O2 sensor passenger side pita

[Wigert]

Okay guys, it's my turn to replace the o2 sensors. Driver side went fine. I have read about the other one being problematic.. I have removed the 45 degree bracket like other threads pointed out. Would it help to remove the plate mounted to the block or do I have to manipulate it like it is? I am a bit afraid to loose the other connector so I can't reach it... 1292812929

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[Z51JEFF]

You?ve got everything off that needs to come off. How I did mine was I took a long,thin STANDARD screw driver to release the tab on the plug to release it. To plug in the plug on the new part I put a wad of DUM DUM on the end of the screwdriver to hold to plug as I get it lined up the the other end of the plug. Once lined up keep pushing until the tab locks in place. DUM DUM is a black sticky type stuff used as seam sealer between panels. It is a pain in the @$$ it basically you just have to do whatever works.

[Wigert]

A big thanks for the reply! I very much appreciate it. Is there something holding the connector in place upstream? Can one in other words push the new sensor connector against the other one without it going further up/in?

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[Z51JEFF]

A big thanks for the reply! I very much appreciate it. Is there something holding the connector in place upstream? Can one in other words push the new sensor connector against the other one without it going further up/in?

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I think it is held in place but I?m not sure,been awhile.

[Paul Workman]

I suggest that IF EVER headers are installed, goto Summit Racing and get a pair of O2 bungs (and a couple O2 plugs too to plug the old holes), and mount them on the outside (lateral) side of the collector. Then you can access the O2s w/o even jacking up the car!

NOTE: IIRC, I spliced in a new, extended reach pigtail and wrapped it in a heat wrap and tucked it under the heat shield. Has worked for going on 9 years and 30k miles with no problems (with the wiring - did just change the O2s as part of an unrelated experiment).

Ask Marc Haibec how he likes the setup!:thumbsup:

[ram_g]

Would it help to remove the plate mounted to the block

According to the 1991 FSM, on the passenger side, you have to remove the "sheet metal plate" held on to the oil pan with 2 bolts. Unfortunately there is no diagram, but since it specifically mentions oil pan and 2 bolts, I don't think it's referencing the diagonal brace.

Apologies I haven't looked myself, but this plate that you mention - is it attached to the oil pan specifically? Any idea what purpose it serves / what the other end is attached to? It could in fact be the plate referenced in the FSM that needs to be removed to access the connector.

[Wigert]

I suggest that IF EVER headers are installed, goto Summit Racing and get a pair of O2 bungs (and a couple O2 plugs too to plug the old holes), and mount them on the outside (lateral) side of the collector. Then you can access the O2s w/o even jacking up the car!

NOTE: IIRC, I spliced in a new, extended reach pigtail and wrapped it in a heat wrap and tucked it under the heat shield. Has worked for going on 9 years and 30k miles with no problems (with the wiring - did just change the O2s as part of an unrelated experiment).

Ask Marc Haibec how he likes the setup![emoji106]Thanks for the suggestion. Headers is not on my road map any time soon but I will keep this in mind.

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[Wigert]

According to the 1991 FSM, on the passenger side, you have to remove the "sheet metal plate" held on to the oil pan with 2 bolts. Unfortunately there is no diagram, but since it specifically mentions oil pan and 2 bolts, I don't think it's referencing the diagonal brace.

Apologies I haven't looked myself, but this plate that you mention - is it attached to the oil pan specifically? Any idea what purpose it serves / what the other end is attached to? It could in fact be the plate referenced in the FSM that needs to be removed to access the connector.Thanks for the input! The plate in my photos looks like it could be removed and pulled out. What section in your FSM did they mention it? I too have a FSM but for the 1990 but did not find much regarding the oxygen sensor removal process...



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[ram_g]

What section in your FSM did they mention it?

In my '91 FSM (electronic version) it's on pages 6E3-C1-16 and -17 under "Driveability and Emissions 5.7l (VIN J)".

It's pretty underwhelming, very scant directions!

I can see about posting a pic of the page later.

[Wigert]

In my '91 FSM (electronic version) it's on pages 6E3-C1-16 and -17 under "Driveability and Emissions 5.7l (VIN J)".

It's pretty underwhelming, very scant directions!

I can see about posting a pic of the page later.Thank you very much for the reference, I now managed to find that same section in my FSM. It is clear that I need to remove the plate as well. Hopefully that will simplify things.

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[ram_g]

Thank you very much for the reference, I now managed to find that same section in my FSM. It is clear that I need to remove the plate as well. Hopefully that will simplify things.

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Post an update when you get a chance!

