Puzzle (of the automotive and electronic type)

fiddling

Paul,

2) do you connect the timing light in series or in parallel with the secondary?

If you connect it in series, then I have info for you...

I have seen this happen several times, if there is a fouled plug with leakage, it can cause that cylinder to mis fire because the spark never jumps. I discovered one day by accident, pulling the wires one by one to see which plug was fouled. If you pull the wire off a bit but leave it close to the plug so that a spark jumps from the wire to the tip of the plug, it can make even a fouled plug fire. I had a fouled plug and if I held the end of the wire near the plug, the engine would smooth out I think the theory is that the leakage causes so much damping to the sec that the voltage can never build enough to jump the gap. But if you then insert a gap, the secondary can now build up energy and once it jumps the new gap, it will jump the other gap as well. If you are having all the plugs mis fire, then you may have leakage in the distributor to ground and putting this gap in series with the secondary works as described above. You may have an arc track to ground someplace. Did you try a new dist cap and coil?

Mark

ch

at

ly

ith

Can you leave the timing light in place permanently?

On Mon, 13 Feb 2012 17:37:35 -0800, "Paul Hovnanian P.E." put finger to keyboard and composed:

...

Chryslers of that era used inductive pickup electronic ignition systems. You should find them at the wreckers.

- Franc Zabkar

are

ction

It could load the HV, preventing parasitic arc-over. It could be doing all sorts of things.

Paul needs to fix this, so we know the answer!

-- Cheers, James Arthur

Resent.. was sent yesterday, apparently lost in the ether (not showing up at the Goo).

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 not be 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 .............

Nah! this is the automotive industry. Skin a dime.

In my days in the automotive business, it was "skin a _penny_" ;-) ...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

Having supplied analog IC's to several automotive suppliers over the years I can state that for under hood applications every part was required to be tested at +125C and -40C. And, yes, they expected a discount in price from the low grade part tested at room temp only. Art

These days it's 'Skin the consumer.' :(

In the '60's, automotive was tested to +140°C/-40°C. ...Jim Thompson

That's interesting. Even MIL parts only required 125C. Art

message

Automotive, at least in my era, asked for +140°C or MORE. The difference may well be that, today, under-hood temperatures are lower... due to improved engine efficiency... which reminds me:

I ran onto some trivia, but can't find my way back to it :-(

It said, since ~1980, if we keep a constant weight and horsepower car, mileage (thus efficiency) has gone up 60%. Unfortunately (?) we now demand heavier (and safer) cars with a lot more horsepower. ...Jim Thompson

That's so last century. Now it's "skin the taxpayer."

to

Who do you think pays all taxes, in the end?

to

IMO.

About half the consumers.

The others don't even pay sales tax? Property tax? For license plates, or driver's license?

Perhaps you think people should pay nothing for services used?

Shame it doesn't extend to quality PCBs, hardware, and connectors.

Inflation :-)

-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)