Mechanical vs Electronic - Analog vs Digital

In article >,
says...
> Last year, the questions centered around timing belts and head gaskets.
> Mechanical items.
>

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



"Nomen Nescio" > wrote in message
...
> 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.
>

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.


"Nomen Nescio" > wrote in message
...
> 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.
>