Cam position sensing w/o a cam sensor

[Shannen Durphey]

Using crank position, opposite cylinders can initially be fired together.  The
voltage required in the cylinder w/ compression is higher.  Lesson left over
from waste spark, and similar methods might be applicable to that system.  If
you're watching cylinder #1 for this higher voltage, you can tell whether the
coil is firing during a compression or exhaust stroke.

Shannen


Jim Blackwood wrote:
> 
> But isn't that a little circular? Assuming the purpose of sensing #1 is
> to fire #1 wouldn't sensing the spark to start the process just cause
> more trouble?
> 
> Jim
> 
> -----Original Message-----
> From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org] On
> Behalf Of Jason Haines
> Sent: Monday, November 26, 2001 9:42 PM
> To: diy_efi at diy-efi.org
> Subject: Re: Cam position sensing w/o a cam sensor
> 
> Some of the new ignition systems determine the cam position through
> ionization energy or similar voltage/spark plug related methods. The new
> L850 "world" 4 cylinder from GM (that is in the Cavalier, Sunfire, Vue
> (Saturn), Opel (can't remember the model), etc. ) uses this method. No
> cam sensor - uses the individual cylinder ignition system to determine
> cam position. I wonder how quickly it figures it out. I am not sure what
> manufacturer makes the PCM/ECM.
> 
> Jason
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