1986 mustang shutting off, please help car is not driveable!!

[crazyfox]

ok, so I have a 1986 mustang gt 5.0 5 speed with speed density. issue i have is car starts to idle rough then shuts off. i have replaced the ignition module with a oem motorcraft unit as well as tried 3 other ones that i have. all did not change symptom. i installed a new coil and a new mallory billet distributor. i replaced the ignition cylinder as well as ignition switch. i also replaced the connector at the module and properly soldered the connections and used heat shrink. i also replaced the connector on the coil and used solder/heat shrink. i have checked the ground for the computer up near the battery and it is fine. i have wiggled all the wires in the harnesses in the engine compartment and none cause any issues. i have confirmed that it is not a fuel pressure issue as i have a inline spark checker hooked up to one of the ignition wires and observed at times you can hear the engine miss (and see no spark in the spark checker when it's missing). I checked for codes and the only ones are 31 and 82 due to me not having those systems hooked up (i deleted them). also just before the engine is killed the spark shows intermittant flashing and then no flash right before shutting down. I have great fuel pressure as checked by my underhood guage and hear the fuel pump prime and run when it should. one thing i can tell is when the engine dies it will not restart if turning the ignition key to the start position from the run position, but if i turn the ignition key back to off then to crank it starts up right away (and then the same sequence starts again). I am at a loss here,. I tried grounding the computer body to a good ground using a jumper wire from the case to a ground point but this made no difference. I took a video of what is happening for more clarification. right now I'm thinking either a problem with the computer itself or maybe the eec relay?
you can use the link to view the video i took of the condition. thanks (sorry for sideways video)
PAY PARTICULAR ATTENTION AROUND THE 6 MINUTE MARK ON THE VIDEO TO SEE SOMETHING REALLY BIZARRE

https://youtu.be/6tL5EP-OF1I

[Walking-Tall]

Besides... codes?... sounds like an ignition switch/circuit issue to me...

I have personally seen some under-dash wiring, connectors, and wiring to connectors being in just as bad or worse condition than the under-hood stuff on these...

[crazyfox]

Only codes were 31 and 82 due to me having those 2 systems deleted. ignition switch is new a few months ago (oem ford part)

[Walking-Tall]

New switch doesn't automatically mean good switch, and I mentioned under-dash wiring/plugs too.

Electric fan? While code 82, with KOEO, signifies "Secondary Air Injection Bypass MTA #1 solenoid circuit failure", it also refers to "EDF (Electro-Drive Fan) signal wire shorted to ground". (shorts to ground are never good)

"Electro-Drive Fan (EDF) control turns the low speed (primary) fan on and off. The EDF fan relay is part of the Integrated Relay Control Module (IRCM). The EEC-IV control module turns on the fan by applying voltage to the EDF pin to energize (close) the EDF relay.
Troubleshoot the circuit by checking the signal wire continuity from the EEC-IV control module to the IRCM, and by checking power, ground, and continuity in the fan circuit.
EDF Signal Wire Color - Tan/Orange"

I'll take and post the EDF electrical test procedures if your car has one...

(Quotes from Probst book)

[crazyfox]

no electric fan here, has a stock clutch fan only, a/c has been deleted as well.

[Walking-Tall]

Okay, well, based on the intermittent no start from Run to Start but start from Off to Start, I'm pretty sure the mounting screw holes on the ignition switches are somewhat slotted as to their mounting and functioning position in relation to the key cylinder's rod, and are to be set and tightened down with the key in a certain position, so I'd look into that, and I'd look at the condition and connection of the wires and their little connectors inside the big ignition switch connector.

[crazyfox]

ok, do you think I should check that before pulling the computer out and checking the eec relay?

[crazyfox]

would i have been able to install the switch and have no issue lining up the switch to coolumn screws? I don't recall any weird issues installing that switch when I did it a few months ago. I will check it and see though. Stay tuned

[Haystack]

Just pull the switch off the colum and start the car with a screw driver. If it stays running you've found the problem. This way you can also wiggle the switch around and try to find a bad connection.

[crazyfox]

little update, i checked for continuity between pin 60 at the computer (after unplugging the computer) and at the other end ground point near the battery. i have continuity between those points. i also noticed another black with green wire pin next to pin 60 and also have continuity between that pin and the ground point near the battery (yes I removed the eyelet from the fender when I checked this). I wiggled the wire harnesses around while the meter was hooked up and the beep signal never stopped. i opened the computer and thought I smelled a faint burning smell. only found 1 thing that is suspect and maybe it is how it's supposed to be? in photo my screwdriver is pointing at a spot where there is no wire between 2 solder points (not sure if that is an issue or not), the other thing is a blob of what looks like the rubber coating that is used on the circuit board (don't think it's an issue but I took a pic anyway). I will hook everything back up tomorrow and check that ignition switch again.

[Walking-Tall]

Yes, pin 40 wire connects with pin 60 wire, looks like by the wiring diagram, right outside of the ECU, connecting to the EEC power relay, and to the battery negative. No clue on the circuit board, other than those solder points don't look like anything was there that's just come clean off.

[crazyfox]

since I have the eec relay out of the car I decided to check voltage on the connector that goes into the relay. in picture one screwdriver points to terminal that showed constant 12 volts. all other terminals showed zero. this is with the key off and eec main harness unplugged. picture 2 screwdriver points to terminal that shows 12 volts with key in run position (salso shows 12 volts in crank position (note, i removed the starter wire from the fender mounted solenoid for this test (the wire that runs directly to the starter). any of this seem suspect?

