Help please - intermittent stall - now solved (I think!)

[gaz]

@Cees Klumper
What color is the replacement Motorcraft Ignition Module (TFI) that you installed?

 

[Cees Klumper]

It's grey, Motorcraft. But installing it made no difference compared to the previous (also grey but aftermarket) one.

 

[Cees Klumper]

Today's update is I replaced the ignition switch on the steering column and both the EEC and fuel pump relays. No change, the engine stalled again 3 times during a 5 mile trip in the city. Started right back up again.
Next attempts: change the fuel filter (long shot) and maybe swap out the distributor?
Dreading a possible bad wire 'somewhere' in the harnesses.

 

[Cees Klumper]

Just ordered a new fuel filter, distributor and coil. Will also swap out the ECU with my 2 spares.
If this all does not address the stalling issue I will start checking all the wires coming and going to the ECU, see if there is one compromised one.
The truck runs beautifully when it runs, then stalls without warning, without any hesitation, in an instant. Sometimes it will 'run on' trying to keep running but failing, until I turn the ignition off. Then it will typically restart right away, although sometimes I need to wait a couple of seconds before it will restart and drive the next 1-5-15-50 miles until it will stall again.

 

[RobbieD]

I admire your persistence, and I hope that you hit the "Aha!" moment soon.

I did unplug the inertia switch but it made no difference, still random stalling.

Just to clarify, I'm pretty sure you would have to jumper the inertia switch plug wires when unplugged; is that what you did?

It just sounds too much like intermittent wiring failure to me, and there's no telling what kind of "repairs" have been done in the past on an older truck.

 

[Cees Klumper]

Hi and thanks - I thought I had unplugged the inertia switch plug and jumpered it, but when I went to put the plug back onto the switch, I found the wire was only in one of the two contacts, and the other end had come out - and the truck ran fine that way? Strange I thought, but plugged it back into the switch. I know the switch does work, or at least it did just two years ago, when I bumped someone's trailer hitch (they were fine, my bumper was not) it did its job, truck would not start until I reset the switch.
The truck is quite original and although it has 245K plus miles, I haven't seen hardly any 'modifications' to any of the wiring, it seems to have all its original wiring/harness/plugs/fuses and so on. It was also always in a very dry California desert climate (Palmdale) and there's 0 rust on the truck, so it's had a fairly easy life so far.
One thing I forgot to check out and just thought of, really a massive oversight on my part and one that I am sure everyone took as a given that I would have done as one of the first things, is check all the fuse connections, both the small ones inside the cabin as well as those larger ones on the power distribution box. I don't know how I missed that simple step, moreover because I've ran into issues with older cars' fuses not making good contact before. So that's now also on the growing list of possible suspects. Hope to work on it again today or tomorrow, for sure over the weekend. I am surviving with my motorcycle but it's not ideal.

 

[RobbieD]

That does sound strange. Power to the fuel pump from the FP relay runs through the inertia switch, and the switch opening (crash or bumped) or being unplugged should keep the pump from running.

Don't give up, and good luck!

 

[Cees Klumper]

Here's today's update. I worked on the Bronco all day - started with checking the codes once more. I had one, in the KOEO mode, stored: number 18. Book says that's " IDM circuit failure or SPOUT circuit grounded". I found an interesting thread on this here, the original poster described exactly my issue (random stalls):

Code 18 random engine stall . 2months of crazy!!

