I am going to replace my O2s sensors on my 94 FZJ80 tomorrow. On the 94 the are side by side under the passengers feet before the cats. I have them sprayed down with P blaster as we speak. Hopefully that will help some. the main thing is that there does not look to be much room to work with. I guess i could get a small wrench on it. Is there anything i am supposed to remove or move to get better access to them? Any advice to help them break free?
O2 sensor removal advice
- Thread starter rc51kid
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
I used an air chisel in a way that splits and loosens the nut while you hit it.
You may not have room, but it is easy if you do.
Plan on new nuts.
You may not have room, but it is easy if you do.
Plan on new nuts.
Just curious, how often should we change the O2 sensor?
Pretty sure I'm on the original ones at almost 200k. I generally like to not fix things if it's not broken but I don't know what would happen if O2 sensor dies besides CEL.
Pretty sure I'm on the original ones at almost 200k. I generally like to not fix things if it's not broken but I don't know what would happen if O2 sensor dies besides CEL.
You should replace them when they are clearly no longer working properly.
If your truck seems to be running properly, don't fix what aint broke?
What happens when o2 sensor goes out of spec is your air/fuel mixture becomes too rich or too lean. Does your exhaust still smell like gasoline when the engine is up to temperature? Does your exhaust manifold glow in the dark? No? You are probably ok, provided you still pass emissions sniffer tests and all.
A friend of mine got the outer-most o2 sensor nut off with a very small pipe wrench.
Removing the heat shield attached to the body right there helped. A set of 'gear-wrench' box-end ratchets w/ the floppy heads made that easy.
Getting the inner one off involved my dremel and a hammer and chisel.
After burning many hours finagling the inner ones, I handed my rig over to the best mechanic in the valley. I purchased and attempted to use a variety of nut-removal tools which proved to be utterly impotent.
He said he soaked them down with penetrating oil, let it sit over night, and then "cursed at them and shook big sticks at them" -- I imagine it's way easier if you have a lift.
If your truck seems to be running properly, don't fix what aint broke?
What happens when o2 sensor goes out of spec is your air/fuel mixture becomes too rich or too lean. Does your exhaust still smell like gasoline when the engine is up to temperature? Does your exhaust manifold glow in the dark? No? You are probably ok, provided you still pass emissions sniffer tests and all.
A friend of mine got the outer-most o2 sensor nut off with a very small pipe wrench.
Removing the heat shield attached to the body right there helped. A set of 'gear-wrench' box-end ratchets w/ the floppy heads made that easy.
Getting the inner one off involved my dremel and a hammer and chisel.
After burning many hours finagling the inner ones, I handed my rig over to the best mechanic in the valley. I purchased and attempted to use a variety of nut-removal tools which proved to be utterly impotent.
He said he soaked them down with penetrating oil, let it sit over night, and then "cursed at them and shook big sticks at them" -- I imagine it's way easier if you have a lift.
- Thread starter
- #5
Thanks for the advice. I just wanted to give a update. I Sprayed them all down with PB blaster the night before. I guess they it was about 16 hours or so that it was left to penetrate. I then hit each nut with some propane. I made a little heat shield with some folded up aluminum foil and also had a fire extinguisher standing by. I hit each bolt for about 60 seconds with the propane. The hardest part trying to fit a wrench or small socket on them Mostly i took my time and made sure that i had the socket or box end of the wrench on the nut really straight in order to get full contact and not strip the nut. The all broke free with a nice clean "snap". One or two of them took some real finagling to get a tool positioned correctly and straight. But got them all off and the new sensors installed. The sad part is that with the new sensors i still failed emissions. I think my old ones were fine.
If you still had flats on your nuts that you could get a wrench on, you are very lucky!
Seriously. Mine looked like meteorites!
Here's a shot of the 1st one to come off:
The best suggestion i heard at the time was to hammer a cheap 12-point 11mm socket onto them.
Couldn't get a hammer in there.
