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FZJ80 O2 sensor Replacement (1 Viewer)
- Thread starter CardonCruiser
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14ft/lb
- Joined
- Jul 20, 2004
- Threads
- 274
- Messages
- 23,205
- Location
- Chandler, AZ
- Website
- www.tontorecreationalliance.org
Just did this. Those Irwin bolt extractors are magical. Mine look like they were about done.
I don't but if your in a jam. I just replaced mine with stock nuts and a gasket from the help section at O'reilys.
Used a 1/4 ratchet and one hand snugged them.
My exhaust came back from Tellico in shambles. Broke rear muffler hanger by passenger wheel well and upstream o2 sensor nuts disintegrated. The muffler hanger broke first. I think the vibration of the tail pipe on the frame disintegrated the nuts after that. The nuts were badly rusted.
Campers and hikers love you when roll into a campsite with tuned exhaust note of the upstream o2 sensor blown out of the mount hole. I made the trip back across i40 with the o2 sensor held in place with SS wire.
Used a 1/4 ratchet and one hand snugged them.
My exhaust came back from Tellico in shambles. Broke rear muffler hanger by passenger wheel well and upstream o2 sensor nuts disintegrated. The muffler hanger broke first. I think the vibration of the tail pipe on the frame disintegrated the nuts after that. The nuts were badly rusted.
Campers and hikers love you when roll into a campsite with tuned exhaust note of the upstream o2 sensor blown out of the mount hole. I made the trip back across i40 with the o2 sensor held in place with SS wire.
Hey guys, I know this thread is about 2 years old now but I thought Id try to ask some questions anyways poised in bold at the bottom regarding o2 sensor voltage readings on my 1994 80 series with 1FZ-FE engine (ie 2 o2 sensors pre cat)...
So In the past 6 months now my CEL has being intermittently coming on (3 times now) indicating codes 21 or 28. Each time after the CEL turns on, I have inspected the O2 sensors and measured their resistance and they are within spec (ie 5ohms). When resetting the CEL codes by pulling the EFI fuse I than have performed the tests specified in the FSM to check if the problems associated with code21/code 28 are still there (see image below). Each time after I perform these Diagnostics the CEL does not come back on indicating the the sensors are fine (I guess) although I feel I probably haven't solved the problem bec after all the only thing I did was unplug it, measure resistance and clean it.
After repeating this 2 times the third time the CEL came on with code 21 I finally decided I need to probe the O2 sensor voltages to see if they are within spec. This is the part where I get confused. In following the FSM's directions to check the o2 sensor voltages I used a single channel scope (same results from dc multimeter) so i could see the live waveforms. to read the voltages I connected my scope to terminals VF1 (o2 sensor voltage signal) and E1(ground). After warming up the engine the manual says to short TE1 and E1. at this point one is supposed to maintain 2500rpms for 2min and observe voltages readings (see waveform data below). according to the FSM if you see 8 or more fluctuations in 10 seconds the sensor is within spec and that is all the information they give you. What Im confused about is that the manual never states what the min and max voltages should be or what the shape of the waveform should be for these voltage fluctuations. Somewhere I read the waveform should be a square wave and that is not what I am observing.
I am observing a kinda triangular like voltage spikes fluctuating about 8 times in 10 seconds with Vmax=4.29V and Vmin=-2.59V which given the limited info the FSM provides would suggest they are operating fine. Also I see the voltage fluctuation disappear when I decrease the rpms which I believe to be the o2 sensors responding to the changing exhaust conditions as they should be.
My question: Are these triangular like waveforms normal or are they indicating I need to replace the O2 sensors? Does shorting TE1-E1 change or amplify the o2 sensor signals?
Below is an image of the voltage readings on one of the sensors. Both sensors voltages look identical.
Any help would be greatly appreciated. My car runs like a dream currently but Im still suspicious that I may need new O2 sensors but wanted to see what others thought. I wonder if my issue is related to vacuum lines. Also, although currently I have no CEL on, I believe with time I will get a code 21 and or 28. BTWs This vehicle has already had the O2 sensor recall installed in 95 so toyota wont help me out with this one! Also I do live in California so am worried about passing emissions tests
So In the past 6 months now my CEL has being intermittently coming on (3 times now) indicating codes 21 or 28. Each time after the CEL turns on, I have inspected the O2 sensors and measured their resistance and they are within spec (ie 5ohms). When resetting the CEL codes by pulling the EFI fuse I than have performed the tests specified in the FSM to check if the problems associated with code21/code 28 are still there (see image below). Each time after I perform these Diagnostics the CEL does not come back on indicating the the sensors are fine (I guess) although I feel I probably haven't solved the problem bec after all the only thing I did was unplug it, measure resistance and clean it.
After repeating this 2 times the third time the CEL came on with code 21 I finally decided I need to probe the O2 sensor voltages to see if they are within spec. This is the part where I get confused. In following the FSM's directions to check the o2 sensor voltages I used a single channel scope (same results from dc multimeter) so i could see the live waveforms. to read the voltages I connected my scope to terminals VF1 (o2 sensor voltage signal) and E1(ground). After warming up the engine the manual says to short TE1 and E1. at this point one is supposed to maintain 2500rpms for 2min and observe voltages readings (see waveform data below). according to the FSM if you see 8 or more fluctuations in 10 seconds the sensor is within spec and that is all the information they give you. What Im confused about is that the manual never states what the min and max voltages should be or what the shape of the waveform should be for these voltage fluctuations. Somewhere I read the waveform should be a square wave and that is not what I am observing.
