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1986 Bronco 302, 1965 Ford Fairlane 289
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Discussion Starter · #1 ·
1986 Bronco 302.
I've got stalling and idle fluctuations, hot or cold. More so noticeable past high idle on start up obviously.

After months of hacking down these codes, I'm left with this code 18. Reading up on it here, there isn't a clear solution and seems to be a nightmare.

I've been going off of Miesk's advice, but can't seem to find the issue.
Everything seems to be checking out. TFI is new and tested good. Remote mounted to the front inner fender behind drivers side headlight. Ground is good. SPOUT functions when connected/disconnected.

Except this:
Spark Timing Advance Test #8
Spark timing advance is controlled by the EEC system. This procedure checks the capability of the ignition module to receive the spark timing command from the EEC module. The use of a volt/ohmmeter is required.
1 - Turn the ignition switch OFF.
2 - Disconnect the pin-in-line connector (SPOUT connector) near the TFI module.
3 - Start the engine and measure the voltage, at idle, from the SPOUT connector to the distributor base. The reading should equal battery voltage.
4 - If the result is okay, the problem lies within the EEC-IV system.
5 - If the result was not satisfactory, separate the wiring harness connector from the ignition module. Check for damage, corrosion or dirt. Service as necessary.
6 - Measure the resistance between terminal No. 1 and the pin-in-line connector. This test is done at the ignition module connector only. The reading should be less than 1 ohms.
7 - If the reading is okay, replace the TFI module.
8 - If the result was not satisfactory, service the wiring between the pin inline connector and the TFI connector.


SPOUT connector has only 6.77 volts. Alternator is charging and battery is good.
TFI connector is good.

So my question is what needs to be repaired to bring that voltage back to battery voltage?
If it was grounded wouldn't it short out? Could it be a bad ground causing only half the volts?
I assume it grounds in the EEC Pinouts 20,40 or 60. I'll check these tomorrow.
Can I check resistance from SPOUT connector at the TFI, back to the EEC connector to rule out bad wiring?
Or could this be a bad IDM circuit, or bad computer?

This is the last engine related thing holding me back from being a daily driver, any advice will be very much appreciated!

-Matt
 

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1986 Bronco 302, 1965 Ford Fairlane 289
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Discussion Starter · #3 ·
Well after my father in-law became positive with COVID19 and is now hospitalized, a state patrolman who is 55 and having to work these riots, being around him my wife, child and myself had to quarantine. This gave me a lot of time off work to do these tests....

I found the 22k ohm resistor had some really gnarly wiring. Replaced it and so far my codes have gone away.

Rode really good for a few miles and went to surging, shut it off to pull codes, no KOEO codes, went to crank for KOER codes.... Crank, no start.

Ground wires are really hot after cranking a few seconds. I wonder if the code 18 could be triggered from an internment ground issue. Ran it at idle twice and no surging, I wonder if hit a pothole could have flexed the cable.

Yo Matt,
Check wiring, and those grounds.
See Seriously... Has Anyone ever dealt with a DTC Code 18...
By Seattle FSB

Here is EECIV CONNECTOR LEGEND BY RYAN M @ Ford Fuel Injection

Will bbl. I have an appointment.
 

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Yo Matt,
Best to your father in law!
Inspect and clean negative battery czble grounds or go to high gauge negative battery cables, such as
Wire Upgrade, using O Gauge Welding Cable in an 86
Check the battery ground cable train from battery to block, to frame.
Look for wire strand corrosion under insulation at negative post connector and at conbections to block & to frame.

"Using "O" gauge welding cable I ran it back, tie wrapped inside the frame, to a common grounding junction which also connects to the negative post of the battery. No more grounding interuptions !"
162952

Source: by Sixlitre (Malcolm H, Eddie Bauer)

Some grounds Locations in an 86 (see #5); G701 Behind IP near RH side of radio; G801 On LH inner fender behind headlights; G802 On RH inner fender behind headlights;

G903 At LH side of rear crossmember;
G909 at lower LH cowl access hole;
G1003 On LH side of frame behind front crossmember;
G1006 Rear LH side of frame at rear crossmember;
G1303 at LH radiator support

Source: by Seabronc

Here is the 1986 Bronco ELECTRICAL & VACUUM TROUBLESHOOTING MANUAL (partial) by Gary @ 1986 EVTM - Gary's Garagemahal (the Bullnose bible)
See more info by Gary, such as 1985-1986 Fuel System Adjustments @ 1985-1986 Fuel System Adjustments - Gary's Garagemahal (the Bullnose

See Start & Ignition
 

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1986 Bronco, 5.0 nothing special... yet!
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22 Posts
Matt,

we’re you ever able to resolve this issue? I am fighting a similar problem.

thanks
 

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Yo Guy

Matt last logged in here 3 months ago
 
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