I have a 1995 F-150 5.0 4X4 with auto trans 232,000 miles. Truck started running poor so I ran codes and got a 172 so I changed the o2 s and a few days later same problem , I checked for vacuum leaks and cleaned all the grounds under hood cleaned plug . Now when I run the codes I get koeo 111 then 10 for separator then no continuous code like the computer is whacked . I unplugged the o2s and drove truck and the check engine light comes on then goes off should it not stay on constant with the o2s unplugged . My last training on this stuff after being a mechanic for 50 years was in 2014 when I retired Just wondering if I'm overlooking something cause I'm old.

 

Define "running poor"

 

"Running poor" isn't much of a description for us to go on - what exactly do you mean? It seems like you're overlooking diagnosis. Codes don't simply mean to change parts. Did you test the previous HEGO? Did you test the replacement? What brand/PN/source is it? There aren't many sensors, and most are very easy to test - test them.

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Did/does the truck have any symptoms of running lean? What do the spark plugs look like? Compare them to the inside back cover of Haynes. Follow the links in this caption:

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What's the fuel pressure? How many miles on the fuel filter? What's the compression? Is manifold vacuum at idle normal? How much oil pressure does it make at idle? Does it increase at higher RPMs? Does it stay there as the engine warms up? How much slack is there in the timing chain?

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No, it's not likely that the EEC is bad. '94-up EECs don't have this type of capacitor or problem:

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But they CAN suffer from this:

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Have you looked inside the EEC? You should put ALL the truck's details into your signature.

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Running poor as in extreme loss of power intermittent in conjunction with check engine light . Tested the o2s before buying one . Fuel pressure good, I've done all the checks as you guys say . I 'm trying to figure why when I scan I can't get a continuous code read as I said I get 111 10 and code reader quits scanning like its getting nothing from ecu Should I not have have a constant cel with the o2s unplugged and that's not happening . I am getting various voltage reading on power supply to the o2s which should be 12v . Truck runs like a raped ape with o2s unplugged . Just want to not overlook something before I remove ecu to look inside it .

 

A bad HEGO will not cause intermittent extreme loss of power. Unplugging things is not diagnosis or repair, and unplugging the HEGO will not cause the CEL to be on continuously. Looking in the EEC takes a little effort, but it's not destructive or even risky. Your description of the symptoms & what you're doing is too vague for me to help.

 

Problem solved a bad o2s new in box . The loss of power is when the ecm goes from closed loop to open loop back and forth . I cleaned all connections from ecm to sensor including the grounds . Bought another o2s then had to argue with parts person about the one bad out of the box . I worked over 50 years for Ford used to be a mechanic then they called us Techs . My last years before retirement in 2014 was mostly diesel . Quality control on parts has changed over the years had allot of problems with bosch replacement parts .