VSS importance

Jeffery Flanary jefff at mounet.com
Wed Sep 30 02:40:17 GMT 1998


Hello all, i am new to the list and am getting some very useful info.  I
have an 87 S10 Blazer with 8" of lift and 33x12.50's.  I installed a 305
TBI V8 which originally used a 16136965, but have since changed to a
1227747.  When i first started the swap, i wasn't sure if i'd need the VSS
that hooks up at the transfer case, or if i could use the sensor that is
built into my speedometer.  I purchased a Cyberdyne speed sensor and a
calibration box.  A friend of mine used this setup on his 86 S10 TPI with
the 730 computer.  After i realized that my speedo sensor worked, i gave
him the Cyberdyne stuff for spares.  Anyway, thanks for the good info

P.S.  When i switched to the 747 computer, i changed the prom only.  A
friend who sold his truck gave me a power chip he had for an 88 Chevy TBI
350 auto.  I am running this chip even though it is a 305.  The hypertech
guys said the only difference was the injector pulse width and recommended
i buy the 305 chip, but the truck runs great with the 350 chip.  Also, i
didn't change the calpak.  The computer was in an 88 Astro Van with a 4.3. 
I have heard that it only uses the calpak in limp in mode.  Is this true? 
Sorry to be so elementary on such a high tech list, but i am just getting
started. 

				Thanks, Jeff

----------
> From: Bruce Plecan <nacelp at bright.net>
> To: diy_efi at efi332.eng.ohio-state.edu
> Subject: Re: VSS importance
> Date: Monday, September 28, 1998 10:35 PM
> 
> 
> -----Original Message-----
> From: T Hergen <thergen at svn.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Monday, September 28, 1998 9:34 PM
> Subject: Re: VSS importance
> 
> These aren't the best of answers maybe some one can chime in, please..
> 
> 
> >The x2 or /2 is half the puzzle.  I'm don't know what the vss sensor
> >outputs or the ecm vss input expects.  Does anyone know what range of
> >voltages a vss sensor will produce? 
> 
> It's like a motor with a gear on the end, just a little A/C generator.
> As I recall they can light up a LED.  I think the words zero crossing
> was used.
> 
>  Does anyone know what the minimum AC
> >voltage swing is needed on the various vss inputs?
> 
> The 730 type of ecm at 4000ppm is A/C. and the 2000ppm is
> a pulsed DC.
> >
> >These same questions will come up if a phase locked loop is used.
> >
> >Bruce, in your 555 thru a cap to vss experiment, was the 555 powered by
> >12v or 5v?
> 
> Between my eyes, and lighting I'll have to look again in the am.
> There is a 78XX..
> Cheers
> Bruce
> >
> >Thanks,
> >Tom
> >
> >



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