[Diy_efi] Interesting AFR sensing idea

[Adam Wade]

--- Perry Harrington <pedward at apsoft.com> wrote:

> Would it be possible to detect precise AFR readings
> based on the firing voltage of a cylinder's spark?

> If the voltage is higher the cylinder is lean, lower
> and it's rich.

A very good idea, and one that makes a great
diagnostic tool under certain circumstances, but a bad
idea (IMHO) for use in place of an exhaust sensor.

Why?  Because you're detecting not OVERALL mixture,
but mixture AT the gap, and nowhere else.  You might
have fairly good luck by averaging over time, or as I
mentioned, it makes a great diagnostic tool for
cylinder head and intake port design, as well as for
placing injectors in the plenum, by checking spark gap
mixture constancy, and by comparing measured mixture
at the gap vs. in the tailpipe.

=====
| 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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