Technical foul: distributor+garden hose

[spewey at comcast.net (Spewey)]

"Question:  90 323 2dr hatchback 1600 mileage: 125000.  I recently 
bought the car and it started and ran fine.  Then I washed out the 
engine compartment with a hose.  Now the car will not start.  No spark. 
  The distributor cap and wires are OK.  There is voltage at the 
ignition coil and igniter.  The engine diagnostic code says 2 flashes - 
my shop manual says this means "Distributor No signal" (sic).  What can 
I do?

Answer:    Replace the distributor."

http://www.2carpros.com/makes/mazda/323.htm

This is not me but this happened to me this weekend.  I agreed to "look 
at" a friend's mom's [grandma-type] car which had been dying at idle 
randomly.  323 is a good hothatch and the 1.6 in it is very Rabbit-like 
so I dig in.  Isn't it funny how often the throttle cable is all slack 
on cars?  I should advertise 30% more hp on select vehicles FREE!

So I did that kind of thing and checked tune-up stuff and test drove it 
and it ran well for a few short trips and didn't die and then POOF! 
Nothing.  No starty-start.  OBD-I now says blink,blink "Distributor Ne 
signal" error.  This apparently is Japanese for _N_umber of _E_ngine 
revolutions and comes from the distributor Hall sender.

Interestingly, the PCM/ECU/brain shuts down the injectors when it sees 
this.  Now spark plugs are not gas-wet in no-spark situations.
{Is Digifant that smart?  The later systems?  I am an A1 guy...}  The 
Check Engine (yup! still there!) light would come on if it ran but it 
didn't when I got it.  That means I broke it or it was a big 
coincidence.  The only thing I could have done to break it was rinse off 
some dust.  This engine had no grime and I was careful.

Now if you read this far and you hated me already from before, you can 
just go, "Hunh, I knew he was a jerk and idiot."  But if you like 
technical discussions you could answer me this:

*How does moisture screw up Hall effect (breaker-less) distributors?*

Does it short the gap between magnet and wheel thus frying internal 
circuitry?  Everything else is enclosed within the sender on most all 
cars.  I know many people recommend a plastic bag for garden hose 
operations but all engine stuff basically lives in a wet environment 
when it rains and I have hosed (funny, eh?) many engines with no ill 
effects just by not pelting sensitive areas directly.

Feel free to share stories, elaborate technical explanations, 
experiences, idiot confirmations, or the secret location of a '93 323 
that no one is watching too closely.