Screw you O2 sensors!!!!!

[Ramcharger90]

So finally broke down and wired up the O2 harness I got and the power wire for the harness wired in. And guess what.... it runs like total garbage now. So they now get unplugged and left that way oh well if it runs rich. It was popping and back firing. Also had alot of hesitation. I dont know what should be done.

 

[Dirtman]

Not sure the whole backstory here but the o2 sensors set the fuel trims and take time to adapt... did you reset the ecu before plugging them in and starting it up? And how long did you run it with them plugged in?

 

[Ramcharger90]

Not sure the whole backstory here but the o2 sensors set the fuel trims and take time to adapt... did you reset the ecu before plugging them in and starting it up? And how long did you run it with them plugged in?

I drove a couple of miles with them plugged in and I shut it off and unplugged the harness and then started it and it ran beautifully instantly after restarting it.

 

[Bird76Mojo]

When running Foxbody V8 swap stuff, there can be some confusion with the O2 sensors and harnesses. There were two different O2 harnesses used in the Foxbody. I think the automatics used a different harness and sensor than the manual trans cars.

https://forums.corral.net/forums/ge...manual-auto-differences-year-differences.html
https://forums.corral.net/forums/electrical-wiring/1449089-o2-sensor-harness-differences.html
https://forums.corral.net/forums/ge...gen-sensor-harness-manual-auto-how-repin.html
https://forums.corral.net/forums/ge...0-a9p-a9l-oxygen-sensor-harness-question.html

https://www.stangnet.com/mustang-forums/threads/1987-o2-harness-question.884039/

 

[rusty ol ranger]

So finally broke down and wired up the O2 harness I got and the power wire for the harness wired in. And guess what.... it runs like total garbage now. So they now get unplugged and left that way oh well if it runs rich. It was popping and back firing. Also had alot of hesitation. I dont know what should be done.

Shoulda just used a carburator. Twist some screws...done. lol.

If its running rich with the O2s that means its actually lean...vaccuum leak maybe?

 

[Ramcharger90]

Shoulda just used a carburator. Twist some screws...done. lol.

If its running rich with the O2s that means its actually lean...vaccuum leak maybe?

No, as much as I like carburetors I would prefer fuel injection on this not only since OBD1 but it was more of a challenge. Also it's running rich w/o the o2's plugged in. With them plugged in, it back fired was popping and hesitating.

 

[Ramcharger90]

When running Foxbody V8 swap stuff, there can be some confusion with the O2 sensors and harnesses. There were two different O2 harnesses used in the Foxbody. I think the automatics used a different harness and sensor than the manual trans cars.

https://forums.corral.net/forums/ge...manual-auto-differences-year-differences.html
https://forums.corral.net/forums/electrical-wiring/1449089-o2-sensor-harness-differences.html
https://forums.corral.net/forums/ge...gen-sensor-harness-manual-auto-how-repin.html
https://forums.corral.net/forums/ge...0-a9p-a9l-oxygen-sensor-harness-question.html

https://www.stangnet.com/mustang-forums/threads/1987-o2-harness-question.884039/

You are correct if you try too use a automatic transmission o2 harness with a manual transmission computer you will burn up the computer because it is pinned differently and will send power to the wrong place in the computer. Also the o2 harness is pinned Differently from a 87-90 and 91-93. I bought a brand new Ronaldo Francisco O2 harness from LMR or AM and it came with instructions for my 91-93 harness. I Also needed a 12v constant with key on wire to get tied into the grey and yellow wire on the green plug near the mustang ECM.