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Sounds like you are on the right track with an open circuit between the sensor connector and the PCM. I would start by tracing the harness from the 02 sensor to the PCM looking for damage, etc. Also check the harness side connector for corrosion, damage, etc. Also possible you have some weird internal issue in the PCM.
 

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Discussion Starter #42
Sounds like you are on the right track with an open circuit between the sensor connector and the PCM. I would start by tracing the harness from the 02 sensor to the PCM looking for damage, etc. Also check the harness side connector for corrosion, damage, etc. Also possible you have some weird internal issue in the PCM.
Thanks that pretty much just what I was thinking. On ebay I did pay I think 10 bucks for the ford technical manual, and just now having a good look at it. there is a specific set of pinpoint test I can perform to figure this out without cutting any wires till I am sure. I will attach the portion so others who use the site may help someone someday. Also note I stole the images of the pcm pins from somewhere in this forum.
 

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Discussion Starter #43
Noticed watching live data and having my gf jiggle the engine harness o2 sensor would start to show functioning but the car would start to stall. Stripped all the protection from the pcm down to mid motor on the motor harness. And behold, lots of chafing and obviously areas that have been worked on before. what do you think is the best wrap for some of the chafed wires? Just looking at them, some I will probably have to be replaced/soldered in.
 

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I like heat shrink tubing on wires that are going to be soldered back together. Electrical tape is next best thing but you can also use self fusing silicon tape but that gets pretty bulky. Never used it but might work well is liquid electrical tape.
 

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Discussion Starter #45
I like heat shrink tubing on wires that are going to be soldered back together. Electrical tape is next best thing but you can also use self fusing silicon tape but that gets pretty bulky. Never used it but might work well is liquid electrical tape.
ended up replacing the o2 sensor signal wire to the pcm completely and resolved the issue. Now I just have to figure out why I am getting P1633: Keep Alive Power Voltage Too Low, that causing the cars idle to surge or stall. guess I am going to have to trace this one out to lol.
 

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Discussion Starter #47
I have the ac unplugged and ac relay out at the moment. fixed the issue, the pcm harness wasnt tight enough. But o2 sensor issue is back lol
 

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Discussion Starter #48 (Edited)

I am beginning to wonder if it is the pcm itself. From the video you can clearly see the voltage from the o2 sensor at the pcm but on my live data nothing. Not sure if it is making a good connection and for obvious reasons I dont wanna buy a pcm just to see if thats the issue. Further suggestions? Note the butt connections are temporary, I have a brand new wire on its way.
 

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Discussion Starter #49
Figured it out

somehow the plug connector isnt making a good connection with the o2 sensor. I straight pinned the power/ground to the o2 sensor and started the car, o2 is working correctly that way. So this might be sorted tomorrow. Thanks for the tips.
 

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Discussion Starter #50
SO now, I have no codes to target. No vacuum leaks I can see or hear. Th car has brand new spark plugs, coil pack, fuel filter, and new MAF. Cleaned IAC abit ago, but did note small amount of oil in it. Also, trottle body is sparkling clean. Idles like total crap until the car reaches full temperature, then runs without much issue, engine still a little jumpy at that point. I have not took it to a mechanic primarily because I am doing the work on self on free time and I have a working vehicle. Any great ideas, cause I am getting to a point where I am at a loss?
 
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