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

Paul Helmuth PaulHelmuth at SprintMail.com
Thu Dec 23 06:20:33 GMT 2004


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If the ECU that you are providing engine position information expects a =
60 minus 2 input then you need to feed it 58 pulse (60 with two =
consecutive missing at TDC). The software inside the ECU will be =
calculating (or trying to) the engine position based on the number of =
pulses and the expected missing pulses. So if your flywheel doesn't =
match the "expected" pattern then it won't work.

On the other hand, if the ECU only expects a pulse at TDC then your =
magnet idea becomes more feasible (but I don't think that it is likely =
that any ECU only wants a single pulse at TDC for engine position info).
  ----- Original Message -----=20
  From: Milanoguy=20
  To: diy_efi at diy-efi.org=20
  Sent: Thursday, December 23, 2004 12:05 AM
  Subject: [Diy_efi] RE: Using Flywheel as RPM/TDC Sensor?


  Hi

  =20

  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.

  =20

  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?

  =20

  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=3D 6 degrees per tooth) or the Ford (360 =
degrees/36 teeth=3D 10 degrees per tooth) instead the number is 2.74809 =
(rounded to the 5th place)  (360 degrees/131 teeth=3D 2.74809 degrees =
per tooth).

  =20

  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.

  =20

  Is this feasible? Or a dumb idea?



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<META http-equiv=3DContent-Type content=3D"text/html; =
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<BODY bgColor=3D#ffffff>
<DIV><FONT face=3DArial size=3D2>If the ECU that you are providing =
engine position=20
information expects a 60 minus 2 input then you need to feed it 58 pulse =
(60=20
with two consecutive missing at TDC). The software inside the ECU will =
be=20
calculating (or trying to) the engine position based on the number of =
pulses and=20
the expected missing pulses. So if your flywheel doesn't match the =
"expected"=20
pattern then it won't work.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT face=3DArial size=3D2>On the other hand, if the ECU only =
expects a pulse=20
at TDC then your magnet idea becomes more feasible (but I don't think =
that it is=20
likely that any ECU only wants a single pulse at TDC for engine position =

info).</FONT></DIV>
<BLOCKQUOTE=20
style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; =
BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV=20
  style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: =
black"><B>From:</B>=20
  <A title=3Ddigestingtheinternet at yahoo.com=20
  href=3D"mailto:digestingtheinternet at yahoo.com">Milanoguy</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A =
title=3Ddiy_efi at diy-efi.org=20
  href=3D"mailto:diy_efi at diy-efi.org">diy_efi at diy-efi.org</A> </DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Thursday, December 23, =
2004 12:05=20
  AM</DIV>
  <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> [Diy_efi] RE: Using =
Flywheel as=20
  RPM/TDC Sensor?</DIV>
  <DIV><BR></DIV>
  <DIV>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt"><FONT face=3D"Times =
New Roman"=20
  size=3D3>Hi</FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt"><FONT =
size=3D3><FONT=20
  face=3D"Times New Roman">&nbsp;<o:p></o:p></FONT></FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  face=3D"Times New Roman" size=3D3>Has anybody tried to use an<SPAN=20
  style=3D"mso-spacerun: yes">&nbsp; </SPAN>existing flywheel as a crank =
sensor=20
  for an EFI system? I was thinking of using the ring gear teeth and a =
hall=20
  effect sensor as the rpm sensor and a magnet screwed to the flywheel =
as the=20
  number one cylinder TDC indicator.</FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  size=3D3><FONT face=3D"Times New =
Roman">&nbsp;<o:p></o:p></FONT></FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  face=3D"Times New Roman" size=3D3>Would it be possible to take these =
two signals,=20
  run them thru some kind of microprocessor and signal conditioner and =
generate=20
  a<SPAN style=3D"mso-spacerun: yes">&nbsp; </SPAN>combined signal that =
would be=20
  acceptable to a EFI CPU that is expecting either a Bosch 60-2 signal =
or the=20
  Ford 36-1 signal?</FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  size=3D3><FONT face=3D"Times New =
Roman">&nbsp;<o:p></o:p></FONT></FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  face=3D"Times New Roman" size=3D3>The flywheel I intend to use has 131 =
teeth on=20
  the ring gear, 360 divided by 131 does not generate an even number =
like the=20
  Bosch 60(360degrees/60 teeth=3D 6 degrees per tooth) or the Ford (360 =
degrees/36=20
  teeth=3D 10 degrees per tooth) instead the number is 2.74809 (rounded =
to the=20
  5<SUP>th</SUP> place)<SPAN style=3D"mso-spacerun: yes">&nbsp; =
</SPAN>(360=20
  degrees/131 teeth=3D 2.74809 degrees per tooth).</FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  size=3D3><FONT face=3D"Times New =
Roman">&nbsp;<o:p></o:p></FONT></FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  face=3D"Times New Roman" size=3D3>So the signal must<SPAN=20
  style=3D"mso-spacerun: yes">&nbsp; </SPAN>first be converted into a =
more=20
  reasonable number and then the flying magnet signal must be merged =
into the=20
  signal to look like a missing teeth signal.</FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  size=3D3><FONT face=3D"Times New =
Roman">&nbsp;<o:p></o:p></FONT></FONT></P>
  <P class=3DMsoNormal style=3D"MARGIN: 0in 0in 0pt; TEXT-ALIGN: =
justify"><FONT=20
  face=3D"Times New Roman" size=3D3>Is this feasible? Or a dumb=20
  idea?</FONT></P></DIV>
  <P>
  <HR SIZE=3D1>
  Do you Yahoo!?<BR>The <A href=3D"http://my.yahoo.com">all-new My =
Yahoo!</A> =96=20
  What will yours do?
  <P>
  <HR>

  <P></P>_______________________________________________<BR>diy_efi =
mailing=20
  =
list<BR>diy_efi at diy-efi.org<BR>http://lists.diy-efi.org/mailman/listinfo/=
diy_efi<BR></BLOCKQUOTE></BODY></HTML>

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