Perry Mick wrote:

Tracy Crook wrote:

Perry Mick wrote:

I think Tracy says in his book that Mazda uses different timing
between leading and trailing plugs ( I may be wrong about this,
haven't looked at the book for awhile) for emissions control
reasons.

However, when I look at the output of the Mazda ECU with an
oscilloscope, I see the leading and trailing pulses exactly in
sinc, at least at low rpm (<=2000).

The leading & trailing sparks are 15 degrees apart on the 86 & later 13B.
There are even two separate timing marks on the E-shaft pulley to check for
this.   I changed to same timing on both on my system as did Everett Hatch
on the Powersport engines.  Are you sure you had the sync setup right on the
scope Perry?

You're right, I even remember checking that with the timing
light awhile back. On page 5-34 of the Mazda '86 manual, leading
is 5 degrees ATDC, Trailing is 20 degrees ATDC.  I was looking
at the 5V pulses coming out of the ECU, going to the igniters.  
Triggering the scope on one and looking at the other on the
second channel, using chop mode to eliminate triggering skew   
problems.  There is an electronics module in the trailing
igniter/coils that takes in two signals, IGt-T, the trigger
signal, and IGs-T, a switch signal that routes the trigger   
signal to alternate igniters for the two rotors.  Then there is
the 12v feedback signal to the ECU, IGf-T, that tells the ECU
rpm.

The trigger signal for the Leading coil, IGt-L, fires the
igniter to the single coil to both leading plugs.

IGt-L and IGt-T were the signals I was looking at.  I'll take
another look, must be some kind of triggering problem.

Perry Mick

 
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