Cam position sensing w/o a cam sensor

[Craig Dotson]

> IIRC, it is a two tooth wheel (180 degree oppossed teeth) on a cam with a
> sensor mounted in the valve cover.  It is very similar to the crank sensor
> setup except for it's location difference the the difference in the number
> of teeth.  I don't see why they used two teeth 180 degrees opposed because
> you then lose the ability to sync your signal according to a particular
> valve event (say combustion vs intake on #1).

Actually, I just was messing with the sensor last night.  It's a 3-tooth cam
sensor.  Two of them are 180 degrees apart, and the third one is
approximately 30 degrees (haven't measured it) rotated from one of the
teeth.  The cam trigger is mounted on the exhaust cam, and the sensor is
mounted in the head.  The trigger wheel has a non-symmetrical bolt pattern,
so it's essentially idiot-proof at the factory, but removes the possibility
of re-aligning it.

On your F4i, you can see through the access hole in the sidecover that the
crank trigger is a 12 tooth wheel.  Nine of the 12 are straight teeth, while
three have "shoulders" of sorts.  The shouldered crank teeth align with the
crank sensor at approximately the same time as the cam teeth align with the
cam sensor (at least to my uncalibrated eye).

Craig Dotson
crdotson at vt.edu
2002 VT FormulaSAE

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