Forwarded: Re: Flywheel/Encoder patterns

[RABBITT_Andrew at mv8.orbeng.com.au]

Sorry Mazda, SAAB have beaten you to this idea.  Take a look at SAE 
890044, "SAAB Direct Ignition System and its Cold Start Performance"

Andrew.

From: (Mazda Ebrahimi) kleenair at ix.netcom.com:smtp
Date: ## 12/21/96 05:49 ##
Based on previous discussions, I think we determined that the most 
accurate spark system would be driven by the crankshaft pick-up sensor, 
with a TDC#1 reference from the camshaft sensor.  In the interest of 
reducing sensor count, I'm interested in determining TDC#1 at top of the 
compression stroke without monitoring Camshaft position.  The method I 
have in mind would be based on ionization current in the ignition 
system.  I think there are several ignition drivers available now that 
can feedback this info to the processor.  Is this right?  If so, does 
anyone know any part numbers?

I think by going to a waste spark system and gang fire injector firing 
during the first few engine rotations, we can compare the ionization 
currents between the two sparks for each cycle of each cylinder and 
determine which one represents the top of the compression stroke.  Based 
on this determination, we can then go to sequential injector firing, and 
eliminate the waste spark to prolong ignition system life.  Any comments 
on difficulties I might run into??

Best Regards, Mazda