[Diy_efi] Timing Calculations

[Steve Ravet]

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of amdcpu
> Sent: Wednesday, June 15, 2005 6:08 PM
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] Timing Calculations
> 
> Hi.
> With 60 tooth-wheel you can count teeth. Every tooth is 6deg. 
> If needed
> advance would be 26deg BTDC
> (26deg / 6deg/tooth) = 4tooth - 2deg BTDC.
> When 5th tooth BTDC has triggered, we know that we must wait 
> 6deg/tooth-2deg
> = 4deg.

How often does your algorithm calculate spark timing?  If it does the
calculation separately for each cylinder then this 60 tooth wheel helps.
If it does it once per revolution and uses that value for all sparks
during the revolution then it doesn't matter how many teeth you have,
the rpm may change between between calculations.

I don't think OEM hardware does rpm prediction, or at least didn't in
the TPI/TBI days.  But I may be wrong.

--steve