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Author Topic: Broken down!! Ignition module or??  (Read 4067 times)

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Offline Mac

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Broken down!! Ignition module or??
« on: November 21, 2019, 10:03:29 PM »
Was driving to work today, and about halfway there, (point of no return, I guess  ;)), it started sputtering and faltering and
stalled out a bunch of times.....

I limped it to work by popping it into neutral many times, driving with two feet trying to keep the revs up...
Had to restart it a bunch of times while coasting...
Got stuck about 4 blocks from work where it would not restart!  A few minutes later it fired and up and I sputterly managed
to get there!!
I basically coasted it into my parking spot at work when it stalled for the last time...

Every time it happened the tach would drop right to zero...   Even though it was still sputtering and surging...

Classic signs of a failing ignition module right??

At around 11am, I went out to see if it would start, and it fired up and purred like a kitten!!!
For about one minute, then died like I'd turned the key off!!

Waited a few minutes...  Tried again...   Same thing!!   Ran about one minute and then shut off!

Totally classic failing ICM right??

Well!!  I've always carried a spare just in case of this sort of thing!!!   Perfect!!
After work, I swapped out the ICM for my spare, and it fired right up!!
Let it run for about 15 minutes in the parking lot and it idled like a dream the whole time!
Locked up the shop, got in the car, texted my girlfriend that the car was fixed, and that I
was on my way to her place!!

The second I hit "send" the car died just like I'd turned it off!
Would not restart...  Got a couple of hiccuppy sputters, and that's it!!

So!!!   What do you think??   If not ICM, what else would cause these symptoms??

I should mention that the spare ICM I installed was an original AMC part that would be about
37 years old now....   And I honestly don't remember where or how I obtained it!!
Pretty sure I wouldn't have thrown an unknown module in the trunk as a spare if I didn't know
for SURE that it was functional, but it was so long ago, I really can't remember!!
I guess there's a chance it's faulty too!!

I'm going to order a new replacement, but I'm wondering if anything else might have similar
symptoms??   Ignition coil maybe???
Haven't had a chance yet to peruse the TSM....

Oh...  I maybe should mention, that it's the yellow ICM with 3 connectors...
1982 only, I seem to recall....
The computer has been bypassed...  No feedback carb...
Large distributor cap conversion...
Original style coil and connector...


Offline amcfool1

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Re: Broken down!! Ignition module or??
« Reply #1 on: November 21, 2019, 11:41:12 PM »
Coil maybe?

Offline mudkicker715

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Re: Broken down!! Ignition module or??
« Reply #2 on: November 22, 2019, 02:43:49 AM »
This does not scream icm.

Manitowoc WI

Offline Mac

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Re: Broken down!! Ignition module or??
« Reply #3 on: November 22, 2019, 07:14:06 PM »
What does it scream??   ;)

It ran one minute again this morning....
Had it towed home after work...   It ran less than a minute up the driveway and
died halfway into the garage...

Going to be probably mid-week before I get a new ICM...
But in the meantime, I'll check all the ignition circuit wiring and connections, and
I think I have a new Flamethrower coil around somewhere that I can swap in to
see what happens!

What really sucks is, that this is my daily driver!!  :(

Offline Draekon

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Re: Broken down!! Ignition module or??
« Reply #4 on: November 24, 2019, 09:53:21 AM »
The tach dropping to 0 does sound like the coil or ICM is failing.

However, I've had the rest of the symptoms you describe occur when crap in my gas tank got sucked up and caused my fuel pump to start to fail. I can't explain why letting it sit would help, but it did. Replacing the pump and installing the prefilter fixed my problems

Offline Mac

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Re: Broken down!! Ignition module or??
« Reply #5 on: November 24, 2019, 07:30:48 PM »
I've had your symptoms too, way back when I first got the car!!

The fuel pickup sock would get clogged up, and letting it sit for awhile would allow the crud to settle back
to the bottom of the tank...
Solved that by dropping the tank, cleaning it out as best I could, removing the disintegrating sock strainer
and installing a prefilter like you did!
Used a clear filter so that I could keep an eye on it, and I went through about 5 filters in the first year
before it started to stay clear!!

In this case, though...   The prefilter is still clean and full of fuel...
So I'm ruling out fuel pump as it doesn't even sputter like its running out of fuel, it just dies instantly like
it was turned off!!

Small update:

I managed to find a brand new ICM in my parts pile that I bought in 2011 (believe it or not!) when
Rock Auto had a wholesaler clearance going on!!  I'd completely forgotten!!!

Before I installed that one, I tried to start the car, and got nothing...
Installed the new one, and it fired right up!!

I was so excited!!  For about 4 minutes!!  ::)   Died again...
Pulled a plug wire, checked for spark...   Nothing....

