Mechanical vs Electronic - Analog vs Digital

Last year, the questions centered around timing belts and head gaskets.
Mechanical items.

This year, intermittants are rearing their ugly heads. Cars are aging now
and wires and connections are giving out. I would venture to say diagnosis
has taken a turn for the worse.

You see, to humans, mechanical things are intuitive. A lot of non-trained
people out there could mull their way through a TOH (valve job) but how
many times have you heard, "I can overhaul an engine, but I don't get auto
electrics?"

Its always been that way. Whenever you had an electric problem, you went
to a specialist, an automotive electrician, because so few general
mechanics really knew the electrical system. And that was in the "old
days." It has gotten a lot worse since electronics came in.

With the first generation electronics, you had a chance. If you knew a
little about radio or tv repair, it was a cinch. Otherwise, you just
replaced the black box. Back then, black boxes were "discrete"; today, its
one giant integrated "computer". Therein lies the problem.

In order of difficulty, the evolution of auto electrics followed the
course: electro-mechanical, electronic (analog), and electronic (digital).
With each step, fewer mechanics understood the increasingly complex
systems. In fact, today's digital system is so complex, manufacturers' no
longer provide schematics of the black-box circuitry, making it virtually
impossible for even the best trained engineers to really know what's going
on inside the box. The best we can hope for is to understand inputs and
outputs, with the elegant processing becoming a "who cares" event.

Look at fuel systems. In the beginning it was all mechanical. No
electrics to worry about. The epitomy of carbs was the '30s Carter. Fully
adjustable with needle valves for all circuits and even an adjustable
accelerator pump! Carbs became fixed eventually. A nice example of an
electro-mechanical system is the Bosch Jetronic. Beautiful, simple, and
easy to understand for any mechanic who took junior high electric shop.
Example: to check injectors, just bypass fuel pump safety relay, pull out
injectors and insert into a rack of test tubes, take off aircleaner and
pull up on air flow valve with a pair of pliers. Check fuel spray pattern
for quality and uniform flow. Other tests were just as simple: pressure,
control pressure regulator, etc. Now we need to deal with EFI.

EFI, unlike mechanical and electro-mechanical systems are so
counter-intuitive that they are self diagnosing. That is, within limits.
If the anomaly goes beyond the self diagnostic capability, you are in deep
trouble. Know any mechanics who have an oscilloscope to check injector duty
cycle simultaneously on all injectors? How about the capability to vary
the duty cycle for an in-shop test, with the injectors removed from their
ports and observed in test tubes for quality of spray and uniformity of
flow? Does you mechanic know how to test an absolute manifold pressure
transducer? Does he even know what one looks like? There are a hundred
wires running here and there with their associated connections. Did you
know none of those connections are gold plated? At one cent per
connection, gold plating would eliminate 99.9% of "intermittants"!
Instead, D-C specifies "grease" be used to shield connections from battery
acid spray. Yes, D-C has been known to route computer harnesses in contact
with naked lead-acid storage batteries.

Textbooks have been written for mechanics on the subject of EFI, yet none
knows any more rigorously about them as a series of "black boxes". All a
mechanic can hope to do is to use the on-board diagnostic or, in the event
there is no fault indicator, to isolate the faulty "black box" and
substitute a new one for the suspicious one. Hardly scientific diagnosis.
Reminds you of the "tube jocky" t.v. repairmen of the old days, doesn't it?

My point is, mechanical systems, which are far better from the servicing
standpoint, would be prefered by consumers. Electronic systems are
prefered by manufacturers because they don't have to "tune" them.
Consumers have to be aware of the fact that they, not manufacturers, are in
charge. By selecting products they buy, they tell manufacturers what to
build, not vice-versa.

I want to see electro-mechanical systems with full disclosure. That means
schematics for every component, every relay, every "black box".
Electro-mechanical is the most advanced technology we should have to put up
with in what is a mature, non-sophisticated product with limited function:
the automobile. Having full knowledge of its systems and components make
for efficient diagnosis and repair. This, the consumer is entitled to.

 

I have had no love for setting up the dual point distributor in one of my early
70's muscle cars.

Some of the electronics in todays cars are overly complicated, built with cost
rather than reliability in mind.

I hope we never go back to point ignitions or the Chrysler "Lean Burn" system.

Make todays electronics more reliable, design wiring harnesses so they won't
chafe and wear thru insulation against moving parts under the hood, make it
robust enough to not be affected by RFI and magnetic interfearance from other
gear and that would make me happy.

My father and grandfathers taught me the art of shade tree mechanics, honed
some more by my neighbors kids with engine swaps and bolt on performance parts.

I learned computers as a career. They stopped teaching us what was inside the
black box in the early 80's.

Steve

 

This is the most accurate and to the point analysis of the problem with auto
repair today. Changes are coming too fast for technicians to keep up with.

Retired Dodge tech/service manager

 

Well said except for one thing, cost of R&D plus cost of maintaining parts
and service knowledge base is beyond even normal expectations, therefore, a
"full-disclosure" vehicle will cost abnormally more than an equivalent mass
produced black box vehicle.

Simple laws of economics will prove the easier path.