Thanks for the advice. I just wanted to give a update. I Sprayed them all down with PB blaster the night before. I guess they it was about 16 hours or so that it was left to penetrate. I then hit each nut with some propane. I made a little heat shield with some folded up aluminum foil and also had a fire extinguisher standing by. I hit each bolt for about 60 seconds with the propane. The hardest part trying to fit a wrench or small socket on them Mostly i took my time and made sure that i had the socket or box end of the wrench on the nut really straight in order to get full contact and not strip the nut. The all broke free with a nice clean "snap". One or two of them took some real finagling to get a tool positioned correctly and straight. But got them all off and the new sensors installed. The sad part is that with the new sensors i still failed emissions. I think my old ones were fine.
eh, maybe you can sell your lightly used pair? Get some copper-clad nuts to reinstall the old ones so they are easier to remove in the future? NAPA has the gaskets.
What were your emissions numbers? e.g. what part did you fail on? Do you have any codes? And, what else have you tried?
How long since basic tuneup stuff? e.g. cap, rotor, plugs, wires.
- Thread starter
- #9
I actually am leaving the new ones on and TRYING to sell the ones that came off. I failed on high CO, had a EGR code until i bypassed it then no codes, ran great. I ended up doing a full Toyota tune up kit and used the Toyota plug to bypass the EGR. I actually found a way around the emissions but that is another story. So for now i am leaving it alone.
- Thread starter
- #10
Seriously. Mine looked like meteorites!
Here's a shot of the 1st one to come off:
The best suggestion i heard at the time was to hammer a cheap 12-point 11mm socket onto them.
Couldn't get a hammer in there.
That does look nasty. The ones i took off looked 100x better than that. Just had the corned slightly rusted on only 2 of the nuts. I figured that was a bad sign that somone couldnt get them off. Now looking at yours i think tit might just be from instal and i bet they are not the original 20 year old O2s.
I had no problem replacing mine on my 94. I've lucked out with a truck that's been in Texas it's whole life (from what I can tell) and has no rust. I'd read all the problems and horror stories of demon 02 sensor nuts, but mine came right off after a night soaking in PB. My only issue now is I didn't go with stock sensor replacement and have an annoying power stall like symptom when the truck is cold. Plan to go back to stock one day soon, but my problem isn't worth the expense of new stock sensors.
Sent from my iPhone
Sent from my iPhone
The yota kit comes with new nuts and gaskets.
But stainless steel is only so stainless. Probably why VW uses copper plated nuts on exhaust parts.
I actually did mine in about 40 minutes, removed the plugs, fished the plugs up into the engine bay, removed the smog pump and pipes, then bolted my new o2 sensors right into the exhaust manifolds. Used the free'd up bolt holes from the smog pump (which wasn't working anyway) and used it for the mounting bracket I made for a York Onboard Air compressor oh..and there is a hose that runs to a small metal tube along the front of the engine, I just vacuum capped that.
I would really like to do this.
Unfortunately, I live in an emissions county, and the air injection (which works) is on the check list when i get my IM results.
I deleted the silencer for a 2nd battery tray, so i can *hear it work. Sadly, it does bupkis to lower actual emissions - which is why Colorado has gone to a grams-per-mile measurement rather than the usual % of total.
In my old fiat, the air injection nozzles are right next to the exhaust valves, where the injection of fresh air can and does cause some of the hydrocarbons to combust, because they are still glowing hot. The injection manifold is between the cams, and makes spark plug removal a pain.
The PAIR system on the 93-94 1FZ-FE is too far from the combustion chamber to do anything but dilute the exhaust gasses.
The irony is that since my Fiat is a '77, I can register it as a vintage vehicle and never have to worry about safety or IM again. $60 well spent.
But i have to keep the worthless PAIR system until i move to a non-emissions county or the rig turns 30 years old.
High CO means you are running rich, you need more O2 to burn the CO the rest of the way to CO2. You may be able to adjust your AFM or whatever it's called.
About copper nuts, I had a muffler that kept coming loose, an old exhaust guy put on copper nuts on and it didn't come loose anymore. Different rates of expansion he said
I am planning on replacing mine this weekend . I have some nut extractors in case things get dicey . Have any of you had to just slice the nut of with a nut breaker ? Also I am glad I don't live in a state that your vehicle has to pass emissions that sounds like a pain in the ass