It's interesting that people who presumably like computer are so negative
about their use in automobiles. It's kind of like the local boy who does
good and then nobody in town can be found who has a kind word to say about
him. My, my, my. I'm somewhat amused since when I was in the position of
working on the first computer ignition systems (back around 1976 or so) I
was in complete agreement with you. Many of the ones I saw were fried and I
didn't really have any means to determine what was wrong. The 12 volt power
would disappear into a wire loom and into a computer control or igniter
module. There would power to the coil but no spark. There were several
makes of cars that seemed especially susceptible to ECM (electronic control
module) failure. Seemed like a bad idea at the time. As time passed the
modules became more reliable and the test procedures became more familiar,
I began to appreciate the fact that for ignition purposed, a computer is
well-suited for making the rapid adjustment in timing to suit driving
conditions. Also being solid state, it was well suited for maintaining
those adjustments over the life of the vehicle.
The accuracy and effectiveness of a points and condenser operated ignition
is dependent on the condition of:
The timing chain (drives the camshaft which drives the distributor)
Point cam (condition and lubrication - most people don't lube the points
cam)
Spring tension of the points (weak spring will cause point bounce)
Advance Mechanism (vacuum or centrifugal)
Distributor shaft and bearings
The deterioration of any of these components deteriorates the ability of
the points to effectively saturate (charge) the ignition coil. Even when
fully operational the ability of the typical points and condenser to enable
the coil to throw an effective charge across the plug gap is marginal. A
typical electronic ignition throws about twice the voltage to the plug.
Both Bernie and Pippi mentioned the relative costs - there is some merit in
what you say but you have to compare apples to apples there. Points and
condensers are considered standard maintenance items for the vehicles that
use them. They are often replaced at standard intervals. There really isn't
a standard replacement interval on an ignition module. There is no reason
it should not last the life of the car. That they don't always is a matter
of relating to the unfortunate fact that all things can break. But like
most electronic components, if they fail it is sooner rather than later. -
That is, a new component will fail early in it's life rather than later as
mechanical components do.
I'm just surprised that your computer curiosity hasn't driven you to study
and embrace these systems as something that you would understand, tinker
with and perhaps improve. Computer systems on cars have a self diagnostic
mode. They produce error codes much like BIOS beep codes. They are
electrical pulses that can be accessed through the diagnostic connector
using an analog volt-ohm meter. You really aren't completely dependent on
the $50,000 diagnostic machine.
I think the biggest improvement would be for there to be the development of
clone or generic ignition systems. That would drive the module price down
and stimulate the development of universal troubleshooting tools and
procedures. That could satisfy your desire to "do it yourself". As it is,
it is still not beyond your ability if you can get past the fact that your
old points and condenser systems are gone for good.
PS. Pippi if you have that news article about the cruise control causing
the
accident you mentioned, I'd be interested in reading it -
Dave
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