84 AE zirconium O2 sensor melted...

[bonfire79]

So, the sensor light illuminated on the dash recently. i questioned this since the car just past 50,000 miles.... 10k short of it coming on at 60,000 (30K interval). i figured maybe the system is just not accurate and activated early. After doing an under the hood inspection, I found that the O2 sensor harness plug (the plastic connection) is nearly melted and exposing everything inside. Looks like someone tried to ziptie it together and arranged it so that is near the exhaust, hence the heat getting to it. the only way I can think to repair this is to get another sensor with plug, and another harness with plug and located the plug behind a bracket to shield it from the turbo exhaust heat. So a few questions:

1) is this a reason that has caused the sensor light to turn on earlier than designed? i thought it only came on as a reminder to check the emission system every 30,000 miles up to 90K.

2) is the little bracket-clip that is attached to some of the frame work supposed to hold the harness in place in order to keep out of the heat? it looks like it. the plug is just kind of floating there on the wires.
i have circled this item in red on the attached pictures.

3) it is probably going to melt away until it breaks apart. if I keep driving in this condition, is it going to have any major or minor effect on the engine other than giving false O2 readings to the ECU?

lastly, does anyone have a spare O2 sensor plug and harness (both ends) for the 84-85 turbo car that they'd like to sell? looks like I'm going to need one. Please advise. Thanks.

Bon

[Z_Karma]

1) is this a reason that has caused the sensor light to turn on earlier than designed? i thought it only came on as a reminder to check the emission system every 30,000 miles up to 90K.

Which "sensor light" is on?. I've been through multiple O2 sensors on my 84T and don't recall ever seeing a sensor light.

2) is the little bracket-clip that is attached to some of the frame work supposed to hold the harness in place in order to keep out of the heat? it looks like it. the plug is just kind of floating there on the wires.
i have circled this item in red on the attached pictures.

yes, the male/female connector assembly is supposed to clip into that bracket to keep it off the manifold.

3) it is probably going to melt away until it breaks apart. if I keep driving in this condition, is it going to have any major or minor effect on the engine other than giving false O2 readings to the ECU?

You may experience a variety of abnormal idle/starting conditions due to intermittent connections or possible shorting, yes. If this is the original O2, it's probably due for replacement.


lastly, does anyone have a spare O2 sensor plug and harness (both ends) for the 84-85 turbo car that they'd like to sell? looks like I'm going to need one. Please advise. Thanks.

Those white Sumitomo connectors on the earlier models break with age. Nissan switched to a different material that is grey in later models. If you have a pick-n-pull nearby, you can harvest that 3 pin connector from anything late 80's to late 90's Nissan/Infinity. A new NTK O2 sensor will have a new male connector, you only need the female harness-side connector. Your cooked harness-side connector should be easily broken apart with a pair of pliers and doing this carefully should keep the factory crimped terminals intact. De-pinning the grey donor connector is not difficult and can be done with a dental style pick or small jewelers flat blade screw driver. Then insert the pins from your harness in the same order on the new connector housing. Same method as modifying the factory harness for a PRW2 connector.

I would do this rather than cutting and splicing in new wires, unless the contacts in the housing are damaged.

If you want, i have some grey female connector housings, i could de-pin one and ship it to you. lemme know.

But, learning to de-pin and re-pin these white connectors is a good skill to learn, because you have a lot of them in your AE.

[bonfire79]

Which "sensor light" is on?. I've been through multiple O2 sensors on my 84T and don't recall ever seeing a sensor light.

the main sensor light on the dash up in the left hand corner (on digital dashes); the orange/yellow one that says 'sensor' when it lights up. this is the one that in order to turn the light off, you have to manually reset it by pressing the switch located up in the dash behind the glove box. it should only come on at 30,000, 60, and so on...

yes, the male/female connector assembly is supposed to clip into that bracket to keep it off the manifold.

thought so. strange, my 87 did not have this piece... maybe it was removed previously, so i was curious

You may experience a variety of abnormal idle/starting conditions due to intermittent connections or possible shorting, yes. If this is the original O2, it's probably due for replacement.

it already has some slight hesitations at start up and idle and sometimes hesitates when on the throttle, but this is seldom. i should get another one, even though the car is only at 50,000 original miles

Those white Sumitomo connectors on the earlier models break with age. Nissan switched to a different material that is grey in later models. If you have a pick-n-pull nearby, you can harvest that 3 pin connector from anything late 80's to late 90's Nissan/Infinity. A new NTK O2 sensor will have a new male connector, you only need the female harness-side connector. Your cooked harness-side connector should be easily broken apart with a pair of pliers and doing this carefully should keep the factory crimped terminals intact. De-pinning the grey donor connector is not difficult and can be done with a dental style pick or small jewelers flat blade screw driver. Then insert the pins from your harness in the same order on the new connector housing. Same method as modifying the factory harness for a PRW2 connector.

unfortunately, i don't have access to any pick-n-pulls as they don't have many junk yards here in the UAE like they do in the U.S., so i am pretty relying on the mail system. I saw an NTK sensor online but it was the smaller titania, however I found some others that have the grey style connector, also nissanpartsdeal still has the OEM sensor available too. I can try this fix on the pins for the female connector. doesn't seem too difficult a task, other than that it is very hard to work in that area where the sensor is located, let alone get my hands down in there.

I would do this rather than cutting and splicing in new wires, unless the contacts in the housing are damaged.

agreed. i took another look at the connector and it doesn't look as bad as i thought, however i can see the internals through the cooked portions of the plug.

If you want, i have some grey female connector housings, i could de-pin one and ship it to you. lemme know.

I'm open to that sir, so if you can send 'em, i'll take 'em. how much do you want for it? and can you ship to military APO?

But, learning to de-pin and re-pin these white connectors is a good skill to learn, because you have a lot of them in your AE.

yeah for sure. all those connectors always seem to just go to crap. fortunately my Z31 is in pretty darn good shape and most things under the hood are pretty clean, but not all. any ideas on how to replace or repair all the little wire boots that tend to detach away from most of the connectors? think TPS, and AAR valve connections for example.... those are always falling apart on these cars.

So what I have decided to do temporarily, is put some electrical tape around the O2 connector and try to seal off and cover the melted areas and then remount it to the plug bracket. that way its away from the exhaust and is still intact. i just hope it doesn't have some kind of short which may have caused it to melt, but I still think it was the exhaust heat anyways. once I get the new sensor and plug terminals, i can repair those and then manually turn that reset switch under the dash and turn that sensor light off. hopefully all will run better afterwards.

listen, thanks a bunch for the information. really helps. appreciate it.

Cheers,

Bon

[8631z]

there is a wire under the drivers side dash that you can disconnect. has a little tag on it. that shuts the sensor light off. otherwise behind the glovebox is a hold relay that will keep it off for ~30000mi.

also the o2 sensor connectors are very susceptible to melting on the exhaust. there might have been a little clip that held it away from the exhaust but never the less the little bugger finds its way to get melted.

[bonfire79]

yes. i've read about disconnecting that little wire. pretty easy to get to. my car is less than 10,000 miles away from 60,000, so i am expecting the light to kick on again. maybe i will just disconnect the thing.

there is a metal clip that is attached the master cylinder heat shields that is supposed to keep the sensor away from the manifold. i was able to put the sensor connector back on the bracket and it is clear now of the exhaust. still, i wonder how it came off? sometimes i wonder what some of the old school engineers had for breakfast the day before they designed some of the systems lol

Bon