SO....  The ICM is no longer my main suspect....
Now I'm thinking coil...   OR...   The pickup coil in the distributor??

I recall years ago having an issue with a pickup coil and it was huge pain to diagnose!! 
But replacing it solved everything!!

The TSM mentions a diagnostic procedure for the pickup coil, but I'll be darned if I can
actually find the procedure in the book!!

Doing a search here found a mention of doing the pickup diagnostic, but not actually
how to do it!!
Anyone done it???

Offline MIPS

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Re: Broken down!! Ignition module or??
« Reply #6 on: November 28, 2019, 01:06:29 AM »
If I recall, the vehicle's TACH is generated from the ICM, which derives it from the distributor pickup, plus timing retard if applicable.

I can't remember if on Duraspark pickups if it was an active or passive hall effect sensor but it should literally just be a coil.

It really sounds like a thermal or intermittent fault which is really frustrating to nail down. I'd test with another coil first if you could and if it persists, replace the pickup.
« Last Edit: November 28, 2019, 01:07:48 AM by MIPS »

Offline Mac

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Re: Broken down!! Ignition module or??
« Reply #7 on: December 12, 2019, 11:24:27 PM »
Update!   Sorry for the delay, for anyone that may be following...

(where the heck did all the members of this board go??   It used to be super
active, and now only the original diehards??   Weird!!)

Anyway...  The update...

So pickup coil, or ignition coil??  Tried a used coil I had...  No spark...
Tried original coil again..  Spark!!   And It ran again for one minute...
Must be pickup coil??
Didn't have a spare pickup coil!!
Ordered one from Rock Auto...   Express shipping to get it to Canada in two days!!
Part came in totally wrong!!  Right box, wrong part...
It would take over a week or two for them to fix their mistake...
So I ordered a lesser brand locally and only had two days to wait...
In the meantime...  I read a few Ford forums about Duraspark systems
and a few mentioned the ignition feed passing thru the starter solenoid, and
possible internal shorting in the solenoid causing problems, so while
I was waiting for parts, I decided to swap out the solenoid for the heck of it since
I had a spare!
I'll be dambed if the car didn't run like a dream!!!
I was too scared to take it out for a test drive on that dark, snowy night, but I ran
it for over a half hour in the garage without so much as a hiccup!!

Next day, I got the new pickup coil, and decided to swap that in to rule it out as
a possibility, and I once again got no spark!!!   WTF??

Crappy made in China parts??   The air gap DID seem a bit excessive!
So I swapped the original pickup coil back in, and STILL no spark!!

Swapped in an old OEM ignition module I found in the basement, and got spark!!
And then didn't!!!   WTF??
Then, (like I should have in the very first place) I started going through the diagnosis
charts in the TSM!!   LOL!!   Yes...  I'm a dumass, but WAS working alone at times
without a helper to turn the key while I was checking stuff under the hood!!
Anyway...   The diagnoses led to either a failed ICM, faulty ignition resistance wire,
or bad coil...
So I tried a new coil and once again got spark!!!  YES!!!
Mounted up the new coil in its bracket all permanent like, and got no spark again!!
Turns out in the end...  The ground/green wire in the horseshoe connector feeding
 the coil was broken-ish/intermittent!!
So now...   I'm not sure what caused the initial failure, the intermittent failure or what
parts were faulty!!
Many of the parts are now new, but not sure if they were even needed in the first place!!
I think the coil wire probably fatigued from removing and replacing the coil connector
about a hundred times that weekend, so I'm not convinced that it was the original source of the problem!!

The coil (an Accel high performance coil that I installed when I did the big cap upgrade)
tested 200 ohms less than the low spec for the coil in the TSM...
I can't imagine that 200 ohms would make a huge difference when the spec is between
7500 and 10,500 or some such thing??
Not sure if the starter solenoid might have over volted the ICM or coil and overheated
one or the other??  Or if that's even possible??  A few Ford guys swear it's happened!!

Anyway...  With a new starter solenoid, stock coil, an OEM AMC stickered 30 year-ish old ICM I drove
it to work for a week, and it worked okay, but seemed to sputter every now and then,
and didn't start nearly as quickly as it used to!!

Remembering that I probably gapped the plugs larger than stock when I installed
the hotter coil, I pulled them and found them pretty well worn with a gap of almost .050"!!!
So I replaced them with new, gapped to .035" and she purrs like a kitten again!!!

Offline amcfool1

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Re: Broken down!! Ignition module or??
« Reply #8 on: December 12, 2019, 11:37:28 PM »
hey, good for you. that coil connector wire frayed on me as well, took a lot of headscratching to figure it out. good luck, gz

Offline vangremlin

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Re: Broken down!! Ignition module or??
« Reply #9 on: December 13, 2019, 01:24:44 PM »
Glad to hear you Eagle is running so well!  May you have many miles of carefree motoring!!
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline Mac

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Re: Broken down!! Ignition module or??
« Reply #10 on: January 07, 2020, 11:14:21 PM »
Thanks guys!!   :)

Sorry for the delay in updating!!

