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Discussion Starter · #21 ·
Pin 29 i believe, here is a link to 86 stuff, study it, its very helpful.





This is from the EEC section showing o2 sensor pin numbers 29, the eec has numbers on it for reference.


View attachment 178957 .
Awesome, thank you...will def study it! Just FYI, I did install the new air intake temp sensor and there was no change.
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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That was why I said to measure resistance on the sensor, to make sure its a bad part before replacing it. Of course i did the same thing too, just replaced the part because it was old, and the new part failed 4 months later. I then learned to measure resistance on the sensor itself, which I then learned my original one was in spec... new parts aren't very good, so always try to get Motorcraft parts.

Let's see what your fuel pressure is when you get a gage??
 

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Discussion Starter · #23 ·
That was why I said to measure resistance on the sensor, to make sure its a bad part before replacing it. Of course i did the same thing too, just replaced the part because it was old, and the new part failed 4 months later. I then learned to measure resistance on the sensor itself, which I then learned my original one was in spec... new parts aren't very good, so always try to get Motorcraft parts.

Let's see what your fuel pressure is when you get a gage??
Oh, I did, I posted the results a few posts ago. It tested 2.45v via the connector and only 19k ohms on the posts of the sensor itself.

Just finished replacing the HP fuel pump and another new filter (had spare on hand, had previously replaced it a few months ago during oil change).

Fuel pressure test kit will be here in the morning and I'll post those results then.

Oh, and O2 sensor is getting a signal to the ECC too.
 

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Discussion Starter · #25 · (Edited)
Ahh, good to.see you're figuring things out quicker than I did, let's hope its a simple fix. See what that fuel pressure reads & go from there.
Yeah, even though it didn't fix it, I'm glad a failing part got identified and replaced. Really appreciate your help bud!

Will do fuel pressure tests tomorrow morning but will be replacing the LP fuel pump, filters and sending unit in the tank anyways.

Just to recap what's been done so far:

Replaced:

Cat, plugs, wires, rotor, distributor cap, IAC, all vacuum lines (5/32 rubber hose), intake air temp sensor, HP fuel pump and fuel filter.

Tested good:

MAP, timing, EGR and O2 sensor to ECC.

And, so far, nothing has made a difference. It idles very rough, surges, pops/backfires through the intake, smells of fuel and takes feathering of the throttle for about a minute before it'll idle on it's own (still surges though). After it warms up it'll die when stopping (intermittently) as well as coasting (also intermittent) and sometimes will fire right back up while other times it has to crank for 5 to 10 seconds to start again.

The only meaningful code it's throwing is 13... which, isn't very meaningful, lol!
 

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1986 Eddie Bauer 5.0EFI AOD Full length headers Y pipe into single 3" Magnaflow 3" factory exit
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Not that this is a fix, but to make sure all of your wiring looks good, I know mine was pretty brittle & corroded internally and I had to replace sections of it, and clean connectors as well. I found this by testing at the pin, when sensors tested good, and voltage at the sensor was good, that voltage at the pin was not the same because of corrosion. Make sure all of your grounds are clean, and your main ground from the battery, to the frame, then the engine block is good, mine was so corroded it fell apart in my hands when I checked it. None of this guarantees a fix, all of these things add up.
 

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Yo PHRoG,

wm86-bronco-wiring-diagram-section-2.jpg
Screenshot_20200518-110413.jpg
Yo ,
178961

O2 Wiring Diagram in an 86 by Xris

178960



EEC IV 60 PIN CONNECTOR LEGEND @ Ford Fuel Injection by absent member Fireguy50 (Ryan M)

EEC IV 60 Pin Connector Pin Diagram by absent member Fireguy50 (Ryan M)
 

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Discussion Starter · #28 ·
@miesk5 thanks for the detailed tech info. Just FYI, this is an 86, 5.0 EFI and doesn't have the heated O2 sensors...just the single-wire unheated one. I tested the TAD/TAB vac solenoids and they were 70ohms, so within spec I believe. The EGR vac ones tested at only 40ohms though...I couldn't find a reference for those...do you know if that's within spec?

@Rob_64-365 the fuel pressure testing kit I ordered got delayed so I just went forward with the low pressure in-tank fuel pump replacement and discovered (as is common) it was starting to leak due to corrosion. So I've just ordered a new tank, hose to the filler neck, breather valve and seal and it all should be here Friday.

On a positive note, I finally got the O2 sensor out...had to remove the tranny dispstick and use an impact but it finally came out and oh man, was it trashed!

20210503_170626.jpg


Thanks again for all the help. Will update results this weekend when the parts come in and I get it all out back together!
 

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Yo PHRoG,
Sorry for that mix-up.
179082
179083
 
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