hall sensor simple questions

[nacelp]

> As I understand it, a hall sensor can detect a metal mass approaching the
> sensor i.e. a distributor cam rotating and a hall sensor sensing the
lobes.

Yes

> Crank shaft sensors can determine the position of the piston and therefore
> give the ECU a timing reference inorder to inject fuel at the right time.
> How many sensors do you need around the crank inorder to get a resolution
> that is useful?

On some GM applications, they use 7 notches in the crank and one sensor (6
cyl), there are other strategies, like for SEFI, where you need to know cam
posistion.

 Is this multiplied by each cylinder as well? or can the ECU
> calculate where one piston is compared to another's location?

??. No reason to, that I can think of unless maybe for odd fires.

> Crank shaft sensors seem hard to implement on an old engine with no stock
> electronics what so ever. I was thinking about using the distributor's cam
> with a hall sensor in order to get spark timing and as well as Fuel
> Injection timing and thereby doing away with crank sensors completely. Is
> this possible?

Sure, numerous configurations use just Distributor signals.

 are the hall sensors accurate enough to not only detect a
> lobe peak but the lobe's approach and exit?

As far as I knoe they are digitial, you want an analog then pickup-coil
reluctor is for proximity.
Grumpy


> Please help out a novice here...
> Thanks for your help
> Toby Atwater
> 1969 Austin Healey Sprite
> 1971 Toyota Land Cruiser
>
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