[crazyfox]

if it stays running I found my problem (wouldn't it be the other way around? why would it stay running?

[Haystack]

Pins 20 40 and 60 are all grounds as well as a few other signs rtn pins.

[mustangs4me]

Correct me if Im wrong but you put a TFI on the distributor but not a hall effect inside?

[mustangs4me]

Is that a stock distributor or an MSD, sorry couldnt tell.

[crazyfox]

its a mallory brand new.

[mustangs4me]

How bout if you put a stock one back in?

[crazyfox]

ok, so I think I found the issue. I had the car running in the garage and checked the eec relay I found it to be very hot. i tapped on it and the engine cut out . I was even able to get the engine to completely shut off by tapping on it. WOW I hope that was it. If so thanks for everyone's help.
check out the link to a video of me messing with the relay.
https://youtu.be/k7SD4MSw4sg

[crazyfox]

now does anyone know if autozone or advance or pep boys carries this and what brand and part number I need? ford shows it obsolete

[crazyfox]

so I put a new eec relay in and it will act up if you tap it hard enough with the screwdriver. I have to use a lot more force to make it do it compared to the old one. i guess if you tap it hard enough the contacts lose contact? maybe the 30 year original one's contacts werent hoding as strong? I don't know, I have had it running for 10 minutes so far and it hasn't died (still a little skeptical if this is the resolution.)I checked the contacts on the plug side of the eec relay (they are tight and look fine), I sprayed them with electric parts cleaner anyhow.) I also wiggled the harness around that plugs into the eec relay and all is fine. Time will tell I guess

[Walking-Tall]

I was about to suggest Rock Auto, but now I see you got and installed one, but if movement or tapping still reproduces the problem, I'd suspect the wire/s going into the relay plug's condition, being broken or having come apart inside their insulation near there. A new soldered and shrink-tubed pigtail there might be peace of mind.

For reference/checking/troubleshooting, wires out of EEC power relay plug, outta the Haynes manual:
- red w/light green - from ignition
- black w/orange - from 20ga blue fuse link G and to ECA
- red - to ECA and to fuel pump inertia switch (onto fuel pump relay and fuel pump)
- black w/light green - to battery negative and a multitude of places (see diagram)

[vintageracer]

30+ years ago I had a then 4 year old Ford 4x4 Pathfinder E350 V8 Van that would run for 10-15 minutes and quit. Let is sit for another 20 minutes and it would again start right up and run another 10 minutes or less and QUIT! I did all the same work you have and replaced all the parts you did. No change to the quit running condition on my van. While the van did not have a lot of miles it did have a lot of high speed idle hours as it was previously used as a "Treater's Van" on Frac jobs in the oil field where I worked at the time. Took the van to the supposed 2 "Best" Ford techs in Ft. Worth Tx. They could not fix it either!!

One day I was sitting there STARING at the engine wondering what the hell it could be as the complete fuel system and ignition system was new I then found one of the wires to the distributor buried under the carburetor that was missing 1 inch of insulation on the wire. The wire was not grounding or touching anything just missing the insulation. I cut the wire, properly spliced the wire (solder/heat shrink), started and drove the van. PROBLEM SOLVED! Van ran PERFECT after properly splicing the distributor wire and never quit again.

Whatever type of wire insulating material Ford used as the extruded coating on their wire in their wiring harness did not like heat very well and easily cracked and in some situations fell off the wire over the years of heat cycles. GM never had this problem. Go look at any 70's and 80's Ford car/truck wiring harness's and you will see the condition of the wire insulation ALWAYS looks bad, is usually cracking and sometimes the insulation is missing altogether.

Apparently Ohms Law V voltage = I amps x R resistance really does work. In my case the heat of the engine would cause resistance to build in the one wire missing the 1 inch section of insulation therefore causing the resistance in the wire to overcome the amps and cause the voltage to drop to 0 or a voltage that was not able to run the ignition system at the distributor.

I am not suggesting you do have this exact problem however I suggest you might want to look very closely your ignition and starting system wiring. You might have a cracked wire, weak connection at a terminal, a wire missing insulation or as suggested above a Bad New ignition switch. Given the fact that your car will immediately start after resetting the ignition switch and system wiring should give you a great place to "Start" (Pun intended) your wire harness review.

Over 3 months of headaches and countless dollars spent Parts Swapping by me and others trying to fix the problem instead of working hard to properly diagnose the problem that ultimately revolved around something as simple as a 1 inch section of wire missing insulation.

That's the way it always works when trying to fix a no run problem on a car or truck. It always ends up being something SIMPLE!!!

Something you might want to consider.

[crazyfox]

so I put a new eec relay in and it will act up if you tap it hard enough with the screwdriver. I have to use a lot more force to make it do it compared to the old one. i guess if you tap it hard enough the contacts lose contact? maybe the 30 year original one's contacts werent hoding as strong? I don't know, I have had it running for 10 minutes so far and it hasn't died (still a little skeptical if this is the resolution.)I checked the contacts on the plug side of the eec relay (they are tight and look fine), I sprayed them with electric parts cleaner anyhow.) I also wiggled the harness around that plugs into the eec relay and all is fine.

[crazyfox]

so after 15 minutes of running it died. when i tapped on the side of the new relay with a screwdriver I could here the fuel pump reprime and the car started right up. this is killing me, what the heck!