Crank Trigger Signal (was monitoring RPM)

[Frederic Breitwieser]

>trigger wheels over a single tooth wheel.  What is the advantage
>of receiving 60 pulses per revolution over a single pulse?

The major advantage of multi-teeth wheels is that by having more pulses per
revolution, you can determine crank position within 360/number of teeth.
60 Pulses gives you crank position within 6 degrees of rotation...

>Does this simplify the hardware or software?

Gives more information to the ECM, if you want it :)

>Can the engine change its RPM significantly within a single
>revolution?

Yes.  Worse case scenario - if the engine stalls (0 RPM), as you crank it,
you can determine the crank position and know which fuel injector to fire
off so the engine starts.  Firing off injector six when cyl 1 is at TDC
won't start the engine.

>bright daylight for static checks and adjustment.  It's a
>similar method that is used for barcode readers found in
>the grocery store.  Certainly an eye catcher for the curious

Yes, however if you have ever bought a "dirty" soda can, you might have
found a frustrated checker trying to read the bar code - therefore dirt and
gunk, if accumulated enough, can interfere with the laser diode's output,
especially if its visible light.  Blockage within line of sight is still
blockage.  I've exerimented a lot with laser diodes, in making laser-based
walkie talkies. I had one mounted on my window sill (this was about 10
years ago) to talk to a friend, who lived next door.  Dirt, grime, and even
blue jays (if they sat on the same window sill) affected performance
noticibly.


Frederic Breitwieser
Bridgeport, CT 06606

Homebrew Automotive Website:
http://www.xephic.dynip.com/