[Diy_efi] RE: Using Flywheel as RPM/TDC Sensor?

[Joe Lopilato]

Hi:
I may be way off base, but these are my thoughts on this issue. If all you
want is TDC of #1 cylinder, it does not matter which tooth you pick. It
becomes a question of aligning a sensor with a tooth after establishing TDC.
A problem that you may run into with the Hall sensor is that any effects
from stray magnetic fields could cause the signal to be a degree or so off
TDC. A feedback loop that involves other sensors permits the pcm to
compensate for +/- perturbations in the data stream.
This is just an idea, but you might want to look at a light beam/sensor
which has a narrower field-of-view and might be more accurate.

Joe
-----Original Message-----
From: diy_efi-bounces at diy-efi.org [mailto:diy_efi-bounces at diy-efi.org] On
Behalf Of Steve Ravet
Sent: Thursday, December 23, 2004 4:26 PM
To: A list for Do-It-Yourself EFI
Subject: RE: [Diy_efi] RE: Using Flywheel as RPM/TDC Sensor?

________________________________

	From: diy_efi-bounces at diy-efi.org
[mailto:diy_efi-bounces at diy-efi.org] On Behalf Of Milanoguy
	Sent: Thursday, December 23, 2004 12:05 AM
	To: diy_efi at diy-efi.org
	Subject: [Diy_efi] RE: Using Flywheel as RPM/TDC Sensor?
	
	

	Hi
	Has anybody tried to use an  existing flywheel as a crank sensor for
an EFI system? I was thinking of using the ring gear teeth and a hall effect
sensor as the rpm sensor and a magnet screwed to the flywheel as the number
one cylinder TDC indicator.
	Would it be possible to take these two signals, run them thru some
kind of microprocessor and signal conditioner and generate a combined signal
that would be acceptable to a EFI CPU that is expecting either a Bosch 60-2
signal or the Ford 36-1 signal?
	The flywheel I intend to use has 131 teeth on the ring gear, 360
divided by 131 does not generate an even number like the Bosch
60(360degrees/60 teeth= 6 degrees per tooth) or the Ford (360 degrees/36
teeth= 10 degrees per tooth) instead the number is 2.74809 (rounded to the
5th place)  (360 degrees/131 teeth= 2.74809 degrees per tooth).
	So the signal must  first be converted into a more reasonable number
and then the flying magnet signal must be merged into the signal to look
like a missing teeth signal.
	Is this feasible? Or a dumb idea?


------------------------------------------------------------

Feasable, certainly, but is it more or less work than mounting the
appropriate wheel?  There was a batch or 2 of wheels made for the efi332
list if you're looking for a source for wheels.

--steve


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