DIY-WB Output Voltage Scaling

[Bob Wooten]

Thanks Phil, I thought it had some merit & as it is available to me, it sure
cant hurt anything, (well, nothing other than an old stroker motor).

BW

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of Phil Hunter
Sent: Sunday, August 26, 2001 2:37 PM
To: diy_efi at diy-efi.org
Subject: Re: DIY-WB Output Voltage Scaling


Peter wrote:
[snip]
> Best application I ever hear of for a Basic Stamp
> was turning LEDs on and off.
>
> Someone tell me otherwise.

Oh...all right...I'll take the bait...

There are several versions of the Basic Stamp and
several clones ( http://www.parallaxinc.com ,
http://www.micromint.com ), there are compilers
to home-brew your own ( http://www.melabs.com ),
Nuts & Volts magazine has been running a column
for years ( http://www.nutsvolts.com ), even doing
such sophisticated apps as voice recognition and
response. Not likely this much development would
have happened just for flashing LEDs.

Here you'll find a List of Stamp Applications
( http://www.hth.com/losa/ ) including using them for
driving auxillery fuel injectors, I don't think I'll
do that, but it gave me the idea to make a fuel
injector tester until I ran across the article here
(
http://www.diy-efi.org/diy_efi/projects/inj_flow/inj_flow.html
)
that I feel is more what I want.

I recently bought a Basic Stamp IISX, which is
quite fast vs. the original, I learned the quick
steps to program it by setting up a MAF simulator
using the Stamp as a simple square wave oscillator.

Detonation is a big bugaboo for the Turbo Buick
crowd, with a myriad of causes from the obvious
like dirty injectors, octane, and faulty ignition
parts to such off the wall things as cracked headers
and MAF ducting collapsing on the inside but not
outside. Trying to find the cause is generally
trial-n-error swapping of known good parts. Scantools
that I know of can tell how much detonation, but
not which cylinder or cylinders are having problems,
this info could help you focus your efforts. I've
been looking at ways to do this, since the cam,
crank & knock signals are all digital by the time
they get to the ECM ( '7148 ), a Basic Stamp 2 could
easily do the job, maybe even a BS1. Output COULD
be LED's, but I'd use RS-232. I've since found a
lower cost, more generalized solution that I'm
pursuing, so this project is on hold for now.

As for using a Stamp to process the output of the
WB sensor circuit, for monitoring I'd say go for it,
but if you're going to be using it in the control
loop of the ECM such as adapting the WB sensor to the
ECM's NB input, I'd be VERY cautious about the time
latency introduced by processing, lest you de-stablize
the system. If I were doing this, I'd figure out
some way to measure the time, and probably not let
it be longer than (guessing here) 1/4 revolution
at maximum RPM, and I'd start by processing the
NB sensor straight thru, byte in, byte out, with
some way to bypass the circuit for A - B comparisons
before making the changes and substituting the
WB sensor circuit.

regards,
phil

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