www.fullsizebronco.com

I did the tests that I could understand (much of this thread goes straight over my head, I have almost no experience troubleshooting wiring issues, much less on this era truck):
- tested the spout connector itself
- tested for faulty ground on both spout connector wires - nothing (both had in the many millions ohms resistance, as I understand they should have)
- tested the resistance of one wire (forget now which) that was supposed to have between 20-25K ohms resistance, due to an in-line resistor 'somewhere' in the wiring loom under the hood (a noise suppression resistor, going to or from the coil I believe) - it has 22.5K ohm resistance - so that seems good
- I replaced the not-that-old coil with a new Motorcraft one I picked up yesterday
- I removed the distributor, inspected it, and placed a new TFI module in place of the still-pretty-new Motorcraft one, just for good measure. Re-installed, set timing (with spout connector removed) to 10 degrees advance, and re-installed the spout connector
- I also tested two of the wires going from the TFI to the ECU/computer for continuity - green-yellow ones. They tested out fine but, in the process of identifying the correct wires at the TFI connector, I discovered that a previous owner/mechanic had already replaced the original TFI connector with an aftermarket/different one, since all the wires coming from it were black. I traced the wires to where they had been fused to the original wiring loom and tested each of those connections for continuity, wiggling each one in the process to try and uncover a break in any one of the connections. No luck, they had been done pretty well, with shrink wrap over the joins and that all covered with electrical tape. I did notice that one of the original loom harnesses that about 3 wires from the TFI go into (the TFI connector separates into two bundles of 3 or so wires each, going in a different place in the wiring looms) was missing the last section of 'wire sheathing' (sort of a thin metal foil probably designed to keep out radio interference to the signals going through the wires). I did not have anything to replace it with at hand so left it as-is (after all the truck has been running fine without this random stall problem for almost 4 years I've owned it)

After all that, drove home at the end of the day, all good, until the engine was warmed up well and now I have a different problem: rather than cutting out and stalling altogether, it just misfires bad for a split second: I can see the RPM gauge drop to almost zero and hear the truck stalling, but then it 'catches' itself, tach needle goes back up to where it was and it just goes on running. As I was getting closer to home, it started doing this more and more often - but it never stalled completely, as it did before.

So, definitely ignition related and it also seems highly likely heat-related. I know, the TFI module is sensitive to heat and I could mount it remotely etc, but this is a brand new TFI module, replacing another brand new one. What is at least somewhat encouraging is that, whatever I did (and I manipulated a lot of wires, unplugged and plugged back in a number of connectors etc), it has altered the symptoms at least somewhat. So the 'code 18' is probably the clue to my mystery.

What I now want to do is find someone local to me (Los Angeles, lots of shops here) who is at least somewhat experienced with diagnosing and addressing electrical / wiring / harness / ignition issues such as this one. I spent all day, after having spent so many hours before, and am just out of energy to keep at it. I am not experienced in this type of issue and when I read various forum threads on this 'code 18 issue' it became clear to me that it is not uncommon, and there ARE people with a lot of knowledge and experience and could likely resolve it much more efficiently than I can. I really don't want to sell it in this condition, or junk it, it's too nice for that.

 

[Cees Klumper]

Just read this thread on our own forum here, that's on point. Seems it may be caused by interference coming from coil/spark plug wires affecting the signal/wave form from the TFI/ignition wires going to the ECU. Makes sense, even for a total novice like me. Since I manipulated so many wires/connectors/spark plug wires today, that the influence of those kilovolt signals has not gone away, but has changed so that the problem symptoms have also changed (not gone away):

2.3L ('83-'97) - SPOUT CODE 18 after final assembly, last code to correct : SOLVED!!!!!

Ill preface this, I know what SPOUT is and have already corrected a shorted SPOUT condition with a new Standard Brand DIS, a replacement coil (exhaust) and a wide variety of damaged wires by former owner BUBBA from Mississippi. But alas it has returned unexpectedly after I tampered with most of...

www.therangerstation.com

But, most of this thread I really don't understand. So I really need someone who does this for a living, I am just an accountant!

 

[rusty ol ranger]

There is a 28 (?)k ohm reisistor somewhere in the wireing harness that goes to the ignition coil.

Ive read of that being the usual reason for code 18. My 87 2.9 also throws an 18 but it runs fine so i just left it be because,..wiring sucks.

But that resistor could be causing this. Maybe @RonD can shed much more light on it then i can

 

[Angry Possum]

Dam, seems like you literally tried everything, I hope you find the problem soon. You have a lot of patience.

