Self healing component failures

My '77 280Z would do that, but it was the ignition module itself $:-( ...Jim Thompson

Been umpteen years..i think some oil-filled (paper?) capacitors and some electrolytics (notably the older, obsolete wet ones) had that property. Certainly not solid state items (transformers, relays, inductors).

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Remember under the hood it is extremely hot and electrically quite noisy from the ignition pulses. Try to figure out how either could affect performance of this module.

The last time you asked about this, I recommended replacing it with a module from a junked vehicle. I like the idea of monitoring waveforms at various points because I suspect that high voltage pulses are getting into the module and affecting it. At least you would see what was happening right before the engine died. Have you tried asking on internet forums for that particular vehicle/vintage/manufacturer? Who made the module, anyways? It might have been common to more than one vehicle. Was this module replaced with another during the production run? There might have been a weakness that was found and fixed.

I had a similar problem on one of my cars a few years back. It would also just randomly cut out, and refuse to restart, but for minutes rather than days. I too thought that it was an ignition problem, and suspected the electronic ignition module. However, I connected a whole bunch of LEDs to various points in the system, and discovered that when it failed, it was the feed to the electric fuel pump that was going off, and the problem ultimately proved to be bad joints in the fuel pump relay, which had a PCB inside, with its own driver transistor and a few other bits and bobs on it.

Just a few weeks ago, my current car started doing something similar. It would just completely fail to start, even though the engine was warm and had been running just fine only minutes before. But if you left it for a few hours and then came back to it, it would start first flick of the key. Again, I suspected either an ignition or ECU problem as when it was failing to start, it put the engine management error light on, but it turned out to be the fuel pump motor failing to start.

Arfa

This isn't an ECM. Its just an ignition module to replace points ignition.

It has a magnetic pickup which is OK and puts out pulses even when the system is dead. It has +12 in from the ignition switch (connections checked and cleaned). It has a ground (cleaned and an additional ground ran down to the battery/frame ground bolt) and connection to the coil (-). The coil also has +12V through an ignition resistor* (replaced in the process of diagnosis, no improvement). So its a very simple system.

I've caught in inoperative a few times parked in the driveway, so I've been able to check the basic voltage levels and the pickup output**. When I'm not trying to get someplace, that is. More often than not, its a matter of just saying "Screw it. I've gotta be someplace" and just switch vehicles. Fortunately, this is one of my rather large fleet of 4x4s.

**The interesting diagnostic was checking the coil output with the timing light. Putting the strobe on the coil fixes the problem. Every time, within seconds. In fact, the fix is so reliable, I just carry the damned timing light around with me.

I had those symptoms on my Vision TSi, a decade or so ago. It started out as the engine just stumbling, then restarting before the car even slowed. After a while I had to pull over and restart it. Then nothing, for maybe hours. After a dozen trips into the garage and a couple of long walks in the Vermont Winter (I did eventually find some place to call a cab). It finally happened when they were watching it. The flywheel sensor was going intermittent, no RPMs = no gas.

I had that several times on my '78 Ford Granada. I got suspicious of the carb when gas came shooting out of the venturi and spraying all over the windshield. "I don't think that's supposed to happen", said I.

Since a timing light always remedies the problem that points to the HV side of the ignition. In particular the coil to distributor wire. You say you've replaced everything. Does that include all the HV wires, dist cap, rotor, coil, and plugs? All of those together are cheap compared the ignition module.

My old Toyota truck is only 28 years old so you have me beat. A couple of years ago it started acting up by intermittently missing and failing emissions inspection big time. Long story short, a new set of plug wires had things humming again and added 2mpg to boot. Art

Yes. New coil, wires, cap, rotor, plugs. Although this is an all on/off problem, so its doubtfull all the plugs would fail simultaneously.

Agreed. Having ruled out everything downstream of the ign module ... The only electrical effect I can think of is that the timing light added capacitance to the coil output. This got reflected across the coil and "fixes" the ign module. Have you considered going to an aftermarket CDI? This is the first one I found and it's considerably less than the OEM module.

We had one car that kept not starting. The solenoid would click, but nothing would happen. Then, a few moment later, it would work just fine. One day, it was showing the problem, and I got under the hood while a co-worker would try the starter. I put my hand down, and it started up! Looked where I had set my hand, and it was the ground cable to the battery. Loosened the battery clamp, and the clamp fell off the cable. During the installation of the 'new' wiring harness (another long story!) they had put in a too short battery ground cable. Vibration and corrosion had broken the cable inside the insulation so that it was 'just' touching, sometimes. Replaced the cable with much more flexible copper braid and never had problems again!

Charlie

Exactly. I just can't figure out what its 'fixing' and how. And what, left to sit on its own, will fix itself in days/weeks.

The electrolytic cap suggestion has merit. The cap fails under normal loading, but heals itself when left to rest or when the load is increased by adding the strobe light.

Its a puzzle I'd like to solve, even if the fix is just to replace the entire module. Its potted, so its probably a goner anyway.

That's a coil on plug retrofit, if I'm not mistaken. And it still needs an ignition module to drive it. I'd rather stick with the OEM coil and distributor. The Landcruiser setup has a few design features enabling it to work submerged and I'd hate to go to a standard automotive setup not built with rugged environments in mind.

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Try replacing the ignition coil itself.

?-)

You

Aw phooey. You have already done that.

Lucas strikes again, and again! ;-)

That was the first thing I replaced.