Car is still running okay, but I'd swear not quite as smooth at it used to!
And still doesn't fire up from cold as instantly as it used to...
The tach seems to twitch every now and then which I don't remember it doing before...
Noticeable mostly at idle or at constant highway cruising speed...

I find myself watching the tach more than the road these days!!!   :-[

Could it be due to the made in China replacement coil?

I'm thinking of rigging up a secondary coil mount so that I can quickly plug and play
the current and previous coil to compare results....
I think the old coil worked much better!!

But...   It's winter now, and it really sucks to be stuck at the side of the road in the snow!!
So I just might wait until spring to experiment!!   ;)

Offline charlie D

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Re: Broken down!! Ignition module or??
« Reply #11 on: August 13, 2020, 07:58:38 AM »
Hi Mac,
Curious at the end result of your coil vs coil test. I just acquired an 86 Eagle and have been reading the forum to learn as much as possible before throwing parts at it and making more trouble than I started with. I have chased poor quality coils in the past on a 428 Ford. The factory mount is on the front of the engine and when they get hot, they fail. Cool off, work again. Problem is that some of the coils are not made to specs and won't tolerate the heat. Really need to look for ones made here or Mexico for the best chance of success. My Eagle has a hard start and occasionally stalls when I back off the throttle at slow speeds, like in a turn to park. Anyway, it had not been serviced since 2017, so I will do the basic fuel filter, plugs, wires, dizzy cap and rotor so I have a base line to start. Hope it isn't the carb as the whole Gronk conversion has a lot of mixed reviews.
Charlie D

Offline Taylor

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Re: Broken down!! Ignition module or??
« Reply #12 on: August 13, 2020, 01:09:45 PM »
Not sure how to test the factory ignition module. It was a ford unit, same as the ones they used in their 6I, I believe.
I bought a new one on rockauto about 10 years ago. My OEM factory coil was still working when I pulled it about 8 months ago.
I have since replaced the entire thing with a GM style hei. I also did the ECM Test bypass when I replaced the bbd with a chinese made copy a.k.a. Gronk carb. Have had a few problems with it. I don’t believe the ethanol added to our fuels is any good and I think that is the source of my problems with it. Others have had major problems with them. If you can find a true motocraft 2150 and rebuild it you’ll be better off.
Eventually I will go with something like the sniper fuel injection.
2010 Toyota Rav4 Daily Driver (better mileage and family beater)
1985 AMC Eagle Limited Wagon 🖖🏼🦅 Eats Audi quatros for breakfast😎 Official Member of the Land Rover recovery team.
2005 Ford Excursion 4X4 wife's around town daily driver and family pack mule.
2020 Honda Africa Twin for whatever...

Offline Mac

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Re: Broken down!! Ignition module or??
« Reply #13 on: August 26, 2020, 11:14:47 PM »
Hey Charlie!

Sorry I haven't updated this thread...
I did in fact do a coil vs coil test!

Mounted the old coil that I'd been using since I built the car to the shock tower
with it's own wire to make things quick and easy for a "side of the road" change
if need be...

I'd insert a picture here, but I honestly can't remember how to do it!!   :-[

That's one nice thing about the kinda cheesy horseshoe coil connector!
No tools required!!

In the end:   The car did start a bit quicker....   Idled a bit better...
The tach didn't jump around as much....

BUT!   It really doesn't seem QUITE to back to the way it used to be....
Certainly better than the new Chinese coil!

I'd like to find a new replacement for the Accel coil that I used to run, and
performed flawlessly for years, but apparently it's been discontinued!! 

I'm currently STILL running that same Accel coil on the testing bracket,
but it occurred to me that it has almost 100,000 kilometres on it now!!

That might be an issue??  LOL!!

Offline charlie D

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Re: Broken down!! Ignition module or??
« Reply #14 on: August 31, 2020, 04:05:41 PM »
Mac, glad the switch back to the old coil made things "better". From what I am learning on this forum and looking at the repairs manual, our coil does not need to be something from a high performance manufacturer. In fact, MSD has troubles of their own. As $$ spent goes, a coil is a modest investment. Maybe worth going to your local parts store and look for one made here or Mexico. Thanks for the update.
I did the basic plugs, plug wires, dizzy cap and rotor, a little Gumout treatment to the carb and mine is running well. Now onto the rest  of it--leaky valve cover, electric locks not working, the usual old car stuff! BTW, mine still has the original AMC labeled coil.


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