Would it be safe to say that we have a triggering problem? As mentioned before, after the plug wire was replaced the secondary patterns looked good. Could we have an ignition coil that was failing intermittently? I don't think so considering the pattern didn't freak out with that open plug wire on the engine. EST problem? I suppose that is a possibility, but I'm gonna go with the ICM. Did I mention that this had an aftermarket ICM? A new ICM took care of the problem.
My main point is to bring attention to bad primary triggering and how
that affects the secondary pattern. Experienced driveability techs will see
these problems on an ignition scope and not waste time pulling plugs, wires,
caps, etc... Triggering problems can of course also be caused by loose
connections, corrosion, etc... I did not do a thorough analysis, I did not
scope every wire, check every connection, etc... But I did take a lot of that
into account when using the feel
and the visual inspection. Like many of you, I also want to be sure that I'm
sure that I'm sure... but due to how our industry operates, we can't go to
extreme lengths in all of our diagnoses and keep the shop doors open. What we
can do however, is quickly narrow down the search and then spend the time we
have left with pinpoint testing.
Remember this Vette Opti-Spark ignition pattern?
Do we not have a primary
triggering problem? Of all the possibilities, where would the first place to
look be? Would it make sense to do a complete engine performance diagnostic if
it drove great except for an occasional burp (misfire)? Why not just zoom in on
the problem, and then from there up sell maintenance work? Sure, if you’re
working on a total pile, then you'll be wise to look things over a bit closer
but time is money so we need to work smart.
In the December 1999 issue of Motor Age, Mitch Schneider made the
following
statement in his article titled "The Machine That
Changed The World":
"The service industry, an
industry that has always been a crafts-based
industry, was now being forced to
exist within a mass production model.
Service, maintenance, and repair
were reduced to piecework and the clock
became the ringmaster in a circus
of shortcuts, cutting corners, and
eliminating steps. Quality was
sacrificed in the name of expediency and both
the industry and the motoring
public continues to suffer."
While I understand and agree with much of what he has said, I do think he has made the mistake of assuming that the clock always destroys the quality of service. Maybe we need the clock to weed out those of us who refuse to think... Should the consumers be required to pay for unnecessary test procedures? Would you be upset if your doctor wanted to charge you for a rectum examination when you came in complaining of a sore throat?