 

[Cees Klumper]

Thanks for the words of encouragement/ @rusty ol ranger I did, I think/hope, test that resistor, it read 22.5K ohm - so that seems good as the spec I read in one of the code 18 threads said it should be between 20K and 25K ohms.

 

[Cees Klumper]

This hopefully final update. As I was running out of skill, ideas and time (we moved from Marina del Rey/LA to De Luz / Temecula closer to San Diego last week) I took the Bronco II to a garage in Santa Monica that specializes in older mostly muscle cars, first gen Broncos and the like. On the 4 mile trip there the truck stalled twice on me and the idle dropped close to stalling about 15 times so it was getting much worse with every drive, I barely made it in.
After a couple of days diagnosing they called and said they found vacuum leaks between the intake manifold and heads that needed addressing. I said I doubt that's the cause of the stalling but please go ahead. So they put in a new gasket sealing up the intake and also installed a new coolant temp sensor and called that it was ready to be picked up.
So I picked it up yesterday and, fingers crossed, they appear to have solved my problem. On several trips around town it did not falter let alone stall a single time.
They did mess up the ignition timing really badly. As I drove off the engine had practically zero power, adding throttle just made thimgs worse so I suspected they had not set timing with spout connector removed, but it turned out to be even worse than that. And, to compensate for the very poor running as a result of the bad timing, they messed with the throttle body butterfly valve screw, to force-increase the idle. Because of the bad timing the exhaust also became super hot, heating up the passenger floor!
So, I corrected both (I had to take out the distributor and re-insert rotated a bit so I could get the timing to spec, it maxed out against the valve cover before the timing mark even became visible on the timing light) and now the engine is as strong as ever. I did not yet have time to take it on longer test drives but it's definitely 100% better.
If the problem does return I will update this thread again, but I am hoping their smoke machine diagnosis finding the air leak and subsequent work to put in a new gasket etc was the fix.

 

[rusty ol ranger]

This hopefully final update. As I was running out of skill, ideas and time (we moved from Marina del Rey/LA to De Luz / Temecula closer to San Diego last week) I took the Bronco II to a garage in Santa Monica that specializes in older mostly muscle cars, first gen Broncos and the like. On the 4 mile trip there the truck stalled twice on me and the idle dropped close to stalling about 15 times so it was getting much worse with every drive, I barely made it in.
After a couple of days diagnosing they called and said they found vacuum leaks between the intake manifold and heads that needed addressing. I said I doubt that's the cause of the stalling but please go ahead. So they put in a new gasket sealing up the intake and also installed a new coolant temp sensor and called that it was ready to be picked up.
So I picked it up yesterday and, fingers crossed, they appear to have solved my problem. On several trips around town it did not falter let alone stall a single time.
They did mess up the ignition timing really badly. As I drove off the engine had practically zero power, adding throttle just made thimgs worse so I suspected they had not set timing with spout connector removed, but it turned out to be even worse than that. And, to compensate for the very poor running as a result of the bad timing, they messed with the throttle body butterfly valve screw, to force-increase the idle. Because of the bad timing the exhaust also became super hot, heating up the passenger floor!
So, I corrected both (I had to take out the distributor and re-insert rotated a bit so I could get the timing to spec, it maxed out against the valve cover before the timing mark even became visible on the timing light) and now the engine is as strong as ever. I did not yet have time to take it on longer test drives but it's definitely 100% better.
If the problem does return I will update this thread again, but I am hoping their smoke machine diagnosis finding the air leak and subsequent work to put in a new gasket etc was the fix.

Now that you mention the intake gasket i had an escort do that once.

Not to the extent yours was but it would come to a light and die. Randomly run like shit, etc.

Glad you got it figured out

 

[Cees Klumper]

Forgot to mention that the shop also put in a new distributor that I supplied - so the cure might have also been the new pickup module inside the distributor. So it was either the vacuum leak under the intake manifold or the pickup module imside the distributor.