Puzzle (of the automotive and electronic type)

Most common problem I've seen with these is intermittent opens in the trigger coil, Excessive reluctor to pickup gap or damaged bias magnet.

The newer MSD (Multiple Strike Discharge) units will get you a bit better combustion. Instead of one spark per cycle, this throws a burst. Just for sake of discussion:

I lost one of those on my '77 LTD. It was a wirebond inside the potted module :-( ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

I actually did wind (and re-wind and re-stack) the original until I got it the way I wanted (it is gapped). Then a company in Arizona City made the pre-production units. But Ford balked... it cost ~$1 more than a conventional approach with a tranny just doing points duty. But it outperforms a conventional ignition hands-down... it'll blow oil out of the plug gap ;-) I even demo'd a version that would multi-fire at low RPM's to up burn efficiency. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

I had that ~1972, but Ford wouldn't spend the extra $1 :-(

Ford's never had a reluctance issue, just open pick-up coils. ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

My old Toy truck had a similar problem with the ignition. It would go from running fine to running like crap and back again. Long story short - a new set of HV plug wires had it humming happily and 2 more mpg to boot. Art

John Larkin used a "witches brew" of acetone & paint thinner for unpotting, AIRC. Check with him for the proportions/brands/etc.

Ed

Greetings Paul, I've had two cars with this type of ignition that were failing intermittently. The first was Pontiac with the HEI ignition. The module sat in the distributer. It turned out to be heat related. For some reason the module would get hot and fail and it wasn't just engine heat. I would mess with wires and such and the thing would cool down and the car would start. So it seemed like something I was doling was working when it was just a failing module. I replaced the module and that fixed the problem. The second car also had the reluctance wheel type ignition and it would just die. Any time, without any kind of pattern. When I replaced the wires, rotor, cap, and plugs it worked fine for a couple weeks and then started crapping out again. One day it died while I was on the freeway and in desperation I tried turning the distributer in the hope that maybe it was timing. The car started up. And ran sorta OK but the timing wasreally advanced. Setting the timing properly would make the car die whenever it felt like but with the timing advanced it would always start and run. Thinking about why this would be it occurred to me that with the ignition advanced less energy was required to make the spark jump the spark plug gap than when the timing was closer to TDC. So I thought maybe the spark was going to ground somewhere. Looking at the distributer shaft with the new rotor off and using a magnifier I could see a little spot where maybe sparking was happening. To confirm my theory I put the timing light on spark plug wire #1 and with the timing set properly the timing light wouldn't trigger. But with the timing light on the coil wire it would trigger no matter where the timing was set. Putting in yet another rotor, this time a different brand, fixed the problem. As far as building your own electronic points replacement, there used to be available kits to convert points igntion cars to electronic igntion. I bet there still are, and I bet could be used to replace your setup for less than $350.00. This outfit:

sells kits for points replacement for all sorts of cars. Maybe you distributer will be close enough to the old points style that one of these kits will just be a bolt on fix for about $60.00. I just googled points replacement so I don't know anything about the company that makes the Hot-Spark system. Eric

Right. But how is my cheap Sears timing light fixing that (only a connection to coil secondary needed).

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
What if no one ever asked a hypothetical question?

I'd bet there'd be a Bosch unit that would couple directly to your reluctor dissy.

There are some pocket books (like a little bible, thin paper etc) mad by Bosch that had ALL the info on Bosch stuff. "Bosch Automotive Electronics Handbook" or similar name. One of those books would help you a great deal if you could find one (or download??).

good luck.

Intermittent problems are like that. I sometimes assign causation to coincidence, too.

--Winston

On a sunny day (Tue, 14 Feb 2012 18:43:24 -0800) it happened "Paul Hovnanian P.E." wrote in :

A fun answer would be: "leave your timing light connected".

It could be flash-over inside the module, and the timing light perhaps changes capacitance and so in a way secondary voltage peak. Or maybe its loading does that. Then one disconnected it may run for a while until a carbon path burns and it fails again. A couple of pF HV cap, could fix it (for a while?). This module, inspect it for cracks, moisture will get in and cause failure.

Else call some car scrap yards ...

That might burn it up. In addition to keeping it intact for its intended use as a tool, I need it to get this car started.

I didn't see any. But that doesn't mean they are not there.

The carbon tracks explanation might be the best I've heard yet. I can't think of a component that would self heal.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Power is an aphrodisiac. 60 Hertz more so than 50.

[snip]

Its worked too many times (several dozen) for it to be a coincidence.

The ignition is dead and I can play with it for hours (cranking and fiddling until I risk killing a deep discharge battery). But the timing light will 'fix' the ignition within a second or two. Every time. That's what makes this interesting.

I know what part has to go, so this thread isn't so much about the repair as it is about the diagnostic.

In that sense, I'm sort of like Dr. House. The patient is dead. I still want to know why. And I've got a shitty personality, too. ;-)

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Our bombs are smarter than the average high school student.
At least they can find Kuwait. - A. Whitney Brown

Is the timing light the clamp-on-spark-wire type? If so, maybe your first bet is to replace the spark wires ??:-) ...Jim Thompson

--
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
I love to cook with wine.     Sometimes I even put it in the food.

It dumps some coil energy and provides a capacitance. Might seem small, but transformed to the coil primary that can be quite a lot. Did you try hanging a cap across the primary?

--
Regards, Joerg

http://www.analogconsultants.com/

The timing light acts sort of like a zener, right? No current until some particular voltage level is reached. Maybe that's a clue.

Ed

Its on my things to try list. The truck is parked right now. I'm digging through my junk box for an old points condenser (its been years since I've had a vehicle with points).

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
------------------------------------------------------------------
Klein bottle for rent -- inquire within

I don't know what's involved as far as where the module is located physically or electrically in your particular vehicle model.

I realize that you stated the coil still has 12V, but that may be that's not what's being interrupted. You didn't specifically state that you observe this problem in your garage or driveway, or when actually driving the vehicle, or both.

When I encounter a problem which acts just like turning the key off, I examine the key switch very closely, and if I can't actually confirm that the key switch is not the problem (bypass and test driving or thorough testing on the bench), I'll replace it. I would highly suspect the switch in a 30 year old vehicle.

Of course, many yards/meters of old wiring and moisture compromised connector terminals are always worth consideration.

I'm supposing that the timing light used is not an inductive type. The air gap between the rotor tip and the cap electrodes is intended to increase the intensity of the spark at the spark plugs, so adding an old style timing light (springy end poked into the coil output well) in series with the coil HT wire could be having a similar effect, maybe. I'd definitely want a suppressive wire core HT lead there, not the impregnated synthetic strand type of HT lead.

The module could very likely be developing a intermittent fault, but I would expect an internal component fault/breakdown problem to be sensitive to different environmental/ambient temperatures, so you might try placing it in a freezer, and also a hot box heated with a heat gun or similar method.

Trigger coils located in distributors generally stop working altogether when they develop an open circuit fault, IME.. but a possibility exists for intermittent OC faults in the trigger coil leads and associated connections/wiring.

Building a reliable ignition module (capacitor discharge possibly) can be a serious undertaking considering the extreme enviroment in an engine compartment. I believe ignition module makers utilize a superior grade of components to be used in these sorts of products, not just ordinary catalog parts, IMO.

-- Cheers, WB .............