Ign Advance on MR-2

[Bruce]

From: "Rich M" <rsrich at cwcom.net>
Subject: RE: Ign Advance on MR-2

> > From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
> > Behalf Of Les Newell
> > Sent: 12 August 2001 11:28
> > To: diy_efi at diy-efi.org
> > Subject: Re: Ign Advance on MR-2

> >The only way to make sense of these messy signals is to detect
> > the zero crossings as they will always be at the leading and
> > trailing edges
> > of the tooth.
>
> All reluctor systems will indeed detect the zero crossing of the voltage
> signal

Bzzzt, not all.  Gm uses a strategy that is slightly off from that so if the
ecm dies, there is some self induced advance in the system.
Bruce


- but just as a point of fact, the zero crossing of voltage output
> will always be in the centre of the tooth, which corresponds to zero rate
of
> change of flux in the reluctor coil while the target is right in front of
> the sensor.
> The voltage output is generated in response to a rate of change of flux in
> the reluctor coil.
> The voltage will swing one way as the target approaches (as the flux
starts
> changing), it will reach a peak at the edge of the tooth and start
reducing,
> reaching zero as the target covers the sensor. The opposite polarity
voltage
> occurs in the same way as the target leaves proximity to the sensor. Once
> the target leaves the face of the sensor, the voltage again returns to
zero
> as there is no rate of change of flux in the reluctor coil.
>
> Cheers
> Rich


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