[Wigert]

So there is a cable clip pushed into the plate and I don't think I can get it loose with out cutting it... Spent 30 min trying to get it out..*arg*.. I guess it is impossible to know if I can do without something holding the nearby cable right there but I might have to go that route.

The struggle continues...

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[Subfixer]

I could not dislodge the connector from the plate on my 92 either.
Finally used the long screwdriver method.

[Wigert]

Today I had some more time to work on this. I was able to remove the clip from the plate. It helped to temporarily remove some of the plastic around the cable near by. Eventually I got the o2 sensor connector loose. Soon it's time to remove the sensor after some lubrication. And then we will see if I can get things back together...12952

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[Wigert]

I have replaced the last sensor and Iam putting things together. What does the picture tell about the left and right side? The left one is new, the middle is left side and the right is from the right side. There is a noticeable difference in color... 12956

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[ram_g]

I'll wait to hear what other more experienced folks have to say about the color, but meanwhile I'll note that the removed left and right sensors are not the same part (look at the shape). Maybe someone previously replaced the left (driver) sensor but gave up on replacing the right (passenger) one due to the difficulty involved!

[Wigert]

That is a good observation! Maybe someone gave up on the right side as you pointed out.

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[Wigert]

If someone else will be doing this the torque specs might be useful to know (at least valid for 1990):

Two oilpan bolts 10 NM
Two front crossmember rear brace to front side member bolts 58 NM
Two front crossmember rear brace to drivetrain and front suspension frame bolts 56 NM
One engine mount frame nut 54 NM

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[mhobtr]

I cut the wires at the sensor and installed a new Weatherpak connector. Plugged in the new sensor and looped the wires up and out of the way and was done.

Later, when i installed my OBX headers, I didn't have to find a harness extension.

[ram_g]

I cut the wires at the sensor and installed a new Weatherpak connector. Plugged in the new sensor and looped the wires up and out of the way and was done.

Later, when i installed my OBX headers, I didn't have to find a harness extension.

Now that is a good idea!

Are the two white wires interchangeable? Otherwise how did you determine how to wire the connector properly?

[Perry Mitchell]

That's a good idea however I was told by the experts on this forum that the O2 wires need to be open to the atmosphere so they can sense the oxygen. I had to remove the heat protection wrapping from my wires to get them to work as they should. I don't know what the shortened wires with an added connector will affect.

[mhobtr]

Now that is a good idea!

Are the two white wires interchangeable? Otherwise how did you determine how to wire the connector properly?


I believe the two white wires are the element heater circuit and are interchangeable but I tried to put them in the connector in the same slot anyway. If you can't see the connector hidden by the plate, you can use the driver side connector as a guide. Before I cut them, I used some colored tape to ID them. Save the heat shielding tube and reinstall it before you put the pins in the connector.



Weatherpak connectors are great. If you happen to put a pin in the wrong slot, they can be easily removed with the correct tool and reinserted. (Or, if you forget to put the heat shield tube on as I did, you can fix your screwup).

[ram_g]

Perry - you aren't shortening anything with this - you actually end up with more wire to the sensor.

IMHO the elegant part of this is that if you really screw up, you haven't lost anything as you are not making any changes to the new sensor or to the permanent harness. Just unplug the original sensor wiring (noting the difficulty of access, etc.) and plug in the new sensor.

[mhobtr]

That's a good idea however I was told by the experts on this forum that the O2 wires need to be open to the atmosphere so they can sense the oxygen. I had to remove the heat protection wrapping from my wires to get them to work as they should. I don't know what the shortened wires with an added connector will affect.

You cannot seal the end of the OX sensor where the wires enter the unit, they must stay open to allow the sensor to breathe.



The wires in the Weatherpak connectors on the other hand are sealed to prevent moisture entering the terminals. Adding a splice harness, if done correctly, will not create sensor circuit problems. If this were an issue, you wouldn't be able to install headers.



You don't cut the wires on your new sensor, you cut them off the old one. If for some reason you had to cut the harness on the sensor to be used, you would have to be sure to leave space for the sensor the breathe.



I am confused as to why you had to remove the heat shield on a new OX sensor, it should have come with adequate gap for air. What brand sensor had this problem?

[Perry Mitchell]

[QUOTE=mhobtr;314225]I cut the wires at the sensor and installed a new Weatherpak connector. Plugged in the new sensor and looped the wires up and out of the way and was done.

Later, when i installed my OBX headers, I didn't have to find a harness extension.[/QUOTE
My fault. I thought you cut the wires close to the sensor and added the new connector too close for the sensor to breath. What you did is made your own extension. I kept the factory shield on the wires but added additional heat wrap which was secured at each end with heat shrink to keep it from unravelling since it was a woven material. Sorry for the confusion.