I am observing a kinda triangular like voltage spikes fluctuating about 8 times in 10 seconds with Vmax=4.29V and Vmin=-2.59V which given the limited info the FSM provides would suggest they are operating fine. Also I see the voltage fluctuation disappear when I decrease the rpms which I believe to be the o2 sensors responding to the changing exhaust conditions as they should be.
My question: Are these triangular like waveforms normal or are they indicating I need to replace the O2 sensors? Does shorting TE1-E1 change or amplify the o2 sensor signals?
Below is an image of the voltage readings on one of the sensors. Both sensors voltages look identical.
Any help would be greatly appreciated. My car runs like a dream currently but Im still suspicious that I may need new O2 sensors but wanted to see what others thought. I wonder if my issue is related to vacuum lines. Also, although currently I have no CEL on, I believe with time I will get a code 21 and or 28. BTWs This vehicle has already had the O2 sensor recall installed in 95 so toyota wont help me out with this one! Also I do live in California so am worried about passing emissions tests
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ppc
M Go Blue
First connecting between VF1 and E1 is only testing the ECM output related to the first O2 sensor, not the output of the sensor itself. Have you also tested VF2 to E1 and gotten the same results? The FSM table on page EG316 calls out to check the number of pulses with the TE1 and E1 shorted which places the ECM in base mode. Voltage is not measured at that step. The second step is when there are less than 8 pulses instructing you to remove the TE1 and E1 connection maintaining the 2500 RPM, then measure VF1/VF2 voltages. The manual is a bit fuzzy but my interpretation that at that point the ECM has determined a lean or rich condition is occuring. At that point the voltage measurements of VF1/VF2 measurements guide you through the rest of the tree.
If you really want to look at performance and wave forms of the O2 sensors you want to connect to OX1 or OX2. The 21 and 28 codes get set when the amplitude of the voltages drop to between 0.35 to 0.70 volts continuously for 60 seconds or more while vehicle speed is below 60 MPH and over 1700 RPM.
If you really want to look at performance and wave forms of the O2 sensors you want to connect to OX1 or OX2. The 21 and 28 codes get set when the amplitude of the voltages drop to between 0.35 to 0.70 volts continuously for 60 seconds or more while vehicle speed is below 60 MPH and over 1700 RPM.
Thanks for the clarification, these things do seem a bit fuzzy sometimes ... VF1 is ECU output, looking again at the schematic for some reason its only just sinking in haha and yes as you stated Im interested in measuring the actual O2 sensor which would be OX1-E1 and OX2-E2 I guess. Yes both VF1-E1 and VF2-E2 have the same characteristic as the waveform I showed and in my case Im observing 8 or more fluctuations in 10seconds (with TE1-E1 shorted) while maintaining 2500rpms so this leads me through the tree to normal operation I believe. At this point I'm suspicious my issue may be coming from the o2 sensors wiring. Going forward I want to check the o2 sensor waveform (OX1/OX2-E1) and make sure all of the wires leading to the O2 sensor are good (good=low resistance). Ill post again with updates
FSM EG316 for reminder :
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Have you had any luck finding your issue ? I just pulled both 21 and 28 codes on mine . I ordered two new o2 sensors and figured at 145k it could hurt to start fresh . They were only 35$ for Densos from rockauto . I am hoping this clears up some of random engine issues . Have you checked you spark plugs to see what they look like ? Running lean or rich ?
So in my situation I pulled the EFI fuse to reset the CEL and the codes went away for a few months and all the diagnostic tests I do it passes. Its maybe noteworthy to note that I only drive about 10 miles a day to and from work on average. BUT, the first long road trip I went on (6hrs drive up north to Big Sur CA) sure enough eventually code 21 came back on. This weekend if I have the time I want to check the cables that supply the voltage to the heaters, ill post results once I check that.
Hi all,
I'm getting code 28, meaning I'm not getting the No. 2 O2 sensor signal...
I've never done this job... Is No 2 right after the cats? And if so, where is the other one?
I feel like a noob
What year truck are you working on?Hi all,
I'm getting code 28, meaning I'm not getting the No. 2 O2 sensor signal...
I've never done this job... Is No 2 right after the cats? And if so, where is the other one?
I feel like a noob
I'm on a 1994 usa model
From the 1994 FSM diagram:
If you don't have a FSM, go to the Resources tab above and download one.
Ahhh thank you. I only have the Haynes.... I get it... Two exhausts, #1 #2...
I was thinking they were in serial, not parallel...
Ok thanks Bilt!
Replacing both my O2 sensors on my 94 and seems OEM and NTK replacements are unobtanium. Any feedback if Denso 234-4520 are compatible? Thank you.
Lextronix
SILVER Star
You can use the Denso ones for the 95-97s if you swap the connectors. I think I'll give this a try on my next set.
Here is NLXTACY's great guide:
Repurposing 95-97 Oxygen Sensors for 93-94 1FZs - https://forum.ih8mud.com/threads/repurposing-95-97-oxygen-sensors-for-93-94-1fzs.1178425/
The NTK ones pop up erratically on RockAuto. I set a notification and I think they came in stock after a month or two.
Here is NLXTACY's great guide:
Repurposing 95-97 Oxygen Sensors for 93-94 1FZs - https://forum.ih8mud.com/threads/repurposing-95-97-oxygen-sensors-for-93-94-1fzs.1178425/
The NTK ones pop up erratically on RockAuto. I set a notification and I think they came in stock after a month or two.
Thank you that's the thread and info I needed. I wasn't sure if the NTK were forever gone or just running short like everything else right now. All the molex connectors on my rig are really brittle so I'm hesitant to attempt surgery on a set of Denso sensors. Although if desperate guess I could do away with the connectors and just butt slice the wires.
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I had to remove the stud and then after stud out removed the bolt.
