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If you were like many of us with "hot" cars
rcwithlime   10/20/2011 3:19:42 PM
we replaced the std mfg's coil with the high output aftermarket ones. Well, you were also supposed to use the resistor to decrease the voltage. If you didn't , you would fry the points, etc.

Object was not to provide too much spark to the distributor and then to the plugs, but to use a coil with enough ummph and "ampacity" to make sure that it provided the spark each and every time. Then, once the spark was provided, it was reduced back down to tolerable levels.

I had done the same thing, saw the same sparks with my wires, burned up points, etc. Back then, there were not a lot of knowledgeable backyard mechanics when it came to electronics. You purchased what magazines touted as better. Unfortunately, if you bought those aftermarket coils used, you did not get the instructions with them, which stated the resitor required and it's p/n.

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Another car stall solved
bellaire   10/20/2011 11:31:01 AM
So here is another one. Back in the 60's a friend had a lovely old Daimler. It would run perfectly but occasionally it would cut out going up a hill with a slight left hand bend.

Cutting a long story short on the 6th or 7th trip to the garage the mechanics could not find anything wrong. They left it running for several hours (petrol was cheaper then) no failure. They opened the bonnet and it ran for another hour then the break through. Remember the days when you changed your antifreeze every 12 months. The garage would tie on a "Bluecol" label with the date. This label had a twisted piece of wire to the bonnet.

It hung down and when gravity and centrifugal force from turning and going up hill was just right, it would swing infront of the air intake and seal it off until the engine stalled. The vacuum would then disappear and the label fall back. The mechanic spotted a slightly dark ring on the label from the air intake!

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Sparky McSpark
Noswad   10/20/2011 9:36:00 AM
Working with older cars can be interesting. I once replaced the ignition coil with one of those super coils and also replaced the spark plug wires. Being the tight wad that I am I baught the cheaper set of wires. I started up the car and it had a little bit of a rough idle. By that time it was beginning to get dark outside. I popped the hood and to my amazement there were little spark all around the engine compartment. It looked like one of those physics experiments where you touch the glass globe and sparks are visible all inside the globe.

I went to the auto parts store the next day and baught a quality set of spark plug wires and the problems was cured. Also, the car had much more power with the new coil and I had to go to a colder set of plugs.

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More Stalling
WaltP   10/20/2011 9:33:27 AM
Had an old  Corvair that I was trying to restore about 20 years ago with a similar problem on right turns.   The motor would sputter and die, but as I coasted through the corner and straightened out, the engine would catch and start going again..  

 It drove me nuts for months.  Changed the fuel pump, checked fuel lines, rebuilt the carbuerator   Changed the plugs, the wires, the points. battery, battery cables....had the "generator" checked.  There wasn't all that much stuff that could go wrong on car from the early 60's

Finally figured out that the mounting bracket for the coil had rotted away.  I was under "hood" and bumped the coil and killed the engine.  When driving, and you took a corner, the coil would tip over and short against the the body.  Once you straightened out there was enough spring in the coil wire to pull the assembly back....and the engine resume running

Unfortunately that was the begining of the end for that car - the frame was rotted and way too expensive to fix....

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loose hose stops the show
failureindesign   10/19/2011 10:37:56 PM
On thing I always marvelled at was under the hoods of my Honda Accord, my Chevy Nova and my VW Rabbit: the care and training of various wires, hoses and other miscellania.

The Rabbit had most things tied down (execpt where the dealer had touched something - like when the dealer REMOVED the emission controls because they made the car "dirtier"!!).

The Accord had everything tied down and is still running great after 20 years.

The Nova ... well, let's be kind and just say they meant to tie everything down but didn't get around to it. Even the ceiling liner fell down eventually.

The Rabbit was still running great when I sold it at 115K. The Nova ran for a few years (died around 145K). But the Accord still runs like the day I bought it (20 years and 156K ago).

LoL Like I always say, "It's all in design!" (And it doesn't hurt to be built in Marysville, Ohio either!  :-)


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Tim   10/19/2011 10:18:07 PM
I am sure that the shock from the spark plug wire was pretty jolting.  As a kid, I wanted to see if the spark was firing in our line trimmer.   The only solution I was to pull the sparkplug hook up the boot and hold both the spark plug and the cylinder block with the other while I pulled the starter rope.  Needless to say the rewind spring engaging allowed me to open my hand enough to drop the plug and vow to never do that again.

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Re: The Case of the Shocking Stall
JimT@Future-Product-Innovations   10/19/2011 1:06:04 PM
Ouch!  I revise my earlier comment about "makes total sense".  A faulty boot allowing a current leak makes even more sense.  Thanks for taking me back to school!

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That’s Shocking!
JimT@Future-Product-Innovations   10/19/2011 12:55:03 PM

Kudus on your diagnostics methods, and your conclusion makes total sense. High voltage from a coil reacting with a greasy hose; I believe it.   And the 2c fix of a wire tie is my very favorite solution to so many of life’s perplexing mysteries.  Sorry you had to have the shocking experience to go along with the discovery!

Charles Murray
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Right-turn sensitive
Charles Murray   10/19/2011 11:27:43 AM
Some vehicles can be pretty sensitive about right turns. A few years ago, my Honda Odyssey believed that the driver side door was opening every time I made a right turn. During the turn, the vehicle's interior lights would illuminate, the "door ajar" light on the dashboard would turn on, and a buzzer would sound. The culprit? A faulty seat belt. Because the seat belt wouldn't retract, it got stuck in the door, leaving a dent on the inside of the door. A plunger switch responsible for monitoring the door status would extend into the dent whenever I turned right, making the car believe that the door was open. The solution: I put a piece of duct tape over the dent. I still carry a role of duct tape in the car wherever I drive.

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The Case of the Shocking Stall
thrashercharged   10/19/2011 10:41:10 AM
It's a little known fact that the high carbon content of black rubber vacuum hoses can make them act as a conductor.  An old mechanics trick to disable cylinders selectively (to isolate which cylinder is misfiring) is to pull the spark plug cables off the distributor, and fasten 1" pieces of rubber vacuum hose between the distributor terminals and the spark plug cables.

The engine is then started (and it'll run because the vacuum hose acts as a conductor), and a ground wire (the old school mechanic would use their grounded test probe light) is run close to each hose providing a less resistive path than the spark plug to ground, thereby forcing that cylinder to misfire.

Yes it works every time.

But back to the point - moving that offending vacuum hose isn't solving the problem but replacing the spark plug wires was.  The guy has a bad cable boot at the offending terminal that isn't insulating properly - probably cracked. This would never happen if the components were in good shape.

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