Ign Advance on MR-2

[Chris Conlon]

At 12:42 AM 8/11/01 -0600, Diehl, Jeffrey wrote:

>other with 1.  The single-toothed wheel is probably used to run the tach and
>is slightly offset from the cooresponding tooth on the 4-tooth wheel.

The tach should be run via a signal from the igniter. On an '87 it
probably just takes a signal from the low voltage side of the coil.

>There are no vacuum lines, so it is not doing vacuum advance.  The only
>moving part is the shaft on which the two wheels move.
>
>So, my question is: How does this mechanism manage to advance the spark?

That ECU uses an AFM. It doesn't measure MAP directly, but can figure
out load, based on RPM and the AFM signal. It then uses the load value
to adjust the spark timing. The ECU controls all aspects of spark
timing... except dwell, which is probably controlled by the igniter.

Actually that ECU is old enough that the Ne signal from the dizzy
(the one with more teeth) may go to the igniter, which then feeds a
copy of the signal to the ECU. (Operation is pretty similar to the
other setup, though, from the ECU's point of view.) Just a quirk to
watch out for when you're tracing down wires.

   Chris C.

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