[Diy_efi] Newbie here

[Steve Ravet]

Hi Dave, welcome aboard. 

> -----Original Message-----
> From: diy_efi-bounces at diy-efi.org 
> [mailto:diy_efi-bounces at diy-efi.org] On Behalf Of 
> junkie4 at earthlink.net
> Sent: Wednesday, November 30, 2005 5:12 PM
> To: diy_efi at diy-efi.org
> Subject: [Diy_efi] Newbie here
> 
> Hi all, 
> 
> First time poster here.  I'm trying to put TBI on a Toyota 
> inline 6 engine, and I have acquired some parts already I 
> have a 1227747 the original harness from a Chevy k1500, a 
> Throttle body, and tons of reading material.  I just noticed 
> that the TPS  on the Throttle body I have is of the older 
> type plug(looks like the MAP sensor plug), and the harness 
> has the newer roundish plug.  Is my best course of action 
> here to buy a newer sensor, or to find a pigtail and solder 
> it onto the harness?   I'd also like to ask how to understand 
> the bin listings you have on the FTP site.  I don't quite 
> understand what listings are for what engines, and what options.   

Keep reading on gmecm and other pages and things will start to connect
in your head.

The bins are listed by broadcast code.  There's a snapon book that some
list members have that decode the broadcast code into applications, if
there is a particular one you need then ask and someone can probably
answer it.  The letter code can't be decoded into anything, it has to be
looked up.  You always want to start with a bin that matches your
application as closely as possible, at least for #cylinders and
transmission type.  A 4.3L v6 bin is probably best for you.

> 
> If anyone has any information on how to interface the 
> distributor off my I-6 engine to the ECM, I'd love to read 
> that as well.  That's the area I am weakest in my 
> understanding.  I don't see how the GM distributors actually 
> change the position of the rotor to change the timing.  I 
> suppose they could NOT change the position and just let the 
> spark jump, but that seems wasteful.  I don't understand what 
> the 4 wires leading from the distributor  actually tell the 
> ECM. (When to fire and when to inject is obvious, but that 
> would seem only like 2 wires.)   Trying to understand what 
> all is going on.  

The rotor on EFI engines is fixed to the shaft.  Timing is controlled by
the computer and the spark jumps a varying sized gap between rotor and
terminal, depending on the timing at that instant.  As far as the
electrical interface, take a look at the ftp site for these documents:

ftp://ftp.diy-efi.org/uploads/7PIN_SCH.GIF

ftp://ftp.diy-efi.org/uploads/DIS+inj_timing1.gif

The first is the pinout of the ignition module.  Module pins E,R,B are
the important ones (G is ground, important but self explanatory).  R is
reference.  This is the signal from the pickup coil, cleaned up and sent
to the ECM.  It provides RPM and position information.  E is the EST pin
from the ECM to the module.  The ECM calculates timing, and uses E to
tell the module when to fire the spark.  B is bypass.  During cranking,
and if the computer is out to lunch, bypass will be asserted and the
module will supply a spark all by itself, without looking at the R pin.
this timing is basically static, with a constant advance from 0-2000
rpm, and a different constant advance used from 2000 up.

Looking at the second diagram, the signal "reference pulse to ECM" is
the R pin.  A little further down you see box "IGN ADV" that represents
a window of time where a spark can occur.  Sometime during that window
the ECM will assert E in response to R, and the module will fire the
spark.  This diagram is actually for DIS, so it shows a crank sensor,
but the coil in the distributor serves the same function in the
distributor wiring.  This diagram also shows an injector pulse but that
is a different set of wires, and has nothing to do with the distributor
wires.

Finally, since you're working with GM parts here, you'd be best off to
post on gmecm instead of DIY.

hope that helps some,

--steve