You could try using a DVOM not sure you could track the rise and fall of of the voltage quick enough. Alternatively you could use a low wattage 12V test light.


Written instructions here.

EEC IV Self Test ? Ford Fuel Injection and EEC IV Electronic Engine Control ? EEC 4 ? OBD/OBD2 Trouble Codes

 

FYI - The 1986 does not have a "MIL" light.

This "Check Engine Warning Indicator" was not operational in the EEC-IV F-150 until the 1988 model Year.

 

Tom,

“tester and the book”

Pick up an automotive light probe for your code reading, non-LED, they are less than $10, and very handy for automotive electrical troubleshooting down the road. Until then you can use your meter to make some other measurements.

The book is a good reference, but the lads here can eventually guide you through a logical troubleshooting process for this 86’ 5.0L EFI.

“making sure the O2 sensor was hooked up”

The key is, is the O2 signal voltage making it back to pin 29 on your ECA. This is something you can measure with your digital meter.

In 1987, there was an “Engine Warning Indicator Module” circuit added to the F-Series Instrument Cluster. This circuit has an “Engine Warning Indicator” light.
This light is not connected to the ECA, just your gauges.

This replaced the “Instrument Voltage Regulator” normally found in the 86’ models.

What is your build date?

 

So, can you define how your engine was running before you first disconnected the O2 ?


Also, define your current Cold Engine Start-Up scenario ?

First 30 seconds; ? How does it run, what are your RPMs ?

Next 2 minutes; ? How does it run, what are your RPMs ?

Etc.

 

Depending on your other answers (like was it running rich before the O2 event), one would think if everything was working ok before you disconnected your O2 wire, then the O2 would be my first task.

Originally in 86’, the O2 lead has a round connector attached. That connector is upstream from the O2 near the wire bundle that run up behind your engine on the passenger side, just above the Exhaust Manifold.

In your case, the O2 has been replaced, but they may have tapped into the original wire near the O2. So, if you can follow that wire up to the connector, you can open the connector and read the voltage generated by the O2 when it is hot.

This will test the O2, and the crimp connection for continuity.

If the connector option does not work out, you can remove the crimp connection and test the output of the O2 there. Then solder the old connection and you can be guided to check the voltage @ pin #29 at your ECA 60 pin connector. (Personally, I wold go to the crimp first)


Your meter ground connection to the engine/body is important for the reading, and for the O2 to work properly.

The O2 uses the Exhaust Ground to the Engine Ground for its connectivity. (bad idea, that was improved with time) Sometimes this is the reason for O2 failure.

Be sure your Engine Ground to Battery Ground connection is cleaned and tight.
Be sure your Engine Ground to Body Ground connection is cleaned and tight.
Be sure your Body Ground to Battery Ground connection is cleaned and tight.

 

You may have to acquire a few extension cables for your meter leads, I use alligator clip cables all the time.
Gets you further away from the exhaust pipe and out from under the truck.

Examples;

 

1 what voltage value should I read and where is pin 29 and 64, (I will find a drawing)
2 yes, it clearly says "Emissions" in the most left block on the upper dash or am I totally not getting what your asking?
3 my build date is 86 and that is based off of the VIN 10th digit "G"
4 first start up cold scenario=normal higher rev for about 15 seconds and is rough but not as bad as when it eventually kicks down after a short warm-up, which leads to the sputter/chug/almost die then rev back up then repeats till it dies out on it's own.
5 it was running smooth and powerful till I pulled that O2 plug, which took a few days/trips to reveal this issue.
6 I understand what you mean by follow the O2 wire to disconnect and test there, but not 100% on testing for voltage generated by the O2 sensor, a sensor can generate voltage on it's own?

Yes to getting some extension leads for easier testing!

 

IIRC, that Emissions lamp on the dash was tied into the "inferred mileage sensor" and would come on to remind you to replace some part (like EGR and O2 sensor). Then you reset or unplugged the sensor and the light would go off.

 

“1 what voltage value should I read and where is pin 29 and 64, (I will find a drawing)”
Approximately 0.0 to 1.0 volts, pin 29. (I’ll dig out the lean/rich values)

“2 yes, it clearly says "Emissions" in the most left block on the upper dash or am I totally not getting what your asking?”
Ok, news to me, but good. Do you have your owner’s manual?

“3 my build date is 86 and that is based off of the VIN 10th digit "G"”
Glad you verified the year. The build date is on a sticker inside the driver door frame, month and year I think.

“4 first start up cold scenario=normal higher rev for about 15 seconds and is rough but not as bad as when it eventually kicks down after a short warm-up, which leads to the sputter/chug/almost die then rev back up then repeats till it dies out on it's own.”
Ok, thanks

“5 it was running smooth and powerful till I pulled that O2 plug, which took a few days/trips to reveal this issue.”
OK, could still be a coincidence situation, don’t count it out.

“6 I understand what you mean by follow the O2 wire to disconnect and test there, but not 100% on testing for voltage generated by the O2 sensor, a sensor can generate voltage on it's own? “
Yes, the O2 generates 0.1 to 1.0 v depending on temperature, fuel and air mix, you can read plenty on this. (Knock Sensor generates as well)

 

Silly me,
Here I thought an O2 sensor located in the exhaust would be related to an emission warning light.

Learnin

 

CountryBumpkin is right, nice catch....

But, I didn't think the "Emissions" light was added until 87'. I'm guessing you are late year model, always some crossover year to year. 86' was the first F-Series EFI, an I have seen & read of many changes by 87 MY. 87' MY final design is in 86'.

 

This should help;

 

A page from my 86' shop M. (Has a light), should have looked in there earlier.

 

I'm on it, it'll take a bit to give you some results, and thanks!

 

No worries, no rush, everyone has other things to do............