple rounds of test and adjustment until we got an invite to a State run help facility. Justin the inspector vowed to stay with us until it passed and was super helpful. The lead code was not bad enough to trip the light. We had high CO values.

I had change the outboard sensor as part of the re-hab as the heater had gone out. I ignored the inboard sensor (but had a new one) because I could not reach the nuts and it still tested fine.

Long story short, changing the inboard sensor was enough to make it pass with flying colors. I will see if I can find the final

 

[BTLSHP]

Here is the final after the O2 Sensor change along with one of the failures. One of the early failures had the CO at 79.

 

[Brindleboxer]

Just an FYI, the 94 computer will auto clear codes once they establish the expected baseline again unlike the 95+ that retain the code for pulling and clearing after the fact. I had this issue when I first got my truck and would have a code pop (intermittent) but then when I went to pull the code it wouldn't be present. It was frustrating to say the least.

 

[sjpitts]

Gotcha, I’ve already replaced the 1-3cyl O2 sensor with a new connector to the 95-97 sensor as my old o2 sensor had a pin corroded and broke off inside the connector. I’ll check the 4-6 one though. Also replacing the last of the vacuum lines I couldn’t get to as I bought more silicone lines

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.

 

[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.

Oh I didn’t know that I assumed it was fine as I saw others had passed with them before and considering it cleared my code 21 I’ll definitely look into those sensor and see if I can find another connector for the one I swapped

 

[FZJFirefly]

Okay so it somehow has gotten worse.

I’ve yet to replace that O2 sensor as my cruiser decided to blow some seals in the front so while I was replacing that I adjusted timing and replaced a bunch of the vacuum lines under the intake manifold. So I decided to go and have a test after putting 2 bottles of red heet in the tank. Any thoughts on how this would be the worst test? And code 25 (Continuously Lean) is back for some reason as well

 

[BTLSHP]

So, we had 3 tests before the invite to see Justin the super tech near Westminster. My inboard sensor was causing no light and it seemed ok per the FSM during my rehab activity. I replaced the outboard sensor due to a heater failure and had a spare new Toyota sensor acquired from Japan4x4. The inboard sensor seemed ok per the FSM and since I could not get at it, I left it be.

In the rehab process I had done a pretty thorough job of chasing down Cel 71, I had 25/26 sporadically and then just before the trip out to Denver I saw 25 alone. I can't recall what I did, but by this time I would have followed the FSM. It was not showing a code when it was inspected nor on the entire 1,700 mile trip out.

In #8 post you will see Justin notes a stored lean code (26) and he initially pointed to the O2 sensors but found they were working at full range which did not make sense to him. He saw the new and old sensor and suggested that before anything else we replace the old sensor (7 years, 35k miles). Apparently, this was what Toyota intended per the FSM.

The variability or our results prior to the PASS was pretty dramatic. Part of it was she followed a co-workers thoughts and tried 10 gallons of e-85.

Justin was about as helpful as you could ever ask for. I believe he is near Westminster.

89465-69115 is the correct part and you need 2. My lexus dealer has them for $141 each, I think I paid 195 for the pair in Japan.

Good Luck

 

[FZJFirefly]

Just replaced that other sensor with a 95+ as I didn’t want to spend that much for one sensor which was a mistake in my part but this new sensor has made it the worst test yet I’m going to replace both of the sensors with those oem ones but if this doesn’t fix it are we at cats?

Purple is the one from this morning and I also had a code come back haven’t checked it but I assume it’s code 25

 

[BTLSHP]

Again, 2 new correct O2 Sensors was all we needed to easily get through. I am not smart enough to know if the 95+ sensors are electrically compatible with the '93-94 sensors. I think prior to replacing the inboard our results were more variable but some of that was the E-85 issue, but that impacted one test.

Justin, the CO State Tech, seemed to be more concerned about the VAF and thought failed cats were a possibility but he would not reach that conclusion until the O2 Sensors were both new (we had no errors from the 7 year old inboard sensor) and the VAF had been ruled out. The VAF tested fine electrically per the FSM, but he thought if there was an issue it would be in how quickly the vanes closed when the foot came off of the gas. In the end, we did not touch the VAF.

I hope this helps. It was a downer to have it fail without an active code after all the work we had done to the car before driving out there.

 

[FZJFirefly]

Again, 2 new correct O2 Sensors was all we needed to easily get through. I am not smart enough to know if the 95+ sensors are electrically compatible with the '93-94 sensors. I think prior to replacing the inboard our results were more variable but some of that was the E-85 issue, but that impacted one test.

Justin, the CO State Tech, seemed to be more concerned about the VAF and thought failed cats were a possibility but he would not reach that conclusion until the O2 Sensors were both new (we had no errors from the 7 year old inboard sensor) and the VAF had been ruled out. The VAF tested fine electrically per the FSM, but he thought if there was an issue it would be in how quickly the vanes closed when the foot came off of the gas. In the end, we did not touch the VAF.

I hope this helps. It was a downer to have it fail without an active code after all the work we had done to the car before driving out there.

Yeah it’s just hard for me to want to spend ~$350 without knowing if those will even fix anything. Does anyone know what pins in the obd1 port you have to jump to read the o2 sensors voltages?

 

[BTLSHP]

It begins on page EG-315/16 of the FSM positive to VF1 or VF2 Negative to E1. I think the test is best run on an older analog meter as you are counting swings in a 10 second period as well as testing voltage. The "older" O2 Sensor that proved to be the culprit passed both this and the emission tech's testing. Meaning it only failed to perform under certain conditions, I believe.

O2 sensors are free compared to new Cats

 

[FZJFirefly]

It begins on page EG-315/16 of the FSM positive to VF1 or VF2 Negative to E1. I think the test is best run on an older analog meter as you are counting swings in a 10 second period as well as testing voltage. The "older" O2 Sensor that proved to be the culprit passed both this and the emission tech's testing. Meaning it only failed to perform under certain conditions, I believe.

O2 sensors are free compared to new Cats

That’s true but considering the idle is wrong and I have a code I’m going to hope the cats aren’t the problem and it’s either o2 sensors or a random other issue

 

[BTLSHP]

That’s true but considering the idle is wrong and I have a code I’m going to hope the cats aren’t the problem and it’s either o2 sensors or a random other issue

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.