2.3L ('83-'97) Hard restart issue with distinctive pattern

[ShhhhhDougsHere]

@turner I wish you the best.

 

[ShhhhhDougsHere]

Just had a thought.
You wouldn't need a tow if you was to just drive into your back yard and start doing donuts until it dies.
LoL.

 

[turner]

No backyard either! Unless I want to drive it off a cliff into the creek.

I've gotten these symptoms to show up while parked/idling over the past week, I'm sure when I have more time to sit and hold the accelerator pedal down I can make it happen.

 

[ShhhhhDougsHere]

@turner Once again I wish you luck brother.

 

[turner]

Alright, still chasing this fault. Confirmed the coil is not the issue. Original coil measures good in all voltage/resistance tests (from manual) in running and symptomatic conditions. Due to an ebay error I now have 3 motorcraft coils . Went ahead and installed a fresh NOS one anyways. Cleaned all grounds, no issues there. Ground resistance from battery to distributor housing is near zero.

Confirmed there is no pulse 12V signal to the injectors while symptom is present. The fuel pump does not buzz when ignition is turned on. Confirmed both EEC and fuel pump relays are behaving correctly.

Tested voltages at the ECU connector (unplugged), and confirmed it gets 12V constant, switched, and good ground. The PIP pulse signal however was flipping between 4V and 5V, instead of 0V and 12V. Might be that my digital multimeter can't read fast enough and is averaging, or might be weak PIP signal of some sort?

Confirmed the resistance of the PIP wire from TFI module to the ECU is near zero. So it's not a wiring issue.

So at this point I think I need to read the PIP signal voltage while the truck is running and while the symptom is present to see if there's a difference.

I just replaced the TFI and trigger coil with NOS Motorcraft parts, so it doesn't seem very likely that I'd be unlucky enough to suffer an original part failure AND a replacement DOA back to back.

The symptom is also no longer heat related. It'll happen when the engine is dead cold, sometimes. It runs happily until I shut it off, hot or cold, and then it won't restart. So it doesn't make sense to me that any of these components are being affected by heat. There's something about the transition from running to powered down to starting that is causing this.

I suppose it could be the ECU, but want to make sure it's getting a good PIP signal before I go there.

 

[ShhhhhDougsHere]

@turner love the fact that you posted an update.

Sorry I was wrong about the coil.
Yes I can admit I was wrong.
And I'm so sorry I sent you down the wrong path.
Hopefully you do figure this problem out.
Keep trying I'm sure you'll figure it out.

 

[ShhhhhDougsHere]

@turner do you have a EVTM for your truck?
If you don't know EVTM stands for:
Electrical and Vacuum Troubleshooting Manual.

If don't have one they can be found on eBay.

 

[ShhhhhDougsHere]

@turner I just looked on eBay and found this:

 

[turner]

Thanks Doug, I do have the "Engine/Emissions-Diagnosis" manual which covers all the probing tests, that's what has pointed me towards testing individual pins on the ECU connector, etc.

The coil was a reasonable guess, good to rule one more thing out.

I always come back and post the resolution... nothing worse than finding an old thread where the OP has your exact problem and didn't return to share the solution.

 

[ShhhhhDougsHere]

@turner I agree it really sucks when you find a thread like you said that has your exact problem and the original poster does not come back any tell everyone what they figure it out.

 

[turner]

Today's updates:

25ohm resistance between TFI module mounting screws and neg battery terminal... possibly the module isn't getting a good ground? It appears to happen via the tiny tiny screws going into the distributor body, and it doesn't help that it's being held away from the body with thermal paste.

On the rear ground strap that goes to the firewall, I found a separate ring terminal sharing that bolt on the firewall, but with no wire coming out. So we have an orphaned ground terminal. Probably not the source of an intermittent fault... but I should figure out what is supposed to be grounded there anyways.

I went ahead and ordered a new battery and pos/neg cables. The battery appears good, but it's at least 4 years old and I know batteries can do funny things that don't show up on a voltmeter.

 

[SenorNoob]

I'd add a ring terminal ground wire to TFI mount. At least for troubleshooting purposes. Probably permanently. Especially if it works.

 

[ShhhhhDougsHere]

@turner Seems like a lovely ideal to me.

 

[turner]

I'd add a ring terminal ground wire to TFI mount. At least for troubleshooting purposes. Probably permanently. Especially if it works.

I do have an alligator lead clipped between the dizzy body and batt neg while troubleshooting. But I can't figure out a way to run a additional ground to the actual TFI module. Maybe I need to back-probe the ground pin on the TFI connector.

The screw bores in the body of the module aren't big enough to fit the factory tool + a wire. I got a ring terminal crammed down there, but then couldn't tighten the screw. And I have to imagine you wouldn't want it between the module and the distributor, given the trouble Ford went to with thermal paste to get full heatsink.

 

[SenorNoob]

I understand what you saying. Maybe file down a ring terminal enough to get it on properly?

I've seen lower profile ones used for exactly that situation in industrial electrical cabinets. As for where to buy one, not a clue. I'd try to cut one down to fit. If the alligator clip is working, could you put a ring terminal anywhere else on the distributor? Just to throw out an idea...