FW: RE: Multispark

[john carroll]

I believe that the real advantage of the waste 
spark system is that it relieves a DIS system of 
determining and tracking which of two cylinders is 
at TDC firing and which is at TDC exhaust.  A 
sensor to watch the cam is unnecessy (cheaper, more 
reliable).  There are half as many coils as spark 
plugs (cheaper, more reliable). The system is 
probably lighter ( " " ).

These systems pulse each injector each revolution, 
two at a time.  One hit comes on the intake stroke, 
the other on the back of the valve in the power 
stroke.  Each pulse can last longer with out the 
problems of overlapping injection timing.  This 
greater on-time allows better resolution of the 
fuel flow.  The software and hardware overhead are 
both reduced.

If plating material from one plug electrode or the 
other is a problem, one can switch the plug leads 
from one side of the coil to the other 
occasionally to even out the wear.




>I was under the impression that there were 
benefits to waste fire - else 
>why would anyone have used it at all? As for 
wasting a spark, I thought it 
>was firing the waste? I'm confoozed here! I have 
been told that it reduces 
>emissions - is this it's only saving grace?
>
>----------
>>From: 	Edward Hernandez 
(R)[SMTP:ehernan3 at ford.com]
>Sent: 	Monday, April 01, 1996 1:57 AM
>To: 	diy_efi at coulomb.eng.ohio-state.edu
>Subject: 	RE: Multispark stuff and other 
thoughts
>
>
>"Why fire two plugs? Waste fire! I'd love to take 
a shot at burning
>any unused fuel left in the chamber..."
>
>To what end? It will do you no good to burn charge 
on the exhaust stroke 
>because you won't get any work out of it. You 
certainly risk
>burning exhaust valves and other downstream 
components and if you
>are convinced that you have burnable charge left 
in the chamber
>during the exhaust stroke, you should take actions 
to prevent that
>condition, such as running excessively rich. The 
term wastefire was
>coined because you waste a spark in unburnable 
conditions.
>
>Ed Hernandez
>Ford Motor Company
>ehernan3 at ed8719.pto.ford.com
>
>
>
>