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86 Bronco II runs rough, loses coil signal


Bohemian Engineer

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Vehicle Year
1986
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Ford Bronco II
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I'm working on a 1986 Bronco 2 2.9 that was brought back from CA. Finally got it running, but not well. It usually starts right up, but misses intermittently.
I've been chasing my tail on it for a while, so any help is appreciated. Here's what I've tested and/or replaced:

New distributor (incl. TFI module, cap and rotor).
New coil
New plugs and wires

Tested fuel pressure, 32psi while running.
Tested for spark at the coil. Obviously has spark while running, but cuts out when the engine misses (so I know there's a spark issue, not fuel).
Power to coil is good.
Coil signal (green/yellow wire) cuts out when it misses.

Fault codes 67, 18, 22.

I feel like I'm forgetting to mention something, but that's all that comes to mind right now. I'll update if I remember anything else.
Thanks in advance for any help you can give!
 


Shran

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I'd be looking at your grounds in the engine bay first... one loose or corroded will cause all sorts of weird stuff. I fought a blinking headlight in my F150 for several years that ended up being a ground wire that I had detached and then just started the screw back in and never tightened it... jiggled around all the time as you can imagine.

If you can rule out all that, check your wiring to the distributor and coil for worn and shorted out spots

Next I would suspect the ignition module itself or the distributor...new does not always equal functional these days
 

RonD

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Always good to post code definitions since you probably looked them up and NO ONE has then memorized, lol
18 (R) Check base timing & advance function - Timing Tests
22 MAP (vacuum) or BARO signal out of range - MAP
67 Park/Neutral circuit fault - PNP

MAP sensor a big deal sensor on your engine, it can be on firewall or inner fender, not big, it has 3 wires and a vacuum line
Check its connector for corrosion inside
Check that its vacuum hose is "air tight" can hold a vacuum, no cracks

You TFI system has a SPOUT connector, SPark OUT, this is the "Vacuum Advance" for the spark timing on electronic ignitions
With engine warmed up you must unplug the SPOUT connector to set Base Spark timing with a timing light, 10-12deg BTDC
Then plug it back in and spark should advance to about 20deg BTDC if that part is working, the "advance" comes from the fuel injection computer
Which uses the RPMs, MAP sensor, and throttle position to determine engine LOAD

SPOUT connector looks like this: https://www.fordforumsonline.com/attachments/spout-jpg.866/
The smaller part pulls out all the way to disconnect "advance" so base timing can be set


Assuming automatic trans, the Neutral switch is on drivers side of transmission above shift rod, its round plunger type switch with 4 or 5 wires on the connector, this switch also activates Backup lights(reverse lights), so see if they are working
This code wouldn't cause your running issues
 

groovtubin

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After repairing a OPEN secondary coil wire to pin 5 at TFI connector, mine would IDLE perfect but TACH n engine miss every 15 seconds n HORRIBLE under throttle, took out the Advance auto TFI module the THREE tabs were THIN as ICE Orderd one from CarParts,com Nice THICK tabs n it runs PERFECT NO miss I took the Black advance auto module heat sinked the tabs added solder, n used fret file sandpaper for guitars to sand them down, for a spare..HTHs, course by now she should be a runnin! :) That green/yellow stripe wire follows the wire bundle in the Y, one side goes to coil, meets in middle ( spliced) one goes to TFI conn, and other goes to computer..it was probably getting redi to break, or your connector or tabs loose on module ?
 

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