[Diy_efi] Newbie with a simplified Motronic project

[Shannen Durphey]

Adam Wade wrote:
> 
> --- Eric D Byrd <klox at juno.com> wrote:
> 
> > Every electrical component ever manufactured
> > eventually -- eventually -- experiences changes in
> > its operating characteristics due to age, especially
> > if heat is involved, and more especially if extreme
> > variation of temperature is involved.
> 
> True, except this isn't a sensor in the traditional
> sense.  It's simply a resistive wire, and if that
> changes its resistance vs. temperature profile, then
> we'll have to rewrite physics!  :D

The resistive element does change.  Thermal cycling changes the metal.

Why do electric oven elements burn out?
Why do toasters burn out?
Why do light bulbs burn out?
Why do automotive (or other) fuses mysteriously fail when there is no short
circuit present?

I would be disbelieving of any argument that does not provide for the
resistance of the element to change as the element approaches failure.

And there is the very real issue of contaminant accumulation on the
hotwire.  If it were a non-issue, there would be no heat cycle applied to
the sensor wire.  There would also not be OEM issued service bulletins
discussing
checking of the sensor wire.


> Therein lies the learning curve.  ;)  Many of these
> manufacturers (Bosch especially) have been doing this
> for eons, just about, and they don't tend to get
> surprised too often.  ;)

But they do!  Witness Delco's poorly designed MAF sensor of the 80's, or
the failure rate of Bosch MAF sensors in early F and Y car GM vehicles. 
It's the surprises that keep dealerships' technicians performing warranty
repairs.

Shannen
> 
> > It's a mistake to assume a device will never
> > experience variations in its response, from
> > physical effects we haven't accounted for.
> 
> Again, it would be a pretty spectacular upheaval of
> the laws of physics if a stable metal changed its
> resistive characteristics over time, AFAIK.  ;)
> 
> > It's worthwhile to educate, and be educated.  But I
> > have better things to do with my time, than trade
> > verbal abuse.
> 
> Definitely avoid doing so.  I do myself.
> 
> Certainly, if you perceived anything I said as "verbal
> abuse", I regret any misunderstanding on your part.  :D
> 
> =====
> | Adam Wade                       1990 Kwak Zephyr 550 (Daphne) |
> |   http://y42.photos.yahoo.com/bc/espresso_doppio/lst?.dir=/   |
> | "It was like an emergency ward after a great catastrophe; it  |
> |   didn't matter what race or class the victims belonged to.   |
> |  They were all given the same miracle drug, which was coffee. |
> |   The catastrophe in this case, of course, was that the sun   |
> |     had come up again."                    -Kurt Vonnegut     |
> 
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