BeaverTV Posted August 26, 2014 Share Posted August 26, 2014 I have a '95 Pathfinder - has been running rich, then last week, during the drive home from Seattle, kept cutting out, dying, and running like on 4 cylinders (if that) - got on here to this forum & figured that it would be a good thing to replace the o2 sensor -- and also checked with Autozone diagnostics (they came up with the same idea) -- thcar also has over 292,000 miles on it. My boyfriend (not a mechanic- a musician) is trying to get the old sensor out -- but it seems to be heat welded on - the one located by the cat (btw it is a 4-wheel drive auto) PLEASE -- i need help -- we are stuck here with no wheels without our Pathy working -- .. . . . what kind of tools can we use to get that dang old sensor out . . . used a lot of liquid wrench so far . . . and I am hearing a lot of banging from the wrench . . . . . ..HELP!!!! (Please) Link to comment Share on other sites More sharing options...
Nefarious Posted August 26, 2014 Share Posted August 26, 2014 (edited) Be careful when doing this but it works for me every time. You will need heat. I use a MPS gas torch but a propane torch will work as well. Both can be had at any larger hardware store for about 15-20$. Its just a small torch with a bottle the size of one you would use for a camping stove. Heat up the old o2 sensor for a good 3-4 minutes and then use a wrench to crack it. Any fitting or sensor that threads into the exhaust system generally gets seized from the rust and constant heat cycles. You will need some torque on the wrench but with heat it will crack loose. If its still stubborn, more heat. Ive had to bake some parts for 10 mins before the expansion broke the seize but it will work. If you need more torque on the wrench, you can use two wrenches of similar size end to end. It works well as it doubles your torque but it can be dangerous if you slip so be careful and do at your own risk. Look up on Google for a picture but it will be an easy thing to find how to slip one into the other. Good luck! Edited August 26, 2014 by Nefarious Link to comment Share on other sites More sharing options...
adamzan Posted August 26, 2014 Share Posted August 26, 2014 Another way, that has worked everytime on a pathfinder for me, is to let the truck run for a bit to let the pipes get warm. Be careful not to burn yourself. But it will work if you don't have a torch, or if funds are tight. Link to comment Share on other sites More sharing options...
Precise1 Posted August 26, 2014 Share Posted August 26, 2014 Some of all of the above... When cold, spray it with a penetrant (PB blaster, liquid wrench, NOT WD-40) a few times over a day or two and see of it comes loose with a proper wrench. If not, run it like Adam says, let it cool enough so you arent going to burn yourself and try to break it free with a good fitting wrench (pipe wrench might be appropriate if it is well rusted). Have someone hold the pipe still if possible, this will increase the appliable torque. If that doesn't work, use a propane (or MAAP) torch to heat the exhaust/bung area, not the O2 sensor. Heating expands metal and you want the fitting to expand, not the sensor within it. Try to get it loose with the wrench again, and if that doesn't work, heat it up again and then use one of those 'dust off' spray cans INVERTED to cool the sensor around the thread base, then try again. If none of that works, report back and we'll probably recommend using a sawzall or angle grinder with cut off blade... B Link to comment Share on other sites More sharing options...
Nefarious Posted August 27, 2014 Share Posted August 27, 2014 (edited) My bad I should have been more clear to heat up the bung and not the sensor. Joys of typing on a cell phone! BTW, I don't know if it's a Canadian thing or not but whenever I've seen maap gas, it's been listed as MPS gas not MAAP. So it may differ in your area. Edited August 27, 2014 by Nefarious Link to comment Share on other sites More sharing options...
Precise1 Posted August 27, 2014 Share Posted August 27, 2014 No worries, that is all I know it as but apparently the product changes and the name doesn't. http://en.wikipedia.org/wiki/MAPP_gas It is probably the same or equivalent, depending on local names/laws. I just used MAAP as that is probably what he will see in the hardware store in Warshington... B Link to comment Share on other sites More sharing options...
k9sar Posted August 27, 2014 Share Posted August 27, 2014 Mine took quite a bit of PB Blaster and driving to/from work. A few days of that then a wrench with a pipe slipped over the end for leverage broke it loose. Link to comment Share on other sites More sharing options...
tmoore4512 Posted August 27, 2014 Share Posted August 27, 2014 All great suggestions...What I did was a combination of Penetrol (Schaefers Oil Products) which is essentially the same things as PB Blaster, and heat.Had to use a pair of channel locks to break it loose the first time around.Second replacement I had purchased a O2 sensor socket from a local parts house, it was about $20 but made it that much easier.Still had to use penetrant and heat however.I would suggest using an anti seize that is designed for O2 sensors or high heat as mentioned... Link to comment Share on other sites More sharing options...
BeaverTV Posted August 27, 2014 Author Share Posted August 27, 2014 Thank you for the replies -- we did get it off - and it was the liquid wrench over a couple days and wrenching and banging on it -- new one in -- it is running - drove around the block - and it started to stall again ...... any suggestions as to what I should look at first? fuel filter maybe? car has just under 300,000 -- Still looking for a little more help -- don't want to take it too far from home..... Link to comment Share on other sites More sharing options...
k9sar Posted August 27, 2014 Share Posted August 27, 2014 and how the hell does Autozone Diagnostics come up with replacing the O2 sensor on a 95? I doubt they have the ability to read any codes from a pre-2000 vehicle. Stalling could be a number of things... dirty MAF, IACV, disty cap, ... More diagnostics would help... First of all, is the check engine light coming on? Is it stalling on hard deceleration only or on acceleration only? Any repeatable characteristics would be helpful in narrowing down the problem. Sorry you are still having problems with it. Link to comment Share on other sites More sharing options...
k9sar Posted August 27, 2014 Share Posted August 27, 2014 also, with the hood open and engine running, wiggle the connector and/or wire on top of the MAF. That is a known weak area that can cause crappy running. Hint, wiggling the connection should NOT have an effect on the engine running. Link to comment Share on other sites More sharing options...
Nefarious Posted August 27, 2014 Share Posted August 27, 2014 Yeah its definitely time to run the ecu diagnostics codes. Ecu in the pathfinder has self diagnostics on mode 3 of ecu functionality. There is a great guide on how to check the codes on this forum in the garage section. The ecu is located under the passenger seat. please report back once you have completed the diagnostic and report on any possible error codes, then we can help you a little easier. Code 55 means everything is okay, anything else is a problem. Link to comment Share on other sites More sharing options...
Precise1 Posted August 27, 2014 Share Posted August 27, 2014 x3 on checking the ECU for stored codes, and if not, then it is sensor check time! Go to the Garage section and download a FSM from the pinned thread. in the EC section there will be a trouble shooting section based on symptoms (ie. stalling hot, stalling cold, stumbling, etc) and follow the diagnostic proceedure. Odds are it is what a mechanic would do... B Link to comment Share on other sites More sharing options...
ebayfish Posted August 28, 2014 Share Posted August 28, 2014 Definitely check the codes. Its easy to do & you can do it yourself. If you don't know when the fuel filter was changed last, its definitely a great $15 investment. Mine started hesitating & I think it was a combination of spark & clogged EGR(only code that was thrown). I ran 2/3 a bottle SeaFoam in the crankcase for a day before an oil change, then flushed the rest of the bottle through the vacuum lines & smoked out the neighborhood. I sprayed out the throttle body too just to be safe. After that, I replaced the spark plugs, which were old and horribly off gap. I put a new set of 7mm wires on just for good measure. The EGR was easy to pull & heavily gunked with carbon, not allowing the piston to move smoothly & hanging. Simply scraping the chamber with a screwdriver & a little carb cleaner can go along way. Once again, flash your codes & it'll give you a good place to start. Hopefully you can figure it out soon. Link to comment Share on other sites More sharing options...
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