[Efi332] newbie (also Autronic EFI and Bosch ignition modules)

[BowTieVette at aol.com]

Hi Erik,
 
I think the _only_ way to kill off coils is by overheating and/or  
overdriving them. I don't know exactly how automatic dwell systems work,  but I'd guess 
that they probably rely on limiting current at a certain  value or on sensing 
di/dt. They must have some short term learning or  memory feature to apply to 
the next spark event.
 
Regardless of the mechanism, if it isn't working or is tailored  for a higher 
impedance coil with longer charge cycles, that's not going to help  coil 
life. You can check by scoping the coil current draw. Typical dwell  durations are 
around 2-4 ms.
 
I imagine the cylinder head heat isn't helping much either. Do  you mean they 
are mounted to the head or the valve covers? Hopefully if its  the head, its 
on the intake side and not the exhaust side!  Are there any  insulators? Are 
the coils finned?
 
HTH
 
 
In a message dated 10/22/2006 12:16:19 A.M. Eastern Standard Time,  
ozone.breath at gmail.com writes:

Howdy all,
I'm an EE with several car projects; right now I'm trying to sort out a  
problem 
with my '65 Lotus Elan, which uses an Autronic ECU and a distributorless  
wasted 
spark ignition system.  The previous owner built both the  EFI system and the 
ignition system.  
 
The ignition system uses Bosch ignition drivers and Mitsubishi  coils.  I 
have been 
having problems with the car eating coils.  I wonder if they are  getting too 
hot.  The 
coils are mounted right to the head (they probably get pretty hot just  from 
this) but 
also I wonder if the ignition modules are working correctly.
 
I haven't gotten the ignition modules out yet to check the part  numbers, but 
I was 
told by the PO that they are the type that controls the dwell.   Apparently, 
the 
Autronic only sets the advance; the ignition drivers somehow (anyone know  how
they do this?) figure out ahead of time when to start charging the  coil, to 
charge to 
full current before the ECU triggers the  spark.



 
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