DIY_EFI Digest V3 #445

[Bruce Plecan]

-----Original Message-----
From: Mike Pitts <mpitts at netspeak.com>
To: 'diy_efi at efi332.eng.ohio-state.edu' <diy_efi at efi332.eng.ohio-state.edu>
Date: Tuesday, September 29, 1998 4:26 PM
Subject: RE: DIY_EFI Digest V3 #445


>Yeah, it's the 8625.  I thought it was interesting that 
>some ECM's would use 4000 and others would use 2000. 
>I forgot to mention the VSS buffer between the VSS and 
>the PCM though, I wonder what that does.

Signal converter.  The trucks have a sensor that is more like a 
hall effect switch, if I understand it, correctly.  Was/is called a 
DRAC.  I "think" the trucks thew out this have stayed 2000ppm.
Cordin to past info. your tranny probably has a 40 tooth reluctor
on the output shaft.  The DRAC takes that signal, and depending
on the tire diameter/gearing figures out the divide by ratio.
then sends that to the ecm/dash.
Cheers
Bruce
>
>
>-----Original Message-----
>
>Was talking about a 730 ecm.  I consider the 2000 as close enough, is all
>I think it can be worked out into decimal points.
>
>I'm talking about two issues here, the 2000+4000 ppm, and how to inferface
>them, for ecm transplants.
>
>This is on your 8625?..  The 2000ppm.
>
>
>>>>Feeding a 2000 pulse into the computer would give the
>>>>computer a half speed input.
>>
>>Interesting.  My service manual states that my VSS sends
>>2002 pulses per mile.  This is a '93 CPI engine with the
>>electronic trans.
>>
>>-